I, for the most part, enjoyed this unit. It is always good to be refreshed on out role in restoring a balance to the energy cycles
1. The assignments I was most proud of were the first compendium, the first lab activity and the second quiz, which was only the second one I got a perfect score on.
2. I certainly could have worked harder on the lab project for this unit. I also didn't review the second part of the unit as much as I did the first part, just because it was longer.
3. I think I should bet a low A or high B for the unit.
4. The next unit does not exist, but for my next class, whatever it is, I can certainly put a little time in it daily/nightly and not do a lot of work just two or three days a week.
Sunday, May 11, 2008
Species Interaction
scientific name: Streptococcus Durans
common name: cheddar bacteria
relationship: mutualistic/symbiotic/commensal
Humans and bacteria have apparently found the benefit of living together
as the bacteria have a good environment to live in inside humans
and humans use them to maintain health and immunity.
scientific name: Streptococcus Cremoris
common name: sour cream bacteria
relationship: mutualistic/symbiotic/commensal
Humans and bacteria have apparently found the benefit of living together
as the bacteria have a good environment to live in inside humans
and humans use them to maintain health and immunity.
scientific name: Lactobacillus
common name: dairy bacteria (yogurt)
relationship: mutualistic/symbiotic/commensal
Humans and bacteria have apparently found the benefit of living together
as the bacteria have a good environment to live in inside humans
and humans use them to maintain health and immunity.
scientific name:Coturnix cotumix japonica
common name: quail
relationship: mutualistic/predator, prey
Humans have come to enjoy the entertaining antics
of quail as well as their delicious and nourishing meat.
non-domesticated (mostly)
scientific name:Roseburia
common name: intestinal bacteria
relationship: mutualistic/symbiotic/commensal
Humans and bacteria have apparently found the benefit of living together
as the bacteria have a good environment to live in inside humans
and humans use them to maintain health and immunity.
scientific name: Canis Familiaris
common name: dog (rottweiler)
relationship: mutualistic
Domesticated animal
Scientific name: Streptococcus Boulardii
common name: bacteria in Kombucha tea
relationship: mutualistic/symbiotic/commensal
Humans and bacteria have apparently found the benefit of living together
as the bacteria have a good environment to live in inside humans
and humans use them to maintain health and immunity.
scientific name: Aphonopelma rusticumcommon name: Arizona tarantula
relationship: mutualistic
non-domesticated animal
scientific name:Pituophis
common name: bull snake, gopher snake
relationship: mutualistic (beneficial to us)
If humans have been smart enough to put them in their gardens to take
care of pests, they really have evolved!
scientific name:Felis
common name: house cat
relationship:mutualistic
Humans have benefited from the companionship
domesticated pets can give. Cats have benefited from the
cat food!
scientific name: taurus
common name: bovine
relationship: mutualistic/symbiotic/predator, prey
domesticated animal
Cows can benefit from the grazing lands we provide and close care...
until they end up on our plates.
scientific name: Gallus gallus domesticus
common name: legbar hen
relationship: mutualistic/ predator, prey
domesticated and delicious animal.
scientific name: Musca Domestica
common name: house fly
relationship: mutualistic, parasitic
Name suggests it is domesticated, but that refers to its adaptation
to living with, around humans
Humans have adapted by coming up with fly swatters,
sprays, and fly pater.
common name: house fly
relationship: mutualistic, parasitic
Name suggests it is domesticated, but that refers to its adaptation
to living with, around humans
Humans have adapted by coming up with fly swatters,
sprays, and fly pater.
Saturday, May 10, 2008
Overpopulation or Overconsumption?
It is certainly true that the impact of the population increase in the less developed countries will have a major impact on the environment and food demand. Is there much more that can be done other than attempting a population control in those countries? Of course there is. Consumption seems to be as much, if not more so, a contributing factor to food demand and environmental impact.
Those who live in the more developed countries consume almost 100 times the amount of energy needed to be sustained. What's more, most of this energy is from nonrenewable sources, such as fossil fuels. Water consumption is rampant, especially in agriculture and industry. But it is used by the everyday person in a more developed country for bathing, irrigation, cooking and flushing toilets than it is for drinking. People in more developed countries are irresponsible with food consumption as well. Not only do they generally consume more food than needed, they consume a lot more meat than needed. Meanwhile the lack of protein in the diets of many people in the less developed countries is alarming. The excess consumption of meat by people in the more developed countries, particularly the US, also uses a lot more grains than if the people had a vegetable-high diet.
Of course, our consumption certainly affects the people of less developed countries. Our demands for goods and services put a demand on them to work with whatever will get the job done quickest. This usually means environmentally detrimental practices that they perpetuate because of the competitive nature of people in more developed countries. This causes adverse effects to the land. Some of these ecosystems, such as the forests and marine ecosystems may never recover. This simply adds to the energy and food crisis.
The solution is obvious. If the more developed countries lead by example in areas of energy conservation and innovating renewable sources they will greatly reduce energy used worldwide. This would lead to a surplus usable by less developed countries. They will also push less developed countries to follow suit.
Those who live in the more developed countries consume almost 100 times the amount of energy needed to be sustained. What's more, most of this energy is from nonrenewable sources, such as fossil fuels. Water consumption is rampant, especially in agriculture and industry. But it is used by the everyday person in a more developed country for bathing, irrigation, cooking and flushing toilets than it is for drinking. People in more developed countries are irresponsible with food consumption as well. Not only do they generally consume more food than needed, they consume a lot more meat than needed. Meanwhile the lack of protein in the diets of many people in the less developed countries is alarming. The excess consumption of meat by people in the more developed countries, particularly the US, also uses a lot more grains than if the people had a vegetable-high diet.
Of course, our consumption certainly affects the people of less developed countries. Our demands for goods and services put a demand on them to work with whatever will get the job done quickest. This usually means environmentally detrimental practices that they perpetuate because of the competitive nature of people in more developed countries. This causes adverse effects to the land. Some of these ecosystems, such as the forests and marine ecosystems may never recover. This simply adds to the energy and food crisis.
The solution is obvious. If the more developed countries lead by example in areas of energy conservation and innovating renewable sources they will greatly reduce energy used worldwide. This would lead to a surplus usable by less developed countries. They will also push less developed countries to follow suit.
Human Population Demographics
1. The high fertility rate country was Botswana with a rate of 4.2 children
2. The low fertility rate country was Australia with a rate of 1.8 children.
3. If for every couple, there is an average of 4 children, as in Botswana, than the ratio of children to parents is 2:1. That means the ratio of children to grandparents is 4:1 and so on. This creates a pyramid effect when looking at populations.
4. In a country with a lower fertility rate, like Australia, the opposite is true. There is a slightly unbalanced number of children to parents, with 1.8 children to 2 parents. That means there are 4 grandparents to 1.8 children, simply speaking. With a life expectancy average of 76.6 years, the population begins to thin out progressively starting at about 55. This creates an oval effect when looking at populations.
5. It is tough to give descriptive words for each environment because each generation will determine what their environment will be like, but I will try
For a country with a lower fertility rate: reserved, conservative, wealthy (in comparison to other parts of the world), middle-class, developed, educated, 9 to 5, arts, transportation-heavy, stressed, little religion.
For a country with high fertility rates: strict, family-oriented, undeveloped, hungry, "primitive," transportation-lacking, young work force, lower-class, aided, sexually (over) active (?), religious.
2. The low fertility rate country was Australia with a rate of 1.8 children.
3. If for every couple, there is an average of 4 children, as in Botswana, than the ratio of children to parents is 2:1. That means the ratio of children to grandparents is 4:1 and so on. This creates a pyramid effect when looking at populations.
4. In a country with a lower fertility rate, like Australia, the opposite is true. There is a slightly unbalanced number of children to parents, with 1.8 children to 2 parents. That means there are 4 grandparents to 1.8 children, simply speaking. With a life expectancy average of 76.6 years, the population begins to thin out progressively starting at about 55. This creates an oval effect when looking at populations.
5. It is tough to give descriptive words for each environment because each generation will determine what their environment will be like, but I will try
For a country with a lower fertility rate: reserved, conservative, wealthy (in comparison to other parts of the world), middle-class, developed, educated, 9 to 5, arts, transportation-heavy, stressed, little religion.
For a country with high fertility rates: strict, family-oriented, undeveloped, hungry, "primitive," transportation-lacking, young work force, lower-class, aided, sexually (over) active (?), religious.
Thursday, May 8, 2008
Unit IV: Compendium II
I. Human Evolution
A. Origin of life
B. Biological evolution
C. Classification of humans
D. Evolution of hominids
E. Evolution of humans
II. Global ecology and human interferences
A. Nature of ecosystems
B. Energy flow
C. Global Biogeochemical cycles
III. Human Population, planetary resources and conservation
A. Human population growth
B. Human use of resources and pollution
C. Biodiversity
D. Working toward a sustainable society
DISCLAIMER: The opening paragraph of chapter 22 sums up a world view that does not coincide with my personal beliefs BASED ON AS MUCH SCIENTIFIC EVIDENCE AS THE THEORY PRESENTED IN CHAPTER 22. It poses the question, "Could a chemical evolution have produced the first cell(s) on the primitive earth. My answer to this question is: If it could, it hasn't been proven to. Let's recall the experiment that Carl Sagan hailed in his classic series, "Cosmos." He explained Stanley Miller's experiment that simulated the earth's early atmosphere. There were amino acids produced by these experiments, but an organic protein that led to biological synthesis was never produced. Even the means of amino acid synthesis is questionable as it was managed and produced thanks to the INTELLIGENCE of the scientist(s) behind the experiment. Later the experiments were deemed fairly irrelevant as the idea of what the atmosphere was made of changed. There has not yet been a proven piece of evidence that the events leading to life, believed by most scientists, is accurate or reliable, or FACTUAL. That is the first stumbling block to overcome before even moving on to the more advanced evolution proposed by chapter 22. If those are overcome than we can move on to more advanced hurdles that stand defiantly in the way of the simply-stated theory behind the writing within. Much less we start this chapter after the beginning of the earth...and thus our solar system...and thus the universe. The odds of the beginning of each one of these is beyond improbable, astronomically at odds, and impossible (mathematically speaking). Therefore the review herein is stressed to be nothing more than an unproven theory that does not agree with my own...or the empirical and evidential scientific process. We must admit that the origin of the universe...or earth...or its inhabitants cannot be empirically evident, as it already happened. Therefore it is up to us as REASONING beings to decide which theory is the most logical for the origin of the universe. I am confident in saying that I do not believe that the theory of Neo-Darwinian Evolution is the most logical.
A. Origin of life
The fundamental principle of biology states that all living things are made of cells. Every cell comes from a preexisting cell. Therefore the very first living thing must have come from non-living chemicals. The theory presented herein would simply state that there was a slow increase in the complexity of chemicals that would produce the first cells on the earth.
