Phosphorous Cycle
Nitrogen Cycle
Greenhouse Effect
The Water Cycle
Grazing and Detrital Food Webs
Terrestrial Biomes
Friday, July 18, 2008
Compendium Review Chapter 23- Pictures
Phosphorous Cycle
Nitrogen Cycle
Greenhouse Effect
The Water Cycle
Grazing and Detrital Food Webs
Terrestrial Biomes
Compendium Review Chapter 23
I. The Nature of Ecosystems
II. Energy Flow
III. Global Biogeochemcial Cycles
I. The Nature of Ecosystems
A. Biosphere: Where organisms are found on planet Earth, from the atmosphere above to the depths of the oceans below, and everything in between.
B. Entire Biosphere is one giant Ecosystem: A place where organisms interact among themselves and with the physical and chemical environment.
- These interactions help maintain both the ecosystem and the biosphere.
- Human interactions can alter interactions between organisms and their environments in ways that reduce the abundance and diversity of life within the ecosystem.
C. Ecosystems: Many different types of terrestial ecosystems, also called biomes.
- Biomes: Temperature and rainfall define the biomes, whose organisms are adapted to the regional climate.
- Examples: Tropical rain forest, savanna, temperate grasslands, temperate forests, deserts, taiga, and tundra.
(Insert Terrestrial Biomes picture / ecology.botany.ufl.edu / http://ecology.botany.ufl.edu/ecologyf02/biodiv.html )
- Aquatic ecosystems: Divided by whether they are freshwater or salt water.
D. Biotic Components of an Ecosystem:
1d. Abiotic components: nonliving.
2d. Biotic components: living things categorized according to the food source.
- Autotrophs: Require only inorganic nutrients and an outside energy source to produce organic nutrients for their own use and for the other members of a community. They are called producers. (ie algae, photosynthetic organisms.)
- Heterotrophs: Need a source of organic nutrients. They are consumers.
* Herbivores: Animals that eat plants or algae. (ie insects, protists.)
* Carnivores: Feed on other animals. (ie birds that feed on insects, hawks feed on birds, etc.)
* Omnivores: Feed on both. (ie humans.)
* Detritus Feeders: Organisms that feed on detritus, which is decomposing particles of organic matter. (ie Earthworms, beetles, etc.)
E. Niche: Role of an organism in an ecosystem: how it eats its food and what eats it, and how it interacts with other populations in the same community.
F. Chemical Flow and Chemical Cycling
1f. Every ecosystem is characterized by two phenomena: energy flow and chemical cycling.
- Energy flow: Begins when producers absorb solar energy.
- Chemical Cycling: Begins when producers take in inorganic nutrients from the physical environment.
- Next, through photosynthesis, producers make organic nutrients directly for themselves and indirectly for the other populations of the ecosystem.
* Energy Flow: As nutrients pass from one population to another, all energy content is converted to heat, which dissipates in the environment.
- Most ecosystems require a constant supply of solar energy.
* Chemicals cycle when inorganic nutrients are returned to the producers from the atmosphere or soil. (Mader 493-495)
II. Energy Flow
A. Various interconnecting paths of energy flow are represented by a food web, which is a diagram that describes trophic (feeding) relationships.
- Two examples: Grazing Web- Begins with an oak tree and grass. Detrital Web- Begins with detritus and the decomposers found within detritus.
(Insert Grazing and Detritus Food Webs picture / project.bio.iastate.edu / http://project.bio.iastate.edu/Courses/biol123/lectures/Lecture06-Ecosystems/slide10.htm)
B. Trophic Levels:
1b. Food Chains: Diagrams that show a single path of energy flow. Ex. In grazing food chain, you would have leaves, followed by caterpillars, followed by birds, followed by hawks. In detrital food chain, you would have detritus, followed by earthworms, followed by shrews.
2b. Trophic level: Composed of all the organisms that feed at a particular link in a food chain. Example: In grazing food web, trees are producers (first trophic level), first series of animals are primary consumers (second trophic level), and the next group of animals are secondary consumers (third trophic level).
C. Ecological Pyramids: The flow of energy with large losses between successive trophic levels.
- Only about 10% of the energy of one trophic level is available to the next tropic level.
1c. Biomass: The number of organisms multiplied by the weight of organic matter within one organism. (Mader 497-498)
III. Global Biogeochemical Cycles
A. All organisms require a variety of organic and / or inorganic nutrients.
1a. Biogeochemical Cycles: Pathways by which chemicals circulate through ecosystems involve both living (biotic) and nonliving (geological) components.
- Gaseous: Element returns to and is withdrawn from the atmosphere as a gas. (ie carbon and nitrogen cycles.)
- Sedimentary: The chemical is absorbed from the soil by plant roots, passed to heterotrophs, and returned to soil by decomposers. (ie phosphorus cycle.)
2a. Chemical Cycling involves a reservoir, an exchange pool, and a biotic community.
- Human activities remove chemicals from reservoirs and exchange pools, and make them available to the biotic community. Can result in pollution, because it upsets the normal balance of nutrients for producers in the environment.
B. The Water Cycle:
1b. Evaporation, precipitation, runoff, etc. See picture. All water is eventually returned to the sea. Aquifer: Rock layers that contain water and release it.
(Insert Water Cycle picture / Frolich PowerPoint Slide 18)
2b. Human Activities:
-Humans interfere w/ water cycle in three ways: First, they take water from aquifers. Second, They clear vegetation from land and build roads and buildings that prevent percolation and increase runoff. Third, they interfere with the natural processes that purify water and instead add pollutants like sewage and chemicals to water.