The sun and the planets are believed to have been formed over a 10-billion-year period. At 4.6 billion years ago the solar system was formed and in place. The earth's gravitational field is strong enough to have an atmosphere. With less mass there would be no atmosphere. IF MORE THAN CONDITIONS WOULD BE MUCH MORE LIKE THAT OF PLANETS LIKE VENUS...unlivable. Possibly, the early earth's atmosphere was formed by gases escaping from volcanoes. If that was the case the early atmosphere would have been made of: H2O, N2 and CO2, with small amounts of H2 and CO. This would have been a very hot atmosphere and water would have been in gas form, creating dense clouds. As the earth cooled the water became liquid. The oceans could have been formed by millions of years of heavy rainfall.
Small organic compounds might have been formed through the concentration of organic compounds and much available energy. Stanley Miller's experiment (spoke
of in DISCLAIMER) produced organic compounds by synthesizing an environment similar to that thought of to be the early earth's atmosphere.
RNA is thought to be the first basic macromolecule thought to carry out replication and continuation of organic synthesis, before DNA, the more stable protein complex, became dominant. This would have been some 3.5 billion years ago. The Protein-first hypothesis states that since amino acids join together when exposed to dry heat, perhaps they formed in puddles or something similar. When they returned to water they formed polypeptides which would aid in the forming cells.
Sidney Fox, who proposed the above stated hypothesis, also hypothesizes that lipid introduction to microspheres would have produced a lipid-protein that could carry on metabolism, but could reproduce. This cell would have been a fermenter since there was not free oxygen.
The supporters of these two different hypotheses about how DNA and, therefore, true cells could come about.
How the earth may have looked very
early on.
B. Biological Evolution
If cells evolved, the first cells would have been prokaryotic. These are cells without nuclei. From them would have come eukaryotes, then multicellular organisms and onward. Biological evolution is the process through which species change. Descent from the first cells could explain why all organisms have similar chemical makeup. Adaptations are the biological changes that help an organism survive. Charles Darwin formed the theory of evolution while spending time in the tropics. He concluded that lifeforms are so varied from place to place because of evolutionary adaptation. Fossils could be the best evidence for evolution. Paleontologists look to the stratum to determine or hypothesize the age of a creature. Transitional fossils would be those with characteristics of two different groups. One defended example is the archaeopteryx, which is a bird with reptile-like features. Because of the distribution of vegetation in various climates, scientists conclude that it also adapted to its environment. The similarity of bones in animals is another also used as evidence for evolution. Most proponents of evolution believe that natural selection was a very important factor in why we have the species we have today. Natural selection refers to the survival of organisms best suited to their environmen
t.
C. Classification of humans
Through classification we can determine which organisms are most alike. Organisms of the same domain have general characteristics alike. Those in the same genus have much more specific characteristics in common. DNA data is being used more and more to trace the ancestry of species. Humans are primates, mammals that have binocular vision, grasping hands, larger brains and lower reproductive rates. They have mobile and opposable limbs and digits. There are many similarities between the skeleton of humans and of chimpanzees. However important differences are why human walk upright and chimpanzees do not.
Human belong to the moderately general
class of mammals.
D. Evolution of hominids
According to the evolutionary tree all primates evolved from a common ancestor. According to it there was a common ancestor for monkeys apes and hominids 45 MYA (million years ago.) There was one for all apes about 15 MYA. Then one for African apes 7MYA. The split between
the ape and human lineage is thought to have occurred at that time. Humans couldn't have evolved from apes because they are contemporaries, but would have shared a common ancestor. Biologists do not agree on what the first hominid would be. Hominid features include the bipedal posture, larger brains and flat faces. Some of the fossil pieces thought to be related to hominids are those of the species Sahelanthropus tchadensis, Orrorin tugenesis and Ardipithecus kadabba.
Fossils are called "Homo" if the brain size is 600cm or larger, jaws and teeth resemble humans and tool use is evident. Homo habilis would be the first, dated between 2 and 1.9 MYA. They would have probably been omnivores. Since bones at their campsites have cut marks, they had tools. They probably used very crude rocks to do the work. Society and culture would have begun here if there was a cooperation between hunting and gathering. Speech and knowledge transmission were vital to this process. Homo erectus would have followed between 1.9 and .3 MYA. H. erectus would have had a larger brain and a flatter face.
Most scientists believe in the "Out-of-Africa" theory of human evolution: that homo sapiens evolved in Africa from homo erectus and then migrated. Neandertals are thought to be the another branch in the evolutionary chain. They would have had a larger brain than the modern human and would have been far more heavily muscled. Cro-Magnon DNA is supposed to be
very different from Neandertals to the point that there was no interbreeding. They may have lived side by side. They would have been such advanced hunters that they may have been responsible for the extinction of many large animals.
Humans are widely distributed and have many different anatomic features. Some believe that some of these differences may be adaptations to their environment. Others cannot be explained. All humans are extremely similar.
Though there are variations
all humans are very similar.
A. Origin of life
B. Biological evolution
C. Classification of humans
D. Evolution of hominids
E. Evolution of humans
II. Global ecology and human interferences
A. Nature of ecosystems
B. Energy flow
C. Global Biogeochemical cycles
III. Human Population, planetary resources and conservation
A. Human population growth
B. Human use of resources and pollution
C. Biodiversity
D. Working toward a sustainable society
DISCLAIMER: The opening paragraph of chapter 22 sums up a world view that does not coincide with my personal beliefs BASED ON AS MUCH SCIENTIFIC EVIDENCE AS THE THEORY PRESENTED IN CHAPTER 22. It poses the question, "Could a chemical evolution have produced the first cell(s) on the primitive earth. My answer to this question is: If it could, it hasn't been proven to. Let's recall the experiment that Carl Sagan hailed in his classic series, "Cosmos." He explained Stanley Miller's experiment that simulated the earth's early atmosphere. There were amino acids produced by these experiments, but an organic protein that led to biological synthesis was never produced. Even the means of amino acid synthesis is questionable as it was managed and produced thanks to the INTELLIGENCE of the scientist(s) behind the experiment. Later the experiments were deemed fairly irrelevant as the idea of what the atmosphere was made of changed. There has not yet been a proven piece of evidence that the events leading to life, believed by most scientists, is accurate or reliable, or FACTUAL. That is the first stumbling block to overcome before even moving on to the more advanced evolution proposed by chapter 22. If those are overcome than we can move on to more advanced hurdles that stand defiantly in the way of the simply-stated theory behind the writing within. Much less we start this chapter after the beginning of the earth...and thus our solar system...and thus the universe. The odds of the beginning of each one of these is beyond improbable, astronomically at odds, and impossible (mathematically speaking). Therefore the review herein is stressed to be nothing more than an unproven theory that does not agree with my own...or the empirical and evidential scientific process. We must admit that the origin of the universe...or earth...or its inhabitants cannot be empirically evident, as it already happened. Therefore it is up to us as REASONING beings to decide which theory is the most logical for the origin of the universe. I am confident in saying that I do not believe that the theory of Neo-Darwinian Evolution is the most logical.
A. Origin of life
The fundamental principle of biology states that all living things are made of cells. Every cell comes from a preexisting cell. Therefore the very first living thing must have come from non-living chemicals. The theory presented herein would simply state that there was a slow increase in the complexity of chemicals that would produce the first cells on the earth.
The sun and the planets are believed to have been formed over a 10-billion-year period. At 4.6 billion years ago the solar system was formed and in place. The earth's gravitational field is strong enough to have an atmosphere. With less mass there would be no atmosphere. IF MORE THAN CONDITIONS WOULD BE MUCH MORE LIKE THAT OF PLANETS LIKE VENUS...unlivable. Possibly, the early earth's atmosphere was formed by gases escaping from volcanoes. If that was the case the early atmosphere would have been made of: H2O, N2 and CO2, with small amounts of H2 and CO. This would have been a very hot atmosphere and water would have been in gas form, creating dense clouds. As the earth cooled the water became liquid. The oceans could have been formed by millions of years of heavy rainfall.
Small organic compounds might have been formed through the concentration of organic compounds and much available energy. Stanley Miller's experiment (spoke
of in DISCLAIMER) produced organic compounds by synthesizing an environment similar to that thought of to be the early earth's atmosphere.RNA is thought to be the first basic macromolecule thought to carry out replication and continuation of organic synthesis, before DNA, the more stable protein complex, became dominant. This would have been some 3.5 billion years ago. The Protein-first hypothesis states that since amino acids join together when exposed to dry heat, perhaps they formed in puddles or something similar. When they returned to water they formed polypeptides which would aid in the forming cells.
Sidney Fox, who proposed the above stated hypothesis, also hypothesizes that lipid introduction to microspheres would have produced a lipid-protein that could carry on metabolism, but could reproduce. This cell would have been a fermenter since there was not free oxygen.
The supporters of these two different hypotheses about how DNA and, therefore, true cells could come about.
How the earth may have looked very
early on.
If cells evolved, the first cells would have been prokaryotic. These are cells without nuclei. From them would have come eukaryotes, then multicellular organisms and onward. Biological evolution is the process through which species change. Descent from the first cells could explain why all organisms have similar chemical makeup. Adaptations are the biological changes that help an organism survive. Charles Darwin formed the theory of evolution while spending time in the tropics. He concluded that lifeforms are so varied from place to place because of evolutionary adaptation. Fossils could be the best evidence for evolution. Paleontologists look to the stratum to determine or hypothesize the age of a creature. Transitional fossils would be those with characteristics of two different groups. One defended example is the archaeopteryx, which is a bird with reptile-like features. Because of the distribution of vegetation in various climates, scientists conclude that it also adapted to its environment. The similarity of bones in animals is another also used as evidence for evolution. Most proponents of evolution believe that natural selection was a very important factor in why we have the species we have today. Natural selection refers to the survival of organisms best suited to their environmen
t.C. Classification of humans
Through classification we can determine which organisms are most alike. Organisms of the same domain have general characteristics alike. Those in the same genus have much more specific characteristics in common. DNA data is being used more and more to trace the ancestry of species. Humans are primates, mammals that have binocular vision, grasping hands, larger brains and lower reproductive rates. They have mobile and opposable limbs and digits. There are many similarities between the skeleton of humans and of chimpanzees. However important differences are why human walk upright and chimpanzees do not.
Human belong to the moderately general
class of mammals.
According to the evolutionary tree all primates evolved from a common ancestor. According to it there was a common ancestor for monkeys apes and hominids 45 MYA (million years ago.) There was one for all apes about 15 MYA. Then one for African apes 7MYA. The split between
the ape and human lineage is thought to have occurred at that time. Humans couldn't have evolved from apes because they are contemporaries, but would have shared a common ancestor. Biologists do not agree on what the first hominid would be. Hominid features include the bipedal posture, larger brains and flat faces. Some of the fossil pieces thought to be related to hominids are those of the species Sahelanthropus tchadensis, Orrorin tugenesis and Ardipithecus kadabba.Human, Darren Naish, at the family reunion
with artists' renditions of what some hominids
may have looked like.
E. Evolution of humanswith artists' renditions of what some hominids
may have looked like.
Fossils are called "Homo" if the brain size is 600cm or larger, jaws and teeth resemble humans and tool use is evident. Homo habilis would be the first, dated between 2 and 1.9 MYA. They would have probably been omnivores. Since bones at their campsites have cut marks, they had tools. They probably used very crude rocks to do the work. Society and culture would have begun here if there was a cooperation between hunting and gathering. Speech and knowledge transmission were vital to this process. Homo erectus would have followed between 1.9 and .3 MYA. H. erectus would have had a larger brain and a flatter face.
Most scientists believe in the "Out-of-Africa" theory of human evolution: that homo sapiens evolved in Africa from homo erectus and then migrated. Neandertals are thought to be the another branch in the evolutionary chain. They would have had a larger brain than the modern human and would have been far more heavily muscled. Cro-Magnon DNA is supposed to be
very different from Neandertals to the point that there was no interbreeding. They may have lived side by side. They would have been such advanced hunters that they may have been responsible for the extinction of many large animals.Humans are widely distributed and have many different anatomic features. Some believe that some of these differences may be adaptations to their environment. Others cannot be explained. All humans are extremely similar.
Though there are variations
all humans are very similar.
II. Global Ecology and Human Interferences
A. Nature of ecosystems
The Biosphere is every where on earth where organisms are found. It is really one giant ecosystem, however there are divisions of ecosystems based on temperature and rainfall, for terrestrial ecosystems, or biomes. Some are: tropical rain forest, tropical grassland, temperate forest of grassland, taiga, desert and tundra. There are two types of aquatic ecosystems, saltwater and freshwater. The freshwater ecosystems are standing water and running water.
Biotic components of an ecosystem are the living organisms. Autotrophs are organisms that produce their own food from inorganic nutrients and outside
energy. These are most plants and algae. Heterotrophs need a source of organic nutrients. Some are herbivores, that only feed on plants or algae. Some are carnivores, that is meat eaters. Some are both; these are called omnivores. Other still are detritus feeders, which means they feed on the decomposing part of organic matter. Some of these are called decomposers because their feeding breaks down and releases nutrients for plant use. A niche is an organisms role in an ecosystem. Its interaction is part of the whole of the ecosystem. Every ecosystem is characterized by two factors, energy flow and chemical cycling. Nutrients absorbed or made by producers is passed on to consumers (heterotrophs). Then it is absorbed by decomposers who will return them to the soil or atmosphere where they will again be absorbed by the producers.
The Rain forest is the wettest of
all terrestrial ecosystems.
B. Energy flow
A food web is a diagram that describes the feeding relationships (trophic) of organisms in an ecosystem. They give us a picture of the energy flow. A graz
ing food web describes that which begins with producers and ends with the top carnivores. A detrital food web shows that which starts with detritus and moves to decomposers and on up to the top carnivores. If a diagram shows a single path of energy flow it is called a food chain. A trophic level contains all the organisms that feed at a single link in the food chain. Only about 10% of the energy of one trophic level is available to the next level. That is why an ecosystem can only support so many carnivores. Because of the loss of energy at each level it can be described as an ecological pyramid. It can also be described this way due to the amount of organisms and their weight, or biomass, at each level.
A food web of an temperate forest
ecosystem.
C. Global biogeochemical cycles
All organisms require various organic and/or inorganic nutrients. These chemicals circulate through biotic and geological components. This can either be done in a gaseous or a sedimentary (taken from soil by producers and passed on) cycle. Some different components of cycling are reservoirs or exchange pools. Human activities upset the normal balance by removing chemicals from reservoirs and exchange pools.
The hydrologic cycle, or water cycle, works like this: Evaporation occurs. Once in the atmosphere the water vapor condenses and falls as precipitation. Runoff makes water flow into lakes, streams, wetlands and the ocean. Other water percolates into the soil and some goes deep down into aquifers, which return in springs or wells.
Humans interfere by: withdrawing water from aquifers, clearing vegetation and building which prevents percolation, and pollute water and add sewage and chemicals.
The carbon cycle works in this way: Producers take carbon dioxide from the air and through photosynthesis. They turn it into valuable nutrients which are consumed by auto and heterotrophs. When organisms respire carbon is returned to the atmosphere as carbon dioxide and then is cycled back to plants. Dead and living organisms are reservoirs for carbon. Some of these are fossil fuels from plant and animal remains that have been converted over time.
Human interference has caused more CO2 to be deposited in the atmosphere than released. There is practically twice as much CO2 being released as there already has been in the atmosphere. The release of certain gases like NO and CH4 as well as CO2 has caused a change in climate that may make the earth's temperature rise, among other things. It is often called by its archaic name: global warming. Now it is mostly referred to as climate change, because much more is happening than a rise in temperature.
Nitrogen makes up about 78% of the atmosphere. Plants do not utilize N2 and it can limit the amount of growth in an ecosystem. It does, however use ammonium. N2 is converted to ammonium by some bacteria and it is used by the host plants of these bacteria. Plants also use nitrates, NO3, Nitrates are made when high energy occurrences make them bind with oxygen. Soil bacteria can also convert NH4 (ammonium) into No2, nitrite, which is converted by other bacteria into nitrate. During assimilation plants turn the nitrate into proteins and nucleic acids. Dentrification is the return of nitrate to N2 which counterbalances nitrogen fixation. Human activities double the fixation rate. The runoff enters lakes and rivers where overgrowth occurs. When the overgrowth dies off the decomposers will boom which ends in a large fish kill. The burning of fossil fuels has put too much nitrogen oxides and sulfur dioxide into the air. They attach to water vapor and
come down in rainfall. The acidic rain lowers crop yields and eats the marble, metal and stonework. These gases also combine with sunlight to make smog which doesn't allow the proper escape of pollutants out of the atmosphere.
Phosphorus is released through geological upheaval and through the slow weathering of rocks. It is used by plants to make ATP, phospholipids and nucleotides for DNA and RNA. Consumers get it from producers. Through decay phosphates are once again available to producers. Its scarcity controls the size of populations.
Humans boost the supply of phosphate through mining. This also causes overgrowth in waterways. The pollutants produced are very dangerous because they are not easily degraded and become more and more concentrated as they pass through the food chain. The oceans are most greatly affected by all the pollutions, where many species of fish are on the brink of extinction.
A. Nature of ecosystems
The Biosphere is every where on earth where organisms are found. It is really one giant ecosystem, however there are divisions of ecosystems based on temperature and rainfall, for terrestrial ecosystems, or biomes. Some are: tropical rain forest, tropical grassland, temperate forest of grassland, taiga, desert and tundra. There are two types of aquatic ecosystems, saltwater and freshwater. The freshwater ecosystems are standing water and running water.
Biotic components of an ecosystem are the living organisms. Autotrophs are organisms that produce their own food from inorganic nutrients and outside
energy. These are most plants and algae. Heterotrophs need a source of organic nutrients. Some are herbivores, that only feed on plants or algae. Some are carnivores, that is meat eaters. Some are both; these are called omnivores. Other still are detritus feeders, which means they feed on the decomposing part of organic matter. Some of these are called decomposers because their feeding breaks down and releases nutrients for plant use. A niche is an organisms role in an ecosystem. Its interaction is part of the whole of the ecosystem. Every ecosystem is characterized by two factors, energy flow and chemical cycling. Nutrients absorbed or made by producers is passed on to consumers (heterotrophs). Then it is absorbed by decomposers who will return them to the soil or atmosphere where they will again be absorbed by the producers.The Rain forest is the wettest of
all terrestrial ecosystems.
B. Energy flow
A food web is a diagram that describes the feeding relationships (trophic) of organisms in an ecosystem. They give us a picture of the energy flow. A graz
ing food web describes that which begins with producers and ends with the top carnivores. A detrital food web shows that which starts with detritus and moves to decomposers and on up to the top carnivores. If a diagram shows a single path of energy flow it is called a food chain. A trophic level contains all the organisms that feed at a single link in the food chain. Only about 10% of the energy of one trophic level is available to the next level. That is why an ecosystem can only support so many carnivores. Because of the loss of energy at each level it can be described as an ecological pyramid. It can also be described this way due to the amount of organisms and their weight, or biomass, at each level.A food web of an temperate forest
ecosystem.
All organisms require various organic and/or inorganic nutrients. These chemicals circulate through biotic and geological components. This can either be done in a gaseous or a sedimentary (taken from soil by producers and passed on) cycle. Some different components of cycling are reservoirs or exchange pools. Human activities upset the normal balance by removing chemicals from reservoirs and exchange pools.
The hydrologic cycle, or water cycle, works like this: Evaporation occurs. Once in the atmosphere the water vapor condenses and falls as precipitation. Runoff makes water flow into lakes, streams, wetlands and the ocean. Other water percolates into the soil and some goes deep down into aquifers, which return in springs or wells.
Humans interfere by: withdrawing water from aquifers, clearing vegetation and building which prevents percolation, and pollute water and add sewage and chemicals.
The carbon cycle works in this way: Producers take carbon dioxide from the air and through photosynthesis. They turn it into valuable nutrients which are consumed by auto and heterotrophs. When organisms respire carbon is returned to the atmosphere as carbon dioxide and then is cycled back to plants. Dead and living organisms are reservoirs for carbon. Some of these are fossil fuels from plant and animal remains that have been converted over time.
Human interference has caused more CO2 to be deposited in the atmosphere than released. There is practically twice as much CO2 being released as there already has been in the atmosphere. The release of certain gases like NO and CH4 as well as CO2 has caused a change in climate that may make the earth's temperature rise, among other things. It is often called by its archaic name: global warming. Now it is mostly referred to as climate change, because much more is happening than a rise in temperature.
Nitrogen makes up about 78% of the atmosphere. Plants do not utilize N2 and it can limit the amount of growth in an ecosystem. It does, however use ammonium. N2 is converted to ammonium by some bacteria and it is used by the host plants of these bacteria. Plants also use nitrates, NO3, Nitrates are made when high energy occurrences make them bind with oxygen. Soil bacteria can also convert NH4 (ammonium) into No2, nitrite, which is converted by other bacteria into nitrate. During assimilation plants turn the nitrate into proteins and nucleic acids. Dentrification is the return of nitrate to N2 which counterbalances nitrogen fixation. Human activities double the fixation rate. The runoff enters lakes and rivers where overgrowth occurs. When the overgrowth dies off the decomposers will boom which ends in a large fish kill. The burning of fossil fuels has put too much nitrogen oxides and sulfur dioxide into the air. They attach to water vapor and
come down in rainfall. The acidic rain lowers crop yields and eats the marble, metal and stonework. These gases also combine with sunlight to make smog which doesn't allow the proper escape of pollutants out of the atmosphere.Phosphorus is released through geological upheaval and through the slow weathering of rocks. It is used by plants to make ATP, phospholipids and nucleotides for DNA and RNA. Consumers get it from producers. Through decay phosphates are once again available to producers. Its scarcity controls the size of populations.