C. The Carbon Cycle:
1c. Carbon dioxide in atmosphere is the exchange pool for the carbon cycle.
- In this cycle, organisms in both terrestrial and aquatic ecosystems exchange carbon dioxide with the atmosphere. ie. Plants take co2 from air, and through photosynthesis, incorporate carbon into nutrients that are used by autotrophs and heterotrophs. When organisms respire, carbon is returned to the atmosphere as co2. In aquatic, it is indirect: co2 from air combines with h2o to produce bicarbonate ion, a source of carbon for algae that makes food for themselves and for heterotrophs. When aquatic organisms respire, the co2 they give off becomes bicarbonate ion.
2c. Living and dead organisms contain organic carbon and serve as one of the reservoirs for the carbon cycle. Decomposition returns co2 to the atmosphere.
3c. Fossil Fuels: When plant and animal remains are transformed into coal, oil, and natural gas.
4c. Human Activities:
- More co2 is being deposited in the atmosphere than is being removed. Largely due to burning of fossil fuels and destruction of forest. When a forest is destroyed, we reduce a reservoir and the very organisms that take up excess co2.
5c. Global Warming: Human activities emit co2 and other gases, like nitrous oxide into the atmosphere. These gases are known as greenhouse gases, because they allow solar radiation to pass through but hinder the escape of infrared rays back into space.
- Contribute to rise in Earth's ambient temperature, = global warming.
- Higher temperature = greater evaporation of h2o, forming more clouds, and setting up a positive feedback effect that will increase global warming even more.
- Other effects: Temps in polar regions rise, glaciers will melt, sea levels will rise, h2o evap. will increase, = increased rainfall along coasts and dryer conditions inland. Droughts reduce agricultural yields, trees will die, etc. Coastal cities could sink! (Mader 498-499)
(Insert Greenhouse Effect picture / Frolich PowerPoint Slide 21)
D. The Nitrogen Cycle: Nitrogen gas accounts for approx. 78% of the atmosphere.
1d. Ammonium Formation and Use:
- Nitrogen fixation occurs when nitrogen gas is converted to ammonium, a form plants can use.
2d. Nitrate Formation and Use:
- Plants can use nitrates as a source of nitrogen.
- Nitrification: Production of nitrates during the nitrogen cycle. Can occur when cosmic radiation, meteor trails, and lightning provide high energy needed for nitrogen to react with oxygen. Or, when ammonium in the soil is converted to nitrate by soil bacteria, or when nitrate-producing bacteria converts nitrite to nitrate.
- Assimilation: Plants take up ammonia and nitrate from the sol and use these ions to produce proteins and nucleic acids.
(Insert Nitrogen Cycle picture / www.stormfront.org / http://www.stormfront.org/forum/showthread.php?t=325972)
3d. Formation of Nitrogen Gas from Nitrate:
- Denitrification: The conversion of nitrate back to nitrogen gas, which enters the atmosphere. Counterbalances nitrogen fixatin except for human activities.
4d. Human Activities: Significantly alter the transfer rates in the nitrogen cycle by producing fertilizers from nitrogen- nearly doubles the fixation rate. Runs off into water, creates overgrowth of algae, causes over-enrichment, and when algae die off, increased decomposer populations use up all oxygen in water, and results in massive fish kill.
1e. Acid Deposition: Nitrogen oxides and sulfur dioxide enter atmosphere from burning of fossil fuels. These gases combine with water vapor to form acids that return to the earth, and their deposit affects forest and lakes.
- Creation of smog, and trapped pollutants.
E. The Phosphorus Cycle: Phosphorous trapped in oceanic sediments moves onto land after a geological upheaval. Weathering of rocks places phosphate ions into soil. Some of this phosphate is used by plants in a variety of molecules, and the nucleotides that become a part of DNA and RNA. Animals eat producers and incorporate some of the phosphate into teeth, bones, and shells, which take many years to decompose.
(Insert Phosphorous Cycle picture / www.biologycorner.com / http://www.biologycorner.com/bio4/notes/chap45.html )
1e. Phosphorus and Water Pollution:
- Cultural Eutrophication: Overenrichment of waterways due to humans use of phosphate for fertilizer, animal wastes from livestock feedlots, and discharge from sewage treatment plants.
- Biological Magnification: Occurs as materials pass along a food chain and become more and more concentrated because they remain in body and are not excreted.
- Pollutants: Waste dumping, offshore mining and shipping, oil spills, etc.
- Many species are at the brink of extinction. (Mader 500-505)
II. Energy Flow
III. Global Biogeochemcial Cycles
I. The Nature of Ecosystems
A. Biosphere: Where organisms are found on planet Earth, from the atmosphere above to the depths of the oceans below, and everything in between.
B. Entire Biosphere is one giant Ecosystem: A place where organisms interact among themselves and with the physical and chemical environment.
- These interactions help maintain both the ecosystem and the biosphere.
- Human interactions can alter interactions between organisms and their environments in ways that reduce the abundance and diversity of life within the ecosystem.
C. Ecosystems: Many different types of terrestial ecosystems, also called biomes.
- Biomes: Temperature and rainfall define the biomes, whose organisms are adapted to the regional climate.
- Examples: Tropical rain forest, savanna, temperate grasslands, temperate forests, deserts, taiga, and tundra.
(Insert Terrestrial Biomes picture / ecology.botany.ufl.edu / http://ecology.botany.ufl.edu/ecologyf02/biodiv.html )
- Aquatic ecosystems: Divided by whether they are freshwater or salt water.
D. Biotic Components of an Ecosystem:
1d. Abiotic components: nonliving.