Humans boost the supply of phosphate through mining. This also causes overgrowth in waterways. The pollutants produced are very dangerous because they are not easily degraded and become more and more concentrated as they pass through the food chain. The oceans are most greatly affected by all the pollutions, where many species of fish are on the brink of extinction.
Acid deposition has killed these trees.
III. Human Population, Planetary Resources and Conservation
A. Human population growth
Since about 1750 the growth rate of the the human population has increased steadily. Then around the 1930's the population spiked in the less-developed countries (LDCs.)This is very different than the population growth in more-developed countries (MDCs) where growth is modest and people enjoy a good living standard. In LDCs most people live in poverty.
Between 1850 and 1950 the MDCs doubled their populations, thanks to modern medicine and new public health standards. Then there was a decline in birth rates around 1950 so population increase has been slowed. The MDCs have a growth rate of about 0.1% as a whole. The U.S. however, has a growth rate of about 0.6%. This partly due to constant migration to the U.S. from other countries. There is no leveling off to the
U.S. population growth. In the LDCs death rates decreased drastically after World War II, thanks to modern medicine. The birth rate remained high. Between 1960 and 1965 the growth rate was about 2.5%, the height of growth rate. The collective rate is about 1.6% now. Between 2002 and 2050 the population of the LDCs is expected to go up to about 8 billion. Some of this will happen in Africa, but most will be in Asia, because so many in Africa are dying of AIDS. Asia has been and will experience water loss, loss of biodiversity and urban pollution. Because more women are reaching reproductive years, than women leaving them, the population is increasing in the LDCs.
Resources are any biotic or abiotic substance that helps meet needs. Nonrenewable resources are limited. They include land, fossil fuels and minerals. These sources will run out. Renewable resources are naturally replenished. However some of these, such as animals, have population thresholds, below which they are unrecoverable. Pollution is a side effect of some resource consumption. It is an negative alteration of the environment. The amount of pollution put out is proportional to the size of the population. On an average there 83 persons living per square mile on the planet, including all the uninhabitable parts of the world!About 40% of the population lives near a coastline. In the US more than half the population live near the coast. This leads to beach erosion, which decreases marine population and decreases the buffer zone for storms. The loss of wetlands, for example, contributed to the devastation caused by Hurricane Katrina. Forty percent of the earth's land is desert. Desertification is the conversion of semiarid land to desert. It usually begins through the overgrazing of animals on semiarid land. Estimations say that 75% of all rangeland is in danger of desertification. Rain forest land is also subject to desertification when it is deforested. The soil is not suitable for long-term farming, because the nutrients are all in the current vegetation. When it is removed the soil loses its fertility quickly.
Though clean drinking water should be the right of all people, most freshwater utilized by industry and agriculture. Seventy percent of all freshwater is used to irrigate crops. The freshwater demand is due in large to these activities. In MDCs more water is used for bathing, cooking, flushing toilets and watering lawns than drinking. Damming has caused extensive flow loss on most major rivers of the world. Sometimes the amount of water lost to evaporation and seepage from dams is equal to the amount made available. An absurd amount of water has been used out of aquifers, supply that has been there for possibly thousands of years. The High Plains Aquifer has been depleted of over half of its water supply. Subsidence, settling of the soil, occurs as a result. This causes sinkholes. By 2025 2/3 of the world's population may be living in areas with serious water shortage. Some solutions may help. Planting drought-resistant and saltwater-resistant crops. Using drip irrigation saves about 50% more water than sprinkler methods. Farmers have little incentive to switch, though. Adopting new conservation plans could help industries cut water demands by more than half!
Food supply generally comes from three activities: growing crops, raising animals and fishing the seas. Modern farming methods have increased food production but have had damaging effects. Some of these are pollution from fertilizers, cancer-causing agents and loss of soil fertility from pesticides, water loss, pollution and loss of fuel sources. Some helpful practices minimize harm. Intercropping can cause the use of less fertilizers. Contour farming preserves top soil and water. Because livestock feed on most of the crops produced, at least in the US, the consumption of less meat and more vegetables will greatly reduced the poor farming practices and fuel consumption of both industries.
Sources of energy are integral to modern society. Some are renewable and some are not. Environmental degradation occurs due to use of nonrenewable energy sources. About 75% of the world's energy comes from fossil fuels. Nuclear power is also nonrenewable and its effects are dangerous. Persons in the MDCs use as much energy in one day as persons in LDCs do in one year! Most of this is fossil fuels, of course. Climate change and the "greenhouse effect" have been caused due to the burning of fossil fuels and clearing of forests. Some effects could be: the major rise of the oceans, loss of wetlands, danger to coastal cities and loss of coral reefs. Renewable energy sources include: hydropower (if used correctly can produce plenty of energy without detrimental effects to the environment.), geothermal energy, wind power and solar energy.
Minerals are nonrenewable raw materials like fossil fuels, sand, gravel, phosphate and metals. Heavy metals are detrimental to human health and their hazrdous wastes must be discarded carefully. Strip mining for minerals makes the land devoid of vegetation and washes harmful substances into water supplies. The most common contaminates made by mining and other industrial products are heavey metals and synthetic organic chemicals.
C. Biodiversity
Biodiversity is the variety of life through numbers of different species. Biodiversity is in great crisis as there are staggering predictions of extinction of species. Habitat loss is a major player in loss of biodiversity.Human occupation and deforesting are causing habitat loss especially in the tropical rain forests and coral reefs. Alien species, those introduced into new ecosystems, often drive out the native species. Pollution causes: acid deposition, climate change, ozone depletion and directly kills animals when wastes put synthetic organic chemicals directly into the food supply. Overexploitation, that is the over extraction of species to a devastating reduction, is threatening extinction of species of plants and animals. Disease from domestic animal encroachment is fatal to local wildlife. Some extinctions may occur simply to disease.
Biodiversity is very important to the environment and to the population. Many plants are important for medicinal reasons. There are an estimated 328 types of drugs yet to be discovered in plants of the tropical rain forests. Bacterium play roles in cure and also in research of their damaging effects. Animals that carry them are important to researchers. Wild crops are still important because they contain different genetic makeup that may be important to virus resistance or have natural pesticides. Natural predators and pest control are preferable to chemical pesticides. Flowering plants need certain birds, bats and insects to pollinate them. Some forested areas are more valuable for the trees' o
utput (fruit, wax) than their timber. The one is a renewable source, the other is not. It is more economical to save ecosystems rather than individual species. Disposing of waste, properly, is one method. Using partially treated wastewater lets soil bacteria ensure a complete cleansing of wastes. Using wetlands to breakdown pollutants is also efficient. There is no substitute for freshwater. It is absolutely necessary. Using it effectively through forest and wetland protection will ensure its availability. Soil erosion is curable simply by keeping the ecosystem intact. Trees and plants will regulate climate when allowed.
Urban sprawl endangers the local wildlife.
D. Working toward a sustainable society
Sustainable societies could always provide the same amount of goods and services for future generations. The MDCs excessive consumption as well as the population growth of the LDCs stresses the environment. Wasteful practices are causing great harm to the environment. Urban sprawl is causing loss of habitat. More natural practices can help us reach a sustainable society. Nature gives us clues. It uses only solar energy as its renewable source. Cycles ensure the return of materials to use. Following these cues and preserving the natural ecosystems is integral to a sustainable society. Certain practices must be done in areas from agriculture to enterprise. Efficient cars, that are light and gas thrifty, are one change we could make to approve efficiency of transportation and sustainability. Both city and country need to be sustainable because they depend on each other for goods and services. In rural areas the emphasis should be on preservation as much as possible. Preserving native grasses and planting trees is integral to the preservation of top soil. Some measures that can be taken are:
using cover crops between cash crops, multiuse farming, composting and organic gardening, using drip irrigation and retention ponds, increasing the planting of cultivars, using precision farming, using natural pest control, planting a variety of species, planting multipurpose trees, maintaining and restoring wetlands, using renewable forms of energy and support local farmers, fisherman and feed stores
Some possible ways to help make cities sustainable are:
using energy efficient transportation, solar and geothermal energy sources for heat and seawater air-conditioning, Using green roofs, or wild gardens on the tops of buildings for temperature control/food/runoff, Use sediments, artificial wetlands and holding ponds for storm-water, plant native species to attract natural wildlife and use less water, create greenbelts using walking and biking paths, revitalize old sections before building new ones, use efficient lighting fixtures and promote sustainability through recycling business equipment and using low-maintenance building materials.
A combination green roof and park.
With better assessment of funds with consideration of well-being and environmental impact we may better plan for the future and direct energies where they would be best used.
III. Human Population, Planetary Resources and Conservation
A. Human population growth
Since about 1750 the growth rate of the the human population has increased steadily. Then around the 1930's the population spiked in the less-developed countries (LDCs.)This is very different than the population growth in more-developed countries (MDCs) where growth is modest and people enjoy a good living standard. In LDCs most people live in poverty.
Between 1850 and 1950 the MDCs doubled their populations, thanks to modern medicine and new public health standards. Then there was a decline in birth rates around 1950 so population increase has been slowed. The MDCs have a growth rate of about 0.1% as a whole. The U.S. however, has a growth rate of about 0.6%. This partly due to constant migration to the U.S. from other countries. There is no leveling off to the
U.S. population growth. In the LDCs death rates decreased drastically after World War II, thanks to modern medicine. The birth rate remained high. Between 1960 and 1965 the growth rate was about 2.5%, the height of growth rate. The collective rate is about 1.6% now. Between 2002 and 2050 the population of the LDCs is expected to go up to about 8 billion. Some of this will happen in Africa, but most will be in Asia, because so many in Africa are dying of AIDS. Asia has been and will experience water loss, loss of biodiversity and urban pollution. Because more women are reaching reproductive years, than women leaving them, the population is increasing in the LDCs.Because of the high birth rate in countries like
Burma, the country has a young population
that will continue to grow.
B. Human Use of Resources and PollutionBurma, the country has a young population
that will continue to grow.
Resources are any biotic or abiotic substance that helps meet needs. Nonrenewable resources are limited. They include land, fossil fuels and minerals. These sources will run out. Renewable resources are naturally replenished. However some of these, such as animals, have population thresholds, below which they are unrecoverable. Pollution is a side effect of some resource consumption. It is an negative alteration of the environment. The amount of pollution put out is proportional to the size of the population. On an average there 83 persons living per square mile on the planet, including all the uninhabitable parts of the world!About 40% of the population lives near a coastline. In the US more than half the population live near the coast. This leads to beach erosion, which decreases marine population and decreases the buffer zone for storms. The loss of wetlands, for example, contributed to the devastation caused by Hurricane Katrina. Forty percent of the earth's land is desert. Desertification is the conversion of semiarid land to desert. It usually begins through the overgrazing of animals on semiarid land. Estimations say that 75% of all rangeland is in danger of desertification. Rain forest land is also subject to desertification when it is deforested. The soil is not suitable for long-term farming, because the nutrients are all in the current vegetation. When it is removed the soil loses its fertility quickly.