2d. Biotic components: living things categorized according to the food source.
- Autotrophs: Require only inorganic nutrients and an outside energy source to produce organic nutrients for their own use and for the other members of a community. They are called producers. (ie algae, photosynthetic organisms.)
- Heterotrophs: Need a source of organic nutrients. They are consumers.
* Herbivores: Animals that eat plants or algae. (ie insects, protists.)
* Carnivores: Feed on other animals. (ie birds that feed on insects, hawks feed on birds, etc.)
* Omnivores: Feed on both. (ie humans.)
* Detritus Feeders: Organisms that feed on detritus, which is decomposing particles of organic matter. (ie Earthworms, beetles, etc.)
E. Niche: Role of an organism in an ecosystem: how it eats its food and what eats it, and how it interacts with other populations in the same community.
F. Chemical Flow and Chemical Cycling
1f. Every ecosystem is characterized by two phenomena: energy flow and chemical cycling.
- Energy flow: Begins when producers absorb solar energy.
- Chemical Cycling: Begins when producers take in inorganic nutrients from the physical environment.
- Next, through photosynthesis, producers make organic nutrients directly for themselves and indirectly for the other populations of the ecosystem.
* Energy Flow: As nutrients pass from one population to another, all energy content is converted to heat, which dissipates in the environment.
- Most ecosystems require a constant supply of solar energy.
* Chemicals cycle when inorganic nutrients are returned to the producers from the atmosphere or soil. (Mader 493-495)
II. Energy Flow
A. Various interconnecting paths of energy flow are represented by a food web, which is a diagram that describes trophic (feeding) relationships.
- Two examples: Grazing Web- Begins with an oak tree and grass. Detrital Web- Begins with detritus and the decomposers found within detritus.
(Insert Grazing and Detritus Food Webs picture / project.bio.iastate.edu / http://project.bio.iastate.edu/Courses/biol123/lectures/Lecture06-Ecosystems/slide10.htm)
B. Trophic Levels:
1b. Food Chains: Diagrams that show a single path of energy flow. Ex. In grazing food chain, you would have leaves, followed by caterpillars, followed by birds, followed by hawks. In detrital food chain, you would have detritus, followed by earthworms, followed by shrews.
2b. Trophic level: Composed of all the organisms that feed at a particular link in a food chain. Example: In grazing food web, trees are producers (first trophic level), first series of animals are primary consumers (second trophic level), and the next group of animals are secondary consumers (third trophic level).
C. Ecological Pyramids: The flow of energy with large losses between successive trophic levels.
- Only about 10% of the energy of one trophic level is available to the next tropic level.
1c. Biomass: The number of organisms multiplied by the weight of organic matter within one organism. (Mader 497-498)
III. Global Biogeochemical Cycles
A. All organisms require a variety of organic and / or inorganic nutrients.
1a. Biogeochemical Cycles: Pathways by which chemicals circulate through ecosystems involve both living (biotic) and nonliving (geological) components.
- Gaseous: Element returns to and is withdrawn from the atmosphere as a gas. (ie carbon and nitrogen cycles.)
- Sedimentary: The chemical is absorbed from the soil by plant roots, passed to heterotrophs, and returned to soil by decomposers. (ie phosphorus cycle.)
2a. Chemical Cycling involves a reservoir, an exchange pool, and a biotic community.
- Human activities remove chemicals from reservoirs and exchange pools, and make them available to the biotic community. Can result in pollution, because it upsets the normal balance of nutrients for producers in the environment.
B. The Water Cycle:
1b. Evaporation, precipitation, runoff, etc. See picture. All water is eventually returned to the sea. Aquifer: Rock layers that contain water and release it.
(Insert Water Cycle picture / Frolich PowerPoint Slide 18)
2b. Human Activities:
-Humans interfere w/ water cycle in three ways: First, they take water from aquifers. Second, They clear vegetation from land and build roads and buildings that prevent percolation and increase runoff. Third, they interfere with the natural processes that purify water and instead add pollutants like sewage and chemicals to water.
C. The Carbon Cycle:
1c. Carbon dioxide in atmosphere is the exchange pool for the carbon cycle.
- In this cycle, organisms in both terrestrial and aquatic ecosystems exchange carbon dioxide with the atmosphere. ie. Plants take co2 from air, and through photosynthesis, incorporate carbon into nutrients that are used by autotrophs and heterotrophs. When organisms respire, carbon is returned to the atmosphere as co2. In aquatic, it is indirect: co2 from air combines with h2o to produce bicarbonate ion, a source of carbon for algae that makes food for themselves and for heterotrophs. When aquatic organisms respire, the co2 they give off becomes bicarbonate ion.
2c. Living and dead organisms contain organic carbon and serve as one of the reservoirs for the carbon cycle. Decomposition returns co2 to the atmosphere.
3c. Fossil Fuels: When plant and animal remains are transformed into coal, oil, and natural gas.
4c. Human Activities:
- More co2 is being deposited in the atmosphere than is being removed. Largely due to burning of fossil fuels and destruction of forest. When a forest is destroyed, we reduce a reservoir and the very organisms that take up excess co2.
5c. Global Warming: Human activities emit co2 and other gases, like nitrous oxide into the atmosphere. These gases are known as greenhouse gases, because they allow solar radiation to pass through but hinder the escape of infrared rays back into space.
- Contribute to rise in Earth's ambient temperature, = global warming.
- Higher temperature = greater evaporation of h2o, forming more clouds, and setting up a positive feedback effect that will increase global warming even more.
- Other effects: Temps in polar regions rise, glaciers will melt, sea levels will rise, h2o evap. will increase, = increased rainfall along coasts and dryer conditions inland. Droughts reduce agricultural yields, trees will die, etc. Coastal cities could sink! (Mader 498-499)
(Insert Greenhouse Effect picture / Frolich PowerPoint Slide 21)
D. The Nitrogen Cycle: Nitrogen gas accounts for approx. 78% of the atmosphere.
1d. Ammonium Formation and Use:
- Nitrogen fixation occurs when nitrogen gas is converted to ammonium, a form plants can use.
2d. Nitrate Formation and Use:
- Plants can use nitrates as a source of nitrogen.
- Nitrification: Production of nitrates during the nitrogen cycle. Can occur when cosmic radiation, meteor trails, and lightning provide high energy needed for nitrogen to react with oxygen. Or, when ammonium in the soil is converted to nitrate by soil bacteria, or when nitrate-producing bacteria converts nitrite to nitrate.
- Assimilation: Plants take up ammonia and nitrate from the sol and use these ions to produce proteins and nucleic acids.
(Insert Nitrogen Cycle picture / www.stormfront.org / http://www.stormfront.org/forum/showthread.php?t=325972)
3d. Formation of Nitrogen Gas from Nitrate:
- Denitrification: The conversion of nitrate back to nitrogen gas, which enters the atmosphere. Counterbalances nitrogen fixatin except for human activities.
4d. Human Activities: Significantly alter the transfer rates in the nitrogen cycle by producing fertilizers from nitrogen- nearly doubles the fixation rate. Runs off into water, creates overgrowth of algae, causes over-enrichment, and when algae die off, increased decomposer populations use up all oxygen in water, and results in massive fish kill.
1e. Acid Deposition: Nitrogen oxides and sulfur dioxide enter atmosphere from burning of fossil fuels. These gases combine with water vapor to form acids that return to the earth, and their deposit affects forest and lakes.
- Creation of smog, and trapped pollutants.
E. The Phosphorus Cycle: Phosphorous trapped in oceanic sediments moves onto land after a geological upheaval. Weathering of rocks places phosphate ions into soil. Some of this phosphate is used by plants in a variety of molecules, and the nucleotides that become a part of DNA and RNA. Animals eat producers and incorporate some of the phosphate into teeth, bones, and shells, which take many years to decompose.
(Insert Phosphorous Cycle picture / www.biologycorner.com / http://www.biologycorner.com/bio4/notes/chap45.html )
1e. Phosphorus and Water Pollution:
- Cultural Eutrophication: Overenrichment of waterways due to humans use of phosphate for fertilizer, animal wastes from livestock feedlots, and discharge from sewage treatment plants.
- Biological Magnification: Occurs as materials pass along a food chain and become more and more concentrated because they remain in body and are not excreted.
- Pollutants: Waste dumping, offshore mining and shipping, oil spills, etc.
- Many species are at the brink of extinction. (Mader 500-505)
Compendium Review Chapter 22- Pictures
Cro-Magnon Skull
Neanderthal and Modern Human Skull Comparison
Homo erectus
Homo habilis
Evolution of Primates
Human / Chimpanzee Skeletons 2
Human / Chimpanzee Skeletons 1
Evidence for Historical Fact of Evolution
Ambulocetus: Believes to have given rise to whales.
Charles Darwin
Early Earth
Stanley Miller Experiment
Stanley Miller
History of Life on Earth Chart
Compendium Review Chapter 22
I. Origin of Life
II. Biological Evolution
III. Classification of Humans
IV. Evolution of Hominids
V. Evolution of Humans
I. Origin of Life
A. Fundamental Principle of Biology: All living things are made of cells and every cell comes from a preexisting cell.
1a. Chemical Evolution: A slow increase in the complexity of chemicals. (Mader 468)
B. To understand evolution, we must appreciate deep time- time stretching beyond what is easy to intuitively grasp.
1b. Toilet paper analogy—if a roll of toilet paper is Earth history, humans reside in the shreds at the end of the very last sheet. (Frolich PowerPoint Slide 4)
(Insert Key Events of History of Life picture / Frolich PowerPoint Slide 5)
C. The Primitive Earth:
1c. Sun and Planets: Probably formed from aggregates of dust particles and debris,taking approx. 10-billion years.
- 4.6 billion years ago: solar system in place.
2c. First atmosphere was probably formed by gases escaping from volcanoes. Therefore, the primitive atmosphere would have been made up of mostly water vapor, nitrogen, and carbon dioxide, along with small amounts of hydrogen and carbon monoxide. (Free oxygen was scarce, if any.)
- Earth was extremely hot, and as it cooled, it formed dense clouds.
- Water vapor condensed to liquid water, and rain began to fall. = Oceans. (Mader 468)
- How do we know? Existing ancient rocks. (Frolich PowerPoint Slide 6)
D. Small Organic Molecules:
1d. Rain washed gases into oceans.
- The great deal of energy present (ie volcanoes, lightning, ultraviolet radiation, etc.) made the primitive gases react with one another and produce small organic compounds, such as nucleotides and amino acids.
- Experiment conducted by Stanley Miller confirms this theory. (Mader 468-469)
(Insert Stanley Miller picture / fig.cox.miami.edu / http://fig.cox.miami.edu/~cmallery/150/life)
(Insert Stanly Miller Experiment picture / Frolich PowerPoint Slide 7)
E. Macromolecules: Newly formed small organic molecules probably joined to produce organic macromolecules.
1e. RNA- first hypothesis: The only macromolecule needed to progress toward formation of the first cell was RNA (ribonucleic acid). It is possible that, then, RNA could have carried out the processes of life commonly associated today with DNA.