Though clean drinking water should be the right of all people, most freshwater utilized by industry and agriculture. Seventy percent of all freshwater is used to irrigate crops. The freshwater demand is due in large to these activities. In MDCs more water is used for bathing, cooking, flushing toilets and watering lawns than drinking. Damming has caused extensive flow loss on most major rivers of the world. Sometimes the amount of water lost to evaporation and seepage from dams is equal to the amount made available. An absurd amount of water has been used out of aquifers, supply that has been there for possibly thousands of years. The High Plains Aquifer has been depleted of over half of its water supply. Subsidence, settling of the soil, occurs as a result. This causes sinkholes. By 2025 2/3 of the world's population may be living in areas with serious water shortage. Some solutions may help. Planting drought-resistant and saltwater-resistant crops. Using drip irrigation saves about 50% more water than sprinkler methods. Farmers have little incentive to switch, though. Adopting new conservation plans could help industries cut water demands by more than half!
Food supply generally comes from three activities: growing crops, raising animals and fishing the seas. Modern farming methods have increased food production but have had damaging effects. Some of these are pollution from fertilizers, cancer-causing agents and loss of soil fertility from pesticides, water loss, pollution and loss of fuel sources. Some helpful practices minimize harm. Intercropping can cause the use of less fertilizers. Contour farming preserves top soil and water. Because livestock feed on most of the crops produced, at least in the US, the consumption of less meat and more vegetables will greatly reduced the poor farming practices and fuel consumption of both industries.
Sources of energy are integral to modern society. Some are renewable and some are not. Environmental degradation occurs due to use of nonrenewable energy sources. About 75% of the world's energy comes from fossil fuels. Nuclear power is also nonrenewable and its effects are dangerous. Persons in the MDCs use as much energy in one day as persons in LDCs do in one year! Most of this is fossil fuels, of course. Climate change and the "greenhouse effect" have been caused due to the burning of fossil fuels and clearing of forests. Some effects could be: the major rise of the oceans, loss of wetlands, danger to coastal cities and loss of coral reefs. Renewable energy sources include: hydropower (if used correctly can produce plenty of energy without detrimental effects to the environment.), geothermal energy, wind power and solar energy.
Minerals are nonrenewable raw materials like fossil fuels, sand, gravel, phosphate and metals. Heavy metals are detrimental to human health and their hazrdous wastes must be discarded carefully. Strip mining for minerals makes the land devoid of vegetation and washes harmful substances into water supplies. The most common contaminates made by mining and other industrial products are heavey metals and synthetic organic chemicals.
C. Biodiversity
Biodiversity is the variety of life through numbers of different species. Biodiversity is in great crisis as there are staggering predictions of extinction of species. Habitat loss is a major player in loss of biodiversity.Human occupation and deforesting are causing habitat loss especially in the tropical rain forests and coral reefs. Alien species, those introduced into new ecosystems, often drive out the native species. Pollution causes: acid deposition, climate change, ozone depletion and directly kills animals when wastes put synthetic organic chemicals directly into the food supply. Overexploitation, that is the over extraction of species to a devastating reduction, is threatening extinction of species of plants and animals. Disease from domestic animal encroachment is fatal to local wildlife. Some extinctions may occur simply to disease.
Biodiversity is very important to the environment and to the population. Many plants are important for medicinal reasons. There are an estimated 328 types of drugs yet to be discovered in plants of the tropical rain forests. Bacterium play roles in cure and also in research of their damaging effects. Animals that carry them are important to researchers. Wild crops are still important because they contain different genetic makeup that may be important to virus resistance or have natural pesticides. Natural predators and pest control are preferable to chemical pesticides. Flowering plants need certain birds, bats and insects to pollinate them. Some forested areas are more valuable for the trees' o
utput (fruit, wax) than their timber. The one is a renewable source, the other is not. It is more economical to save ecosystems rather than individual species. Disposing of waste, properly, is one method. Using partially treated wastewater lets soil bacteria ensure a complete cleansing of wastes. Using wetlands to breakdown pollutants is also efficient. There is no substitute for freshwater. It is absolutely necessary. Using it effectively through forest and wetland protection will ensure its availability. Soil erosion is curable simply by keeping the ecosystem intact. Trees and plants will regulate climate when allowed.Urban sprawl endangers the local wildlife.
Sustainable societies could always provide the same amount of goods and services for future generations. The MDCs excessive consumption as well as the population growth of the LDCs stresses the environment. Wasteful practices are causing great harm to the environment. Urban sprawl is causing loss of habitat. More natural practices can help us reach a sustainable society. Nature gives us clues. It uses only solar energy as its renewable source. Cycles ensure the return of materials to use. Following these cues and preserving the natural ecosystems is integral to a sustainable society. Certain practices must be done in areas from agriculture to enterprise. Efficient cars, that are light and gas thrifty, are one change we could make to approve efficiency of transportation and sustainability. Both city and country need to be sustainable because they depend on each other for goods and services. In rural areas the emphasis should be on preservation as much as possible. Preserving native grasses and planting trees is integral to the preservation of top soil. Some measures that can be taken are:
using cover crops between cash crops, multiuse farming, composting and organic gardening, using drip irrigation and retention ponds, increasing the planting of cultivars, using precision farming, using natural pest control, planting a variety of species, planting multipurpose trees, maintaining and restoring wetlands, using renewable forms of energy and support local farmers, fisherman and feed stores
Some possible ways to help make cities sustainable are:
using energy efficient transportation, solar and geothermal energy sources for heat and seawater air-conditioning, Using green roofs, or wild gardens on the tops of buildings for temperature control/food/runoff, Use sediments, artificial wetlands and holding ponds for storm-water, plant native species to attract natural wildlife and use less water, create greenbelts using walking and biking paths, revitalize old sections before building new ones, use efficient lighting fixtures and promote sustainability through recycling business equipment and using low-maintenance building materials.
A combination green roof and park.Tuesday, May 6, 2008
Unit IV: Compendium I
I. Reproductive System
A. The Life Cycle
B. Male Reproductive System
C.Female Reproductive System
D. Female Hormone Levels
E. Control of Reproduction
F. STDs
II. Development and Aging
A. Fertilization
B. Pre-embryonic/Embryonic Development
C. Fetal Development
D. Pregnancy and Birth
E. Development After Birth
A. The life cycle
Puberty is a sequence in which a person becomes sexually mature. Puberty is usually completed between 11 and 13 for girls and between 14 and 16 for boys. The reproductive system is the one system of the body that differs greatly between males and females. Male reproductive organs (testes) produce sperm. Female reproductive organs (ovaries) produce eggs
. In men the sperm are transported through the penis. Females transport the eggs to the uterus. The penis delivers sperm to the vagina through intercourse. The vagina will also be the birth canal. The uterus holds the developing fertilized egg. Both the testes and the ovaries produce sex hormones. The respective hormones give masculine or feminine qualities.
Mitosis duplicates our 46 chromosomes before dividing. However, in meiosis, which only occurs in the testes and ovaries for reproduction, the diploid number of chromosomes is reduced to twenty three. This way when the sperm fertilizes the egg, the zygote (or new cell) has 46 chromosomes, instead of the number doubling each generation.
The testes are the main sex organ (gonads). They are paired and they found in the sacs of the scrotum. When sperm is produced it is stored for maturation in the epididymis. Once mature the sperm enters a vas deferens. They may be stored here for a time. The vas deferentia wrap around the bladder and empty into an ejaculatory duct. These empty into the urethra. Sperm leave the penis in semen during ejaculation. The semen carries secretions from the prostate, bulbourethral glands and the seminal vesicles. The seminal fluid contains nutrients, chemicals and sugars. All are important to sperm energy and transportation.
The penis is the organ of male intercourse. This consists of a shaft and a tip called the glans penis. Erectile tissue contains spaces for blood. This spongy tissue fills with blood when stimulated by NO (nitric oxide) and cGMP (cyclic guanosine monophosphate). The veins that take away the blood are compressed and the penis becomes erect. A sphincter closes off the bladder which keeps urine from entering the urethra. As stimulation increases seminal fluid enter the urethra and the glands inject secretions. Rhythmic muscle contractions push the seminal fluid out of the urethra. This is ejaculation. This is one aspect of the male orgasm (sensations, both physical and psychological that occur at the climax of sexual intercourse.) The penis becomes flaccid again after ejaculation or after loss of sexual arousal.
Testes descend into the scrotum from the abdominal cavity during puberty. This is important because the temperature of the abdominal cavity is too high to produce sperm. A testis is made up of compartments called lobules. Each contain one to three seminiferous tubules. Inside spermatogenesis (production of sperm) is occurring. The original sperm cell for spermatogenesis is the spermagonia. It divides into two primary spermocytes through mitosis. Te secondary spermocytes are the meiosis division of primary spermocytes. Each secondary spermocyte becomes two early spermatids. When these
mature they become sperm. The process is nourished and regulated by sertoli cells. The process takes about 74 days. The parts of a mature sperm are the head, the middle piece and the tail. The head contains a nucleus and enzymes needed to penetrate the egg. The tail acts as a flagellum.
The hypothalamus is in control of hormone release and therefore testes' function. It secretes a hormone called gonadotropin-releasing hormone (GnRH.) This stimulates the petuitary gland to secrete the gonadotropic hormones FSH and LH. FSH promotes the production of sperm when found in males. LH controls testosterone production when found in males. Testosterone is essential for the development of the male reproductive organs. Testosterone also contributes to other distinctive characteristics of males (i.e. they tend to be taller, hairier and broader than females.)
The female gonads are the ovaries. They are also paired. They produce eggs. The oviducts, or fallopian tubes extend from the uterus to the ovaries. When an egg bursts from an ovary it is swept into the fallopian tube by its finger-like projections called fimbriae. The egg is then propelled by ciliary movement and muscle contraction to the uterus. An egg will generally live only 6-24 hours without being fertilized. Fertilization and zygote formation take place in the oviduct, normally. The developing embryo wil usually arrive at the uterus after several days. It will then embed in the uterine lining. The uterus is a muscular organ with thick walls. It is about the size and shape of a pear. The cervix, at the bottom of the uterus, joins almost a right angle. Development of the embryo and fetus takes place in the uterus. It starts at only about 5cm wide but can grow to 30cm for the development of a fetus.The endometrium, which lines the uterus, is essential to the formation of placenta, which nourishes the fetus. A small opening in the cervix leads to the vaginal canal. The vagina is a tube that is functional for intercourse (for fertilization) and as the birth canal. It also is the exit for menstrual flow.
The vulva is the term for the collective of external female genitalia. Two large, hair-covered fold of skin called the labia majora extend back from the mons pubis, a fatty area under the pubic hair. Two small folds lay just inside the labia majora called the labia minora. They extend from the vaginal opening to form a foreskin for the glans clitoris. The clitoris is contains erectile tissue that fills with blood when aroused. The cleft between the labia minora contains the urethra and the vaginal opening. The urinary and sexual systems, unlike in males, are separate.