2e. Protein-first hypothesis: Amino acids join together when exposed to dry heat. This theory suggests that amino acids collected in shallow puddles, and the heat of the sun caused to to form proteinoids (small polypeptides) that have some catalytic properties. When returned to water, they form microspheres, sturctues that are made of only protein but have mnay of the properties of a cell.
F. The Protocell: Can carry on metablism but not reproduce.
- Could have come about by a lipd that was made available to microspheres, the two tend to associate, and produce a pipid-protein membrane.
- Protocell could have used the abundant small organic molecules in the ocean as food.
- Protocell was most likely a heterotroph: organism that takes in preformed food.
- Also would have been a fementer, since there was no free oxygen. (Mader 469)
(Insert Early Earth picture / Frolich PowerPoint Slide 6)
G. The True Cell: How did the first cell acquire both DNA and enzymatic proteins?
1g. RNA-first Hypothesis: First cell had RNA genes that, similar to mRNA, could have specified protein synthesis. Some of these proteins would have been enzymes. One of these enzymes may have used RNA as a template to form DNA, and replication would have then proceeded normally.
2g. Protein-first Hypothesis: Some of the proteins in the protocell would have evolved the enzymatic ability to synthesize DNA from nucleotides in the ocean. DNA would have then gone on to specify protein synthesis, and the cell could have acquired all its enzymes, inlcuding those that replicate DNA. (Mader 468-469)
II. Biological Evolution
A. Since the first true cells were the simplest of life cells, they must have been prokaryotic cells, lacking a nucleus.
- Eukaryotic cells, which have nuclei, evolved from these first cells.
- Multi-cellular organisms and other kingdoms evolved, like fungi and plants.
B. Biological Evolution: The process by which a species changes throughout time. Two important aspects:
- Descent from a common ancestor, which explains what all living things have a commno chemistry and cellular structure.
- Adaptation to the environment, which enables an organism to survive and reproduce in its environment. (Explains diversity of life.)
C. Common Descent: Life forms change over time and from place to place.
1c. Charles Darwin: English naturlaist who first formulated the teory of evolution based on his travels at the age of 22.
- Gathered evidence to support the idea of common descent, based in fossil, anatomical, and biogeographical data. (Mader 470)
(Insert Charles Darwin picture /www.paracompusa.com / http://www.paracompusa.com/SmartScience/Popa/Vol4-2.html)
D. Evidence for Historical Fact of Evolution
1d. Fossil record
–Most rocks contain fossils (in sedimentary rock). (Frolich PowerPoint Slide 8) Best evidence because they are the actual remains of species that lived on Earth at least 10000 years ago and up to billions of years ago. Includes trails, footprints, burrows, casts, preserved droppings, bone, impressions, and insects trapped in tree resin.
- Paleontologists: Find and remove fossils from strata.
- Fossil Record: History of life recorded by fossils.
(Mader 470)
–Long-term change in biological communities. (Frolich PowerPoint Slide 8)
- In general, life progressed from the simple to the complex: Unicellular prokaryotes, unicellular eukaryotes, multicellular eukaryotes, fishes, terrestial plants, animals. On land, nonflowering plants, flowering plants, amphibians, reptiles (including dinosaurs), birds, etc. (Mader 471)
(Insert picture of Ambulocetus / http://www.flickr.com/ / http://www.flickr.com/photos/68509222@N00/384835318/)
2d. Transitional Fossils: Those that have characteristics of two different groups: origin of mammals, origin of birds.
- Anatomical similarities.
- Shared embryological features.
- Shared biochemical and genetic features.
(Insert Evidence for Historical Fact of Evolution picture / Frolich PowerPoint Slide 8)
(Frolich PowerPoint Slide 8)
E. Different Types of Evidence Support the Hypothesis that Organisms are Related Through Common Descent.
1e. Biogeographical Evidence: Biogeography: The study of the distribution of plants and animals in different places throughout the world.
- Life forms evolved in a particular locale and then spread out, which provides for a variety of plants and animals where geography separates continents, islands, or seas.
- Ex. Rabbits were not found in S. America, though the geography was suited for them, because they evolved somewhere else and could not reach S. America.
2e. Anatomical Evidence: Common Descent allows for the explanation for anatomical similarities among organisms.
- Ex. Forelimbs are used by birds, whales, horses, lizards, and monkeys, for different purposes.
- These are Homologous Structures: similar in structure anatomically because they are inherited from a common ancestor.
- Analogous Structures: Serve the same function, but are not constructed similarly, nor do they share a common ancestry.
- Ex. Wings of birds and insects, the jointed appendages of a lobster, and humans are analogous structures.
- Vestigal Structures: Anatomical features that are fully developed in one group of organisms, but are reduced and may have no function in similar groups.
- Ex. Ancestors of whales walked on land. "Modern" whales have a vestigial pelvic girdle and legs, but are completely aquatic. These are also explained by Common Descent. Traces of evolutionary history.
3e. Biochemical Evidence: Almost all living organisms use the same basic biochemical molecules, including DNA, ATP, etc.
- Therefore, humans share a large number of genes with much simpler organisms. Life's vast diversity has come about by only a slight difference in the regulation of genes.
F. Intelligent Design:
- Evolutionary theory has been supported by repeated scientific experiments and observations.
- Intelligent Design argues that the diversity of life could never have arisen without the involvement of an "intelligent agent". Faith-based, not science-based.
G. Natural Selection: Mechanism for adaptation.
- Adaptation: A species becomes suited to its environment.
- Critical Elements of Natural Selection are as follows:
* Variation: Individual members of a species vary in physical characteristics. Physical variations can be passed from generation to generation.
* Competition for Limited Resources: The number in each generation usually stays about the same: resources are limited and competition for resources reults in unequal reporduction among members of a population.
* Adaptation: Members of a population with advantageous traits capture more resources and are more likely to reproduce and pass on those traits. Over time, the environment "selects" for the better-adapted traits. Therefore, each subsequent generation includes more individuals that are adapted in the same way to the environment.
- Accounts for great diversity of life. (Mader 474)
III. Classification of Humans
A. Biologists classify organisms according to their evolutionary relatedness.
1a. Binomial Name: Each organism has a name that gives its genus and species.
- Organisms in the same domain have general characteristics in common.
- Those in the same genus have very specific characteristics in common.
B. DNA Data and Human Evolution: DNA data is being relied on more heavily today to trace the history of life.
1b. 1970s: Carl Woese reports that on the basis of rRNA data, there are three domains of life and the archaea are more closely related to eukaryotes than to bacteria. Animals are more closely related to fungi than plants. (Mader 475)
(Insert Three Domain System of Classification picture / kilby.sac.on.ca / http://kilby.sac.on.ca/faculty/dgalajda/oacbiology/domains__cladistics.htm)
C. Humans Are Primates
- Our closest living relatives are monkeys and apes (anthropoids).
- We share a common ancestor, most recently with apes, farther into deep time with monkeys and even farther in with lemurs and tarsurs (prosimians).
- The living species are not our actual ancestors—we need the fossil record to see them.
(Frolich PowerPoint Slide 9)
- Primates have mobile limbs (w/ five digits each, opposable thumb); grasping hands; a flattened face; binocular vision (including cones); a large, complex brain; and a reduced reproductive rate.
- All traits shared with humans.
D. Comparing Human Skeleton to the Chimpanzee Skeleton
1d. The genomes of humans and chimpanzees are 99% identical.
- 1% difference: Humans, not chimps, are adapted for an upright stance. (Mader 476-477)
(Insert Human / Chimpanzee Skeletons pictures / http://www.flickr.com/ / http://www.flickr.com/photos/mindfuldocumentation/71000531/)
(Insert Evolution of Primates picture / Frolich PowerPoint Slide 9)
IV. Evolution of Hominids
A. Evolutionary Tree: A working hypothesis of the past history of a group of organisms. (See Evolution of Primates picture.)
B. The First Hominids: Hominid refers to our branch of the evolutionary tree.
- Lineage: Any two lines of descent.
- Each lineage throughout time accumulates genetic changes, which lead to RNA and protein changes.
- Molecular data suggest that hominids split from the ape line of descent about 7 mya.
C. Hominid Features: Anatomical features are used to determine if a fossil is a hominid.
- Bipedal posture: Walking on two feet.
- Shape of the face: Flatter, more pronounced chin.
- Teeth are generally smaller and less specialized.
- Brain size.
D. Earliest Fossil Hominids
- Odest fossil: Sahelanthropus tchadensis, dated 7 mya, found in Chad, central Africa. Only found a skull.
- Orrorin tugenensis: dated 6 mya, found in eastern Africa. Limb anatomy suggests bipedal posture.
- Ardipithecus kadabba: dated between 5.8-5.2 mya.
E. Evolution of Australopithecines: Beginning of hominid line of descent.
- Group of species that evolved and diversified in Africa.
- Some were slender, some were powerful.
- Fed on soft fruits and leaves, some of the more "robust" fed on a more fibrous diet.
- First was unearthed in Southern Africa. (Australopithecus africanus)
- Walked upright. Proportions of limbs were apelike.
- Relatively large brain.
- A. afarensis: Lucy. Dated at 3.18 mya, she stood upright and walked bipedally.
Ape-like above waist (small brain) and humanlike below the waist (walked erect). Proves human characteristics did not evolve all at one time. = Mosaic evolution.
V. Evolution of Humans
A.Fossils are assigned to the genus Homo if the following criteria are met:
- Brain size is 600 cm3 or greater.
- The jaw and teeth resemble those of humans.
- Tool use is evident.
B. Early Homo: Homo habilis "handy man": Dated between 2.0 and 1.9 mya.
- May be ancestral to early humans due to larger brain size, smaller cheek teeth, possibility of speech, and indication of tool use. May have been the beginnings of society and culture, if they hunted and ate together.
(Insert Homo Habilis picture / primatas.no.sapo.pt / http://primatas.no.sapo.pt/homem.htm)
C. Homo Erectus: Fossils found in Africa, Asia, and Europe. Dated between 1.9 and 0.3 mya.
- First H. erectus to be unearthed was in 1891, by Eugene Dubois.
- Several different species are included in this group, although all are similar in appearance.
- Compared with H. habilis, H. erectus had a larger brain and a flatter face. Nose projected, much taller. Were erect, with striding gait. Skeleton still showed some australopithecine features. Believed to have migrated from Africa into Asia and Europe.
- First hominid to use fire, and fashioned more advanced tools than early Homos.
- Believed to have used "home bases".
- Language and culture.
(Insert Homo Erectus picture / www.forcesitaly.org / http://www.forcesitaly.org/italy/immagini?M=D)
D. Evolution of Modern Humans
1d. Most accept the idea that Homo sapiens (modern humans) evolved from H. erectus. (Mader 482-484)
- Ability to interbreed.
- Little anatomical difference among populations.
- Little biochemical difference among populations.