The labia minora, vaginal wall and clitoris become engorged with blood during stimulation. The breasts also swell and the nipples become erect. The labia majora enlarge as well. The vagina is lubricated by glands that secrete mucus and fluid. The clitoris is what is actually stimulated in sexual intercourse and can swell to two to three times its normal size. Orgasms occur at the height of sexual response which causes the walls of the vagina and uterus to contract rhythmically. There is no refractory period for females after orgasms and can have many in one sexual experience.
D. Female hormone levels
An ovary has many follicles, each containing an immature egg called an oocyte. At puberty a female will have somewhere between 300,000-400,000 follicles. A very small number of these will ever mature. During the reproductive years a female will only produce one egg a month. The follicle goes through three different stages and then back, in what is called the ovarian cycle. The primary follicle (stage 1) contains epithelial cells that surround an oocyte. The secondary follicle (stage 2) surrounds the oocyte with follicular fluid and washes it. The vesicular follicle (stage 3) continues to fill with fluid until it balloons the ovary wall. When an oocyte goes through meiosis it reduces after the first stage into the secondary oocyte and the polar body, which simply holds the discarded chromosomes. If fertilize the 14th day of a 28 day cycle. If fertilization does not occur then a new cycle will begin with menstruation.
Estrogen is mainly responsible for secondary functions in women, such as fat distribution (curves and breasts) and, generally, less body hair than men. Progesterone is also involved in breast development and more hormones are also involved in milk production. Between the ages of 45 and 55 the ovarian cycle will, likely, cease. This is called menopause. The ovaries no longer produce estrogen or progesterone. Completion of menopause d the secondary oocyte will undergo meiosis 2. Before any of this occurs the oocyte is released from the ovary by bursting from the vesicular follicle. This is called ovulation. When the vesicular follicle has released the oocyte it becomes a corpus luteum which is a gland-like structure. If the egg is not fertilized the corpus luteum disinegrates. The ovary also produces the sex hormones. The corpus luteum will produce progesterone while the primary and secondary follicles produce estrogen. Like in males, females produce GnRH (hypothalamus), FSH ans LH (pituitary)The last two stimulate the ovarian cycle in females. Gonadotropic hormones occur intermittently throughout the cycle. Through the feedback process the hormone levels cause ovulation onis usually considered after a year with no menstruation period. The 28-day cycle, or uterine cycle, is marked by four definite stages. In the first the endometrium disintegrates and causes the blood vessels to rupture. Blood and tissue, called the menses, passes out of the vagina. This is known as menstruation. In the second stage the endometrium thickens with the increased production of estrogen. In the third, usually on day 14, ovulation occurs. The last period, increased production of progesterone causes the endometrium to double or triple in thickness. The endometrium is now ready to receive a developing embryo. If this does not happen, sex hormones will decrease and cause the endometrium to break down again.
During intercourse many dsperm will travel to
the oviduct where the egg is. Only one will fertilize the egg. If it becomes a zygote it will begin to develop on its way down the oviduct to the uterus. It will attach to the endometrium and implant. Pregnancy has now begun. The placenta sustains the embryo. This is where exchange occurs between maternal and fetal tissue. The placenta will initially produce the hormone HCG. Detection of it in the bloodstream or urine signifies pregnancy. Increased production of progesterone will signal the ceasing of follicle beginning. The endometrium does not break down resulting in no menstruation.
Birth control methods are used to decrease the likelihood of reproduction. The most reliable method is abstinence, or the refrain from sexual intercourse. It is also the most reliable inhibitor of sexually transmitted diseases (STDs.) There are a number of birth control methods and many used are contraceptives. These are devices or medications that inhibit pregnancy. Some are male and female condoms, birth control pills, implants (usually contain hormones), and many others.
Infertility is the inability to become pregnant after a year of intercourse. About 15% of all couple are infertile. The cause in 40% is the male. The cause in 40% is the female and the cause in 20% is both. Often infertility in males is due to low sperm count.When males are inactive the temperature in the testes can be too high for proper sperm production. Overweight females have trouble conceiving because small follicles and ovulation fails. Pelvic inflammation can cause blockage of the oviducts. Medical intervention can sometimes help infertile couple conceive. Sometimes females can be given fertility drugs. These may cause multiple ovulations and even multiple births. There are also assisted reproductive technologies that increase the chance of pregnancy. A woman can be artificially inseminated by a donor. Sperm are placed in the
vagina by a physician. In males with low sperm counts their sperm can be collected over a time so that they can artificially inseminate their partners. Often a woman is artificially inseminated by a donor who is unknown to her. Sometimes the sperm are placed directly into the uterus. During in vitro fertilization immature eggs are collected from follicles. They will mature in glassware and concentrated sperm are added. Then the embryo(s) is transferred to the uterus. Sometimes women are contracted by infertile women to have a baby for her. The sperm and egg could be contributed by the contracting parents.
STDs are caused by viruses, bacteria, protists, fungi or animals. Some viral STDs are genital herpes and HIV/AIDS. AIDS is the last stage of an HIV infection. The primary host of HIV is a T lymphocyte. These are the cells that would normally trigger an immune response so the immune system is greatly impaired. In the early stage the symptoms are few but the individual is highly contagious. By the last stage the T lymphocyte count is very low and the person usually contracts a normally maintainable infection. The person will die from this opportunistic infection. Genital herpes is the herpes simplex virus type-2. Its symptoms include itching, blisters, fever, pain on urination, swollen groinal lymph nodes. These blisters will rupture and leave very painful ulcers. Pregnant women with herpes should have a C section because it prevents the possibility of the baby contracting the virus in the birth canal. Genital warts are another virus. They appear as lesions on the genitals. They are linked to cancer of the genitalia. Hepatitis is a virus that infects the liver. There are six different kinds. Four of these are sexually transmitted or can be.
Chlamydia (burning and discharge), gonorrhea (pain on urination and greenish discharge) and syphilis (chancre, rash, patches on the mucous membranes, possible gummas and aneurysms) are all bacterial STDs. Depending on the person these infections can be very mild to very severe.
II. Development and Aging
A. Fertilization
When a sperm and an egg unite they form a zygote. This is the first cell o
f a new individual. This process is called fertilization. The tail of a sperm is a flagellum, which allows it to swim toward the egg. The mitochondria necessary for energy are found in the middle section. The head is the nucleus and is the only part that will fuse with the egg nucleus. The plasma membrane of the egg is covered by the zona pellucida. The zona pellucida is surrounded by a few layers of follicular cells called the corona radiata. Several sperm will penetrate the corona radiata during fertilization and many will attempt to penetrate the zona pellucida. Only one will enter the egg. When a sperm touches the egg the membrane depolarizes and no other sperm can bind to the membrane.
A. The Life Cycle
B. Male Reproductive System
C.Female Reproductive System
D. Female Hormone Levels
E. Control of Reproduction
F. STDs
II. Development and Aging
A. Fertilization
B. Pre-embryonic/Embryonic Development
C. Fetal Development
D. Pregnancy and Birth
E. Development After Birth
A. The life cycle
Puberty is a sequence in which a person becomes sexually mature. Puberty is usually completed between 11 and 13 for girls and between 14 and 16 for boys. The reproductive system is the one system of the body that differs greatly between males and females. Male reproductive organs (testes) produce sperm. Female reproductive organs (ovaries) produce eggs
. In men the sperm are transported through the penis. Females transport the eggs to the uterus. The penis delivers sperm to the vagina through intercourse. The vagina will also be the birth canal. The uterus holds the developing fertilized egg. Both the testes and the ovaries produce sex hormones. The respective hormones give masculine or feminine qualities.Mitosis duplicates our 46 chromosomes before dividing. However, in meiosis, which only occurs in the testes and ovaries for reproduction, the diploid number of chromosomes is reduced to twenty three. This way when the sperm fertilizes the egg, the zygote (or new cell) has 46 chromosomes, instead of the number doubling each generation.
This zygote will one day be a full-
fledged human.
B. Male reproductive systemfledged human.
The testes are the main sex organ (gonads). They are paired and they found in the sacs of the scrotum. When sperm is produced it is stored for maturation in the epididymis. Once mature the sperm enters a vas deferens. They may be stored here for a time. The vas deferentia wrap around the bladder and empty into an ejaculatory duct. These empty into the urethra. Sperm leave the penis in semen during ejaculation. The semen carries secretions from the prostate, bulbourethral glands and the seminal vesicles. The seminal fluid contains nutrients, chemicals and sugars. All are important to sperm energy and transportation.
The penis is the organ of male intercourse. This consists of a shaft and a tip called the glans penis. Erectile tissue contains spaces for blood. This spongy tissue fills with blood when stimulated by NO (nitric oxide) and cGMP (cyclic guanosine monophosphate). The veins that take away the blood are compressed and the penis becomes erect. A sphincter closes off the bladder which keeps urine from entering the urethra. As stimulation increases seminal fluid enter the urethra and the glands inject secretions. Rhythmic muscle contractions push the seminal fluid out of the urethra. This is ejaculation. This is one aspect of the male orgasm (sensations, both physical and psychological that occur at the climax of sexual intercourse.) The penis becomes flaccid again after ejaculation or after loss of sexual arousal.
Testes descend into the scrotum from the abdominal cavity during puberty. This is important because the temperature of the abdominal cavity is too high to produce sperm. A testis is made up of compartments called lobules. Each contain one to three seminiferous tubules. Inside spermatogenesis (production of sperm) is occurring. The original sperm cell for spermatogenesis is the spermagonia. It divides into two primary spermocytes through mitosis. Te secondary spermocytes are the meiosis division of primary spermocytes. Each secondary spermocyte becomes two early spermatids. When these
mature they become sperm. The process is nourished and regulated by sertoli cells. The process takes about 74 days. The parts of a mature sperm are the head, the middle piece and the tail. The head contains a nucleus and enzymes needed to penetrate the egg. The tail acts as a flagellum.The hypothalamus is in control of hormone release and therefore testes' function. It secretes a hormone called gonadotropin-releasing hormone (GnRH.) This stimulates the petuitary gland to secrete the gonadotropic hormones FSH and LH. FSH promotes the production of sperm when found in males. LH controls testosterone production when found in males. Testosterone is essential for the development of the male reproductive organs. Testosterone also contributes to other distinctive characteristics of males (i.e. they tend to be taller, hairier and broader than females.)
This cross-section shows the male
reproductive system.