- DNA and protein analysis show recent single common ancestor within 1 million years, perhaps only 200,000 years ago. (Frolich PowerPoint Slide 11)
2d. Multiregional Continuity Hypothesis: Belief that Homo sapiens evolved in several different locations. (ie. Asia, Africa, and Europe.)
3d. Others argue that it is unlikely that evolution would have produced essentially the same result in these different places. They suggest the following theory:
4d. Out-of-Africa Hypothesis: Proposes that H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe and Asia about 100000 years BP. This hypothesis suggests that we are more genetically similar than the other hypothesis, and this is the more accepted hyposthesis of the two.
E. Neandertals:
- First Neandertal discovered in Neander Valley, Germany, approx. 200000 years BP.
- Massive brow ridges, and their nose, jaws and teeth protruded far forward. Low forehead, lower jaw lacked a chin. Brain was slightly larger than modern humans. Heavily muscled. Lived in Europe and Asia during the lst ice age.
- Culturally advanced. May have built houses when not living in caves. Manufactured a variety of stone tools, including spear points. Hunted bears, woolly mammoths, rhinos, etc. Used and controlled fire. Buried their dead w/ flowers. may have even had a religion. Capable of thinking symbolically. (Mader 485)
(Insert Neanderthal and Modern Human Skulls Comparison picture / Frolich PowerPoint Slide 13)
F. Cro-Magnons: Oldest fossils to be designated Homo sapiens.
- Named after fossil location in France.
- Believed to be the modern humans who entered Asia and Europe from Africa 100000 years BP.
- Thoroughly modern appearance.
- Did not interbreed with Neanderthals, but seemed to coexist.
- Made advanced stone tools, including compound tools.
- May have been first to throw spears, and were accomplished hunters.
- Culture included art.
(Insert Cro-Magnon Skull picture / www.skadi.net / http://www.skadi.net/forum/showthread.php?t=11043)
G. Human Variation
1g. Widely distributed about the globe. Different ethnicities.
- Could be due to environmental adaptations. (ie dark and light skin)
- Bergmann's rule: animals in colder regions have a bulkier body build.
- Allen's rule: Animals in colder regions have shorter limbs, digits, and ears, to help regulate body temperature.
II. Biological Evolution
III. Classification of Humans
IV. Evolution of Hominids
V. Evolution of Humans
I. Origin of Life
A. Fundamental Principle of Biology: All living things are made of cells and every cell comes from a preexisting cell.
1a. Chemical Evolution: A slow increase in the complexity of chemicals. (Mader 468)
B. To understand evolution, we must appreciate deep time- time stretching beyond what is easy to intuitively grasp.
1b. Toilet paper analogy—if a roll of toilet paper is Earth history, humans reside in the shreds at the end of the very last sheet. (Frolich PowerPoint Slide 4)
(Insert Key Events of History of Life picture / Frolich PowerPoint Slide 5)
C. The Primitive Earth:
1c. Sun and Planets: Probably formed from aggregates of dust particles and debris,taking approx. 10-billion years.
- 4.6 billion years ago: solar system in place.
2c. First atmosphere was probably formed by gases escaping from volcanoes. Therefore, the primitive atmosphere would have been made up of mostly water vapor, nitrogen, and carbon dioxide, along with small amounts of hydrogen and carbon monoxide. (Free oxygen was scarce, if any.)
- Earth was extremely hot, and as it cooled, it formed dense clouds.
- Water vapor condensed to liquid water, and rain began to fall. = Oceans. (Mader 468)
- How do we know? Existing ancient rocks. (Frolich PowerPoint Slide 6)
D. Small Organic Molecules:
1d. Rain washed gases into oceans.
- The great deal of energy present (ie volcanoes, lightning, ultraviolet radiation, etc.) made the primitive gases react with one another and produce small organic compounds, such as nucleotides and amino acids.
- Experiment conducted by Stanley Miller confirms this theory. (Mader 468-469)
(Insert Stanley Miller picture / fig.cox.miami.edu / http://fig.cox.miami.edu/~cmallery/150/life)
(Insert Stanly Miller Experiment picture / Frolich PowerPoint Slide 7)
E. Macromolecules: Newly formed small organic molecules probably joined to produce organic macromolecules.
1e. RNA- first hypothesis: The only macromolecule needed to progress toward formation of the first cell was RNA (ribonucleic acid). It is possible that, then, RNA could have carried out the processes of life commonly associated today with DNA.
2e. Protein-first hypothesis: Amino acids join together when exposed to dry heat. This theory suggests that amino acids collected in shallow puddles, and the heat of the sun caused to to form proteinoids (small polypeptides) that have some catalytic properties. When returned to water, they form microspheres, sturctues that are made of only protein but have mnay of the properties of a cell.
F. The Protocell: Can carry on metablism but not reproduce.
- Could have come about by a lipd that was made available to microspheres, the two tend to associate, and produce a pipid-protein membrane.
- Protocell could have used the abundant small organic molecules in the ocean as food.
- Protocell was most likely a heterotroph: organism that takes in preformed food.
- Also would have been a fementer, since there was no free oxygen. (Mader 469)
(Insert Early Earth picture / Frolich PowerPoint Slide 6)
G. The True Cell: How did the first cell acquire both DNA and enzymatic proteins?
1g. RNA-first Hypothesis: First cell had RNA genes that, similar to mRNA, could have specified protein synthesis. Some of these proteins would have been enzymes. One of these enzymes may have used RNA as a template to form DNA, and replication would have then proceeded normally.