C. Female reproductive systemreproductive system.
The female gonads are the ovaries. They are also paired. They produce eggs. The oviducts, or fallopian tubes extend from the uterus to the ovaries. When an egg bursts from an ovary it is swept into the fallopian tube by its finger-like projections called fimbriae. The egg is then propelled by ciliary movement and muscle contraction to the uterus. An egg will generally live only 6-24 hours without being fertilized. Fertilization and zygote formation take place in the oviduct, normally. The developing embryo wil usually arrive at the uterus after several days. It will then embed in the uterine lining. The uterus is a muscular organ with thick walls. It is about the size and shape of a pear. The cervix, at the bottom of the uterus, joins almost a right angle. Development of the embryo and fetus takes place in the uterus. It starts at only about 5cm wide but can grow to 30cm for the development of a fetus.The endometrium, which lines the uterus, is essential to the formation of placenta, which nourishes the fetus. A small opening in the cervix leads to the vaginal canal. The vagina is a tube that is functional for intercourse (for fertilization) and as the birth canal. It also is the exit for menstrual flow.
The vulva is the term for the collective of external female genitalia. Two large, hair-covered fold of skin called the labia majora extend back from the mons pubis, a fatty area under the pubic hair. Two small folds lay just inside the labia majora called the labia minora. They extend from the vaginal opening to form a foreskin for the glans clitoris. The clitoris is contains erectile tissue that fills with blood when aroused. The cleft between the labia minora contains the urethra and the vaginal opening. The urinary and sexual systems, unlike in males, are separate.
The labia minora, vaginal wall and clitoris become engorged with blood during stimulation. The breasts also swell and the nipples become erect. The labia majora enlarge as well. The vagina is lubricated by glands that secrete mucus and fluid. The clitoris is what is actually stimulated in sexual intercourse and can swell to two to three times its normal size. Orgasms occur at the height of sexual response which causes the walls of the vagina and uterus to contract rhythmically. There is no refractory period for females after orgasms and can have many in one sexual experience.
D. Female hormone levels
An ovary has many follicles, each containing an immature egg called an oocyte. At puberty a female will have somewhere between 300,000-400,000 follicles. A very small number of these will ever mature. During the reproductive years a female will only produce one egg a month. The follicle goes through three different stages and then back, in what is called the ovarian cycle. The primary follicle (stage 1) contains epithelial cells that surround an oocyte. The secondary follicle (stage 2) surrounds the oocyte with follicular fluid and washes it. The vesicular follicle (stage 3) continues to fill with fluid until it balloons the ovary wall. When an oocyte goes through meiosis it reduces after the first stage into the secondary oocyte and the polar body, which simply holds the discarded chromosomes. If fertilize the 14th day of a 28 day cycle. If fertilization does not occur then a new cycle will begin with menstruation.
Estrogen is mainly responsible for secondary functions in women, such as fat distribution (curves and breasts) and, generally, less body hair than men. Progesterone is also involved in breast development and more hormones are also involved in milk production. Between the ages of 45 and 55 the ovarian cycle will, likely, cease. This is called menopause. The ovaries no longer produce estrogen or progesterone. Completion of menopause d the secondary oocyte will undergo meiosis 2. Before any of this occurs the oocyte is released from the ovary by bursting from the vesicular follicle. This is called ovulation. When the vesicular follicle has released the oocyte it becomes a corpus luteum which is a gland-like structure. If the egg is not fertilized the corpus luteum disinegrates. The ovary also produces the sex hormones. The corpus luteum will produce progesterone while the primary and secondary follicles produce estrogen. Like in males, females produce GnRH (hypothalamus), FSH ans LH (pituitary)The last two stimulate the ovarian cycle in females. Gonadotropic hormones occur intermittently throughout the cycle. Through the feedback process the hormone levels cause ovulation onis usually considered after a year with no menstruation period. The 28-day cycle, or uterine cycle, is marked by four definite stages. In the first the endometrium disintegrates and causes the blood vessels to rupture. Blood and tissue, called the menses, passes out of the vagina. This is known as menstruation. In the second stage the endometrium thickens with the increased production of estrogen. In the third, usually on day 14, ovulation occurs. The last period, increased production of progesterone causes the endometrium to double or triple in thickness. The endometrium is now ready to receive a developing embryo. If this does not happen, sex hormones will decrease and cause the endometrium to break down again.
During intercourse many dsperm will travel to
the oviduct where the egg is. Only one will fertilize the egg. If it becomes a zygote it will begin to develop on its way down the oviduct to the uterus. It will attach to the endometrium and implant. Pregnancy has now begun. The placenta sustains the embryo. This is where exchange occurs between maternal and fetal tissue. The placenta will initially produce the hormone HCG. Detection of it in the bloodstream or urine signifies pregnancy. Increased production of progesterone will signal the ceasing of follicle beginning. The endometrium does not break down resulting in no menstruation.See ovulation take place!
E. Control of reproductionBirth control methods are used to decrease the likelihood of reproduction. The most reliable method is abstinence, or the refrain from sexual intercourse. It is also the most reliable inhibitor of sexually transmitted diseases (STDs.) There are a number of birth control methods and many used are contraceptives. These are devices or medications that inhibit pregnancy. Some are male and female condoms, birth control pills, implants (usually contain hormones), and many others.
Infertility is the inability to become pregnant after a year of intercourse. About 15% of all couple are infertile. The cause in 40% is the male. The cause in 40% is the female and the cause in 20% is both. Often infertility in males is due to low sperm count.When males are inactive the temperature in the testes can be too high for proper sperm production. Overweight females have trouble conceiving because small follicles and ovulation fails. Pelvic inflammation can cause blockage of the oviducts. Medical intervention can sometimes help infertile couple conceive. Sometimes females can be given fertility drugs. These may cause multiple ovulations and even multiple births. There are also assisted reproductive technologies that increase the chance of pregnancy. A woman can be artificially inseminated by a donor. Sperm are placed in the
vagina by a physician. In males with low sperm counts their sperm can be collected over a time so that they can artificially inseminate their partners. Often a woman is artificially inseminated by a donor who is unknown to her. Sometimes the sperm are placed directly into the uterus. During in vitro fertilization immature eggs are collected from follicles. They will mature in glassware and concentrated sperm are added. Then the embryo(s) is transferred to the uterus. Sometimes women are contracted by infertile women to have a baby for her. The sperm and egg could be contributed by the contracting parents.The process of in vitro fertilization
F. STDsSTDs are caused by viruses, bacteria, protists, fungi or animals. Some viral STDs are genital herpes and HIV/AIDS. AIDS is the last stage of an HIV infection. The primary host of HIV is a T lymphocyte. These are the cells that would normally trigger an immune response so the immune system is greatly impaired. In the early stage the symptoms are few but the individual is highly contagious. By the last stage the T lymphocyte count is very low and the person usually contracts a normally maintainable infection. The person will die from this opportunistic infection. Genital herpes is the herpes simplex virus type-2. Its symptoms include itching, blisters, fever, pain on urination, swollen groinal lymph nodes. These blisters will rupture and leave very painful ulcers. Pregnant women with herpes should have a C section because it prevents the possibility of the baby contracting the virus in the birth canal. Genital warts are another virus. They appear as lesions on the genitals. They are linked to cancer of the genitalia. Hepatitis is a virus that infects the liver. There are six different kinds. Four of these are sexually transmitted or can be.
Chlamydia (burning and discharge), gonorrhea (pain on urination and greenish discharge) and syphilis (chancre, rash, patches on the mucous membranes, possible gummas and aneurysms) are all bacterial STDs. Depending on the person these infections can be very mild to very severe.
II. Development and Aging
A. Fertilization
When a sperm and an egg unite they form a zygote. This is the first cell o
f a new individual. This process is called fertilization. The tail of a sperm is a flagellum, which allows it to swim toward the egg. The mitochondria necessary for energy are found in the middle section. The head is the nucleus and is the only part that will fuse with the egg nucleus. The plasma membrane of the egg is covered by the zona pellucida. The zona pellucida is surrounded by a few layers of follicular cells called the corona radiata. Several sperm will penetrate the corona radiata during fertilization and many will attempt to penetrate the zona pellucida. Only one will enter the egg. When a sperm touches the egg the membrane depolarizes and no other sperm can bind to the membrane.Many sperm attempt, but only one
will enter the egg.
will enter the egg.
B. Pre-embryonic/ embryonic development
The processes of human development are: cleavage (early cell dvision), growth ( the daughter cells begin increasing in size), morphogenesis (certain cells move to certain areas and shaping occurs) and differentiation (cells take on specific structures and functions.)
The first week after fertilization is pre-embryonic. The zygote divides repeatedly immediately after fertilization. It travels during the oviduct while doing so. The embryonic cells become a blastocyst which is separated by the inner and outer cell mass. The inner will become the embryo. If the inner mass splits in two than identical twins can develop. From the second week to the end of the second month embryonic development occurs. The embryo will have just implanted into the uterus wall.The outer cells which became the chorion will secrete enzymes to digest some of the endometrium. It also secretes the HCG hormone. Th
e inner cell mass becomes the embryonic disk throughout the second week. Two other membranes form: the yolk sac and the amniotic cavity. Its fluid insulates and absorbs shock. Gastrulation is the process where the embryonic disk separates into three layers of tissue. The first, ectoderm, will become the skin epithelial linin and the nervous system. The second, mesoderm, will become the skeleton, muscles, dermis of skin, cardiovascular system, reproductive system and urinary system. The third, endoderm, will become epithelial lining. After the third week the nervous system is visible. The heart begins to form. It will pump blood by the end of the fourth week. The body stalk that is evident in the fourth will be the umbilical cord by the end of the fifth week. Limb buds appear that will later be arms and legs. From the sixth to eighth week the embryo becomes shaped more like a human being. Even though all organ systems have been developed the embryo weighs no more than an aspirin.
The umbilical cord is the lifeline of the fetus. Its arteries carry O2 poor blood to the placenta and its veins bring nutrients and O2 rich blood to the heart of the fetus.
The processes of human development are: cleavage (early cell dvision), growth ( the daughter cells begin increasing in size), morphogenesis (certain cells move to certain areas and shaping occurs) and differentiation (cells take on specific structures and functions.)
The first week after fertilization is pre-embryonic. The zygote divides repeatedly immediately after fertilization. It travels during the oviduct while doing so. The embryonic cells become a blastocyst which is separated by the inner and outer cell mass. The inner will become the embryo. If the inner mass splits in two than identical twins can develop. From the second week to the end of the second month embryonic development occurs. The embryo will have just implanted into the uterus wall.The outer cells which became the chorion will secrete enzymes to digest some of the endometrium. It also secretes the HCG hormone. Th
e inner cell mass becomes the embryonic disk throughout the second week. Two other membranes form: the yolk sac and the amniotic cavity. Its fluid insulates and absorbs shock. Gastrulation is the process where the embryonic disk separates into three layers of tissue. The first, ectoderm, will become the skin epithelial linin and the nervous system. The second, mesoderm, will become the skeleton, muscles, dermis of skin, cardiovascular system, reproductive system and urinary system. The third, endoderm, will become epithelial lining. After the third week the nervous system is visible. The heart begins to form. It will pump blood by the end of the fourth week. The body stalk that is evident in the fourth will be the umbilical cord by the end of the fifth week. Limb buds appear that will later be arms and legs. From the sixth to eighth week the embryo becomes shaped more like a human being. Even though all organ systems have been developed the embryo weighs no more than an aspirin.At three weeks this embryo has eyes and limb buds.
C. Fetal DevelopmentThe umbilical cord is the lifeline of the fetus. Its arteries carry O2 poor blood to the placenta and its veins bring nutrients and O2 rich blood to the heart of the fetus.
Between the the third and fourth months the eyes and ears are apparent. The head growth begins to slow and the rest of the increases in size. Skeleton forms as bones replace cartilage. Gender can be determined and fingernail, nipples, eyelashes and eyebrows are apparent. The heart beat can be heard at the end of the fourth month. Between the fifth and seventh months movement can be felt. The skin is coated with a protective substance, vernix caseosa. The fetus weighs about 3 pounds and is about a foot long at the end of this period. The baby could possibly survive if born at this time. Throughout the next two months the fetus continues to grow until it reaches about 7.5 pounds and is almost two feet long. Near the end of the nine months the fetus will rotate so the head is pointed toward the cervix. It is possible that it won't turn and breech birth, which is difficult and dangerous, is possible. Most likely a cesarean section would be performed to save the baby from asphyxiation. The sex of an individual is determined at fertilization. The gonads don't form, however until about the seventh week. The sex organs form according to hormone action. Some individuals with the XY (m
ale) chromosome may become female because the Y chromosome is missing a piece. This missing piece may be present in some with XX (female) chromosomes. This causes them to have male genitalia. Those with Ambiguous Sex Determination develop as females even though they will have testes internally. This is because the plasma membrane receptors for testosterone are ineffective. About 1% of the population may have Psuedohermaphroditism. This is where an individual has testes, but appears female until puberty. At puberty male aspects become apparent as the body responds to testosterone. The clitoris will enlarge and look like a penis.
Breech birth may cause the child
to asphyxiate.
ale) chromosome may become female because the Y chromosome is missing a piece. This missing piece may be present in some with XX (female) chromosomes. This causes them to have male genitalia. Those with Ambiguous Sex Determination develop as females even though they will have testes internally. This is because the plasma membrane receptors for testosterone are ineffective. About 1% of the population may have Psuedohermaphroditism. This is where an individual has testes, but appears female until puberty. At puberty male aspects become apparent as the body responds to testosterone. The clitoris will enlarge and look like a penis.Breech birth may cause the child
to asphyxiate.
D. Pregnancy and Birth
Many changes take place in the woman's body during pregnancy. When first pregnant the woman may be nauseous and vomit. After this there might be an increase of energy. The woman will gain weight for many reasons: the breasts and uterus enlarge, There is the amniotic fluid as well as the storage of protein and fat. The woman may have lower blood pressure and retain water and sodium more. Then blood volume can increase 40%. Many will experience heartburn because smooth muscle relaxes much more. This may also cause constipation. Respiratory functions improve as the bronchial tubes relax and the uterus increases in size. The size increase causes the thoracic cavity to expand. The CO2 level drops about 20% which sends better blood to the fetus. Stress incontinence can be caused due to compression of the ureters and bladder.
Contractions happen throughout pregnancy.They are light at first but become stronger and more frequent at the end of pregnancy. Before parturition, or birth, the mucous plug will be expelled. During the first stage of birth the contractions occur so that the cervical canal disappears. Then the baby's head will open the cervix more so. The amniotic sac will rupture by this point if it had not already. In the second stage the contractions occur every 1-2 minutes and last about a minute each. The desire to push becomes greater as the baby's head enters the vagina. The baby descends head first. Then each shoulder comes. The rest follows easily. Then the umbilical cord is cut. The third stage is the after birth. The placenta is delivered. The contractions dislodge it as the uterus shrinks.
E. Development after birth
Development occurs throughout life and can be marked by four stages: infancy, childhood, adolescence and adulthood. Gerontology is the study of aging. This is of interest because there are more older people now than ever before. The human lifespan is expected to jump to 120 years maximum. There are three major hypotheses about the cause of aging. One is the genetic origin. Some genes may express the decrease of life span. Mitochondria can perhaps produce free radicals that will render cells dysfunctional. Another idea is that the decrease in hormonal activity affects the organs and immune system. It may not be the whole system that stops functioning but that a vital tissue decreases or changes. It is also possible that much of the aging process today is do to diet and exercise as well as other health habits.
There are many effects on the body as aging occurs. skin becomes thinner and less elastic.Sagging and wrinkling occur and the people feel colder as there is less adipose in the epithelial system. The skin dries since there is less oil glands. The arteries become more rigid and less effective. There is less elasticity in the lungs and breathing becomes more difficult. Blood flow to the liver and kidneys is reduced and they are less efficient. The digestive tract becomes less efficient. Short term memory may go. However, cognitive skill can remain unchanged without complications. hearing is more difficult as the ability to hear higher pitches goes. Glaucoma may develop as fluid builds up in the eye. Bone density is lost. Sometimes weight gain occurs because metabolism slows. The external genitals of females become less pronounced. The walls of the oviducts and vagina become thinner. Some sperm production occurs to death, but the number of sperm produced decreases gradually between 50 and 90 years of age. Though all these effects have been seen, they may be due to the health habits of the older generation. We won't know until we see the next generation come of age.
Many changes take place in the woman's body during pregnancy. When first pregnant the woman may be nauseous and vomit. After this there might be an increase of energy. The woman will gain weight for many reasons: the breasts and uterus enlarge, There is the amniotic fluid as well as the storage of protein and fat. The woman may have lower blood pressure and retain water and sodium more. Then blood volume can increase 40%. Many will experience heartburn because smooth muscle relaxes much more. This may also cause constipation. Respiratory functions improve as the bronchial tubes relax and the uterus increases in size. The size increase causes the thoracic cavity to expand. The CO2 level drops about 20% which sends better blood to the fetus. Stress incontinence can be caused due to compression of the ureters and bladder.
Contractions happen throughout pregnancy.They are light at first but become stronger and more frequent at the end of pregnancy. Before parturition, or birth, the mucous plug will be expelled. During the first stage of birth the contractions occur so that the cervical canal disappears. Then the baby's head will open the cervix more so. The amniotic sac will rupture by this point if it had not already. In the second stage the contractions occur every 1-2 minutes and last about a minute each. The desire to push becomes greater as the baby's head enters the vagina. The baby descends head first. Then each shoulder comes. The rest follows easily. Then the umbilical cord is cut. The third stage is the after birth. The placenta is delivered. The contractions dislodge it as the uterus shrinks.
E. Development after birth
Development occurs throughout life and can be marked by four stages: infancy, childhood, adolescence and adulthood. Gerontology is the study of aging. This is of interest because there are more older people now than ever before. The human lifespan is expected to jump to 120 years maximum. There are three major hypotheses about the cause of aging. One is the genetic origin. Some genes may express the decrease of life span. Mitochondria can perhaps produce free radicals that will render cells dysfunctional. Another idea is that the decrease in hormonal activity affects the organs and immune system. It may not be the whole system that stops functioning but that a vital tissue decreases or changes. It is also possible that much of the aging process today is do to diet and exercise as well as other health habits.
There are many effects on the body as aging occurs. skin becomes thinner and less elastic.Sagging and wrinkling occur and the people feel colder as there is less adipose in the epithelial system. The skin dries since there is less oil glands. The arteries become more rigid and less effective. There is less elasticity in the lungs and breathing becomes more difficult. Blood flow to the liver and kidneys is reduced and they are less efficient. The digestive tract becomes less efficient. Short term memory may go. However, cognitive skill can remain unchanged without complications. hearing is more difficult as the ability to hear higher pitches goes. Glaucoma may develop as fluid builds up in the eye. Bone density is lost. Sometimes weight gain occurs because metabolism slows. The external genitals of females become less pronounced. The walls of the oviducts and vagina become thinner. Some sperm production occurs to death, but the number of sperm produced decreases gradually between 50 and 90 years of age. Though all these effects have been seen, they may be due to the health habits of the older generation. We won't know until we see the next generation come of age.
Sunday, April 27, 2008
Reproduction Lab
There are many stages to the fetal development. Some are minute and some are monumental, depending on how one sees things. Even so, it is an ongoing process and changes are not sudden. There are landmarks that can tell you what and when certain developments happen. Here are some that I find very interesting.
1. At 4 weeks the embryo is just two layers of cells, the epiblast and the hypoblast.
2. A lot happens in just the "first month" (beginning at about 4 weeks after conception) by week six, just two weeks after the embryo was but two layers of cells, the embryo is forming vocal chords and a tongue. It already has fingers and will begin to move its arms and legs in this week. The heart is apparent by this time, too.
3. At 8 weeks the brain has begun to connect nerve paths to other parts of the body. The baby has knee joints and definitive, flexed wrists. The baby also has formed eyelids that virtually cover the eyes.
4. By 11 weeks the baby has developed bones. This week the bones will have begun to harden. Teeth buds will also have formed beneath the gums.
5. By 13 weeks the baby will have a unique set of fingerprints. It will also have the abilityto urinate, as it begins to expel amniotic fluid it has swallowed.
6. By 16 weeks the circulatory system is developed and the baby's heart is busy pumping.
7. By 18 weeks the baby has begun to move about regularly.
8. At 24 weeks the baby started to develop taste buds and what would life be like without those? Also thelungs have developed more and the bronchial tree is noticeable.
9. Because a baby's lungs are fully developed at this point, baby's born at 34 weeks have a 99% survival rate!
10. In the 40th and 41st weeks the baby is as developed as it will be before birth. It is ready to make the trip into the outside world. Its skull plates have separated to make it easier for the head to go through the birth canal.
1. At 4 weeks the embryo is just two layers of cells, the epiblast and the hypoblast.
2. A lot happens in just the "first month" (beginning at about 4 weeks after conception) by week six, just two weeks after the embryo was but two layers of cells, the embryo is forming vocal chords and a tongue. It already has fingers and will begin to move its arms and legs in this week. The heart is apparent by this time, too.
3. At 8 weeks the brain has begun to connect nerve paths to other parts of the body. The baby has knee joints and definitive, flexed wrists. The baby also has formed eyelids that virtually cover the eyes.
4. By 11 weeks the baby has developed bones. This week the bones will have begun to harden. Teeth buds will also have formed beneath the gums.
5. By 13 weeks the baby will have a unique set of fingerprints. It will also have the abilityto urinate, as it begins to expel amniotic fluid it has swallowed.
6. By 16 weeks the circulatory system is developed and the baby's heart is busy pumping.
7. By 18 weeks the baby has begun to move about regularly.
8. At 24 weeks the baby started to develop taste buds and what would life be like without those? Also thelungs have developed more and the bronchial tree is noticeable.
9. Because a baby's lungs are fully developed at this point, baby's born at 34 weeks have a 99% survival rate!
10. In the 40th and 41st weeks the baby is as developed as it will be before birth. It is ready to make the trip into the outside world. Its skull plates have separated to make it easier for the head to go through the birth canal.
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