2g. Protein-first Hypothesis: Some of the proteins in the protocell would have evolved the enzymatic ability to synthesize DNA from nucleotides in the ocean. DNA would have then gone on to specify protein synthesis, and the cell could have acquired all its enzymes, inlcuding those that replicate DNA. (Mader 468-469)
II. Biological Evolution
A. Since the first true cells were the simplest of life cells, they must have been prokaryotic cells, lacking a nucleus.
- Eukaryotic cells, which have nuclei, evolved from these first cells.
- Multi-cellular organisms and other kingdoms evolved, like fungi and plants.
B. Biological Evolution: The process by which a species changes throughout time. Two important aspects:
- Descent from a common ancestor, which explains what all living things have a commno chemistry and cellular structure.
- Adaptation to the environment, which enables an organism to survive and reproduce in its environment. (Explains diversity of life.)
C. Common Descent: Life forms change over time and from place to place.
1c. Charles Darwin: English naturlaist who first formulated the teory of evolution based on his travels at the age of 22.
- Gathered evidence to support the idea of common descent, based in fossil, anatomical, and biogeographical data. (Mader 470)
(Insert Charles Darwin picture /www.paracompusa.com / http://www.paracompusa.com/SmartScience/Popa/Vol4-2.html)
D. Evidence for Historical Fact of Evolution
1d. Fossil record
–Most rocks contain fossils (in sedimentary rock). (Frolich PowerPoint Slide 8) Best evidence because they are the actual remains of species that lived on Earth at least 10000 years ago and up to billions of years ago. Includes trails, footprints, burrows, casts, preserved droppings, bone, impressions, and insects trapped in tree resin.
- Paleontologists: Find and remove fossils from strata.
- Fossil Record: History of life recorded by fossils.
(Mader 470)
–Long-term change in biological communities. (Frolich PowerPoint Slide 8)
- In general, life progressed from the simple to the complex: Unicellular prokaryotes, unicellular eukaryotes, multicellular eukaryotes, fishes, terrestial plants, animals. On land, nonflowering plants, flowering plants, amphibians, reptiles (including dinosaurs), birds, etc. (Mader 471)
(Insert picture of Ambulocetus / http://www.flickr.com/ / http://www.flickr.com/photos/68509222@N00/384835318/)
2d. Transitional Fossils: Those that have characteristics of two different groups: origin of mammals, origin of birds.
- Anatomical similarities.
- Shared embryological features.
- Shared biochemical and genetic features.
(Insert Evidence for Historical Fact of Evolution picture / Frolich PowerPoint Slide 8)
(Frolich PowerPoint Slide 8)
E. Different Types of Evidence Support the Hypothesis that Organisms are Related Through Common Descent.
1e. Biogeographical Evidence: Biogeography: The study of the distribution of plants and animals in different places throughout the world.
- Life forms evolved in a particular locale and then spread out, which provides for a variety of plants and animals where geography separates continents, islands, or seas.
- Ex. Rabbits were not found in S. America, though the geography was suited for them, because they evolved somewhere else and could not reach S. America.
2e. Anatomical Evidence: Common Descent allows for the explanation for anatomical similarities among organisms.
- Ex. Forelimbs are used by birds, whales, horses, lizards, and monkeys, for different purposes.
- These are Homologous Structures: similar in structure anatomically because they are inherited from a common ancestor.
- Analogous Structures: Serve the same function, but are not constructed similarly, nor do they share a common ancestry.
- Ex. Wings of birds and insects, the jointed appendages of a lobster, and humans are analogous structures.
- Vestigal Structures: Anatomical features that are fully developed in one group of organisms, but are reduced and may have no function in similar groups.
- Ex. Ancestors of whales walked on land. "Modern" whales have a vestigial pelvic girdle and legs, but are completely aquatic. These are also explained by Common Descent. Traces of evolutionary history.
3e. Biochemical Evidence: Almost all living organisms use the same basic biochemical molecules, including DNA, ATP, etc.
- Therefore, humans share a large number of genes with much simpler organisms. Life's vast diversity has come about by only a slight difference in the regulation of genes.
F. Intelligent Design:
- Evolutionary theory has been supported by repeated scientific experiments and observations.
- Intelligent Design argues that the diversity of life could never have arisen without the involvement of an "intelligent agent". Faith-based, not science-based.
G. Natural Selection: Mechanism for adaptation.
- Adaptation: A species becomes suited to its environment.
- Critical Elements of Natural Selection are as follows:
* Variation: Individual members of a species vary in physical characteristics. Physical variations can be passed from generation to generation.
* Competition for Limited Resources: The number in each generation usually stays about the same: resources are limited and competition for resources reults in unequal reporduction among members of a population.
* Adaptation: Members of a population with advantageous traits capture more resources and are more likely to reproduce and pass on those traits. Over time, the environment "selects" for the better-adapted traits. Therefore, each subsequent generation includes more individuals that are adapted in the same way to the environment.
- Accounts for great diversity of life. (Mader 474)
III. Classification of Humans
A. Biologists classify organisms according to their evolutionary relatedness.
1a. Binomial Name: Each organism has a name that gives its genus and species.
- Organisms in the same domain have general characteristics in common.
- Those in the same genus have very specific characteristics in common.
B. DNA Data and Human Evolution: DNA data is being relied on more heavily today to trace the history of life.
1b. 1970s: Carl Woese reports that on the basis of rRNA data, there are three domains of life and the archaea are more closely related to eukaryotes than to bacteria. Animals are more closely related to fungi than plants. (Mader 475)
(Insert Three Domain System of Classification picture / kilby.sac.on.ca / http://kilby.sac.on.ca/faculty/dgalajda/oacbiology/domains__cladistics.htm)
C. Humans Are Primates
- Our closest living relatives are monkeys and apes (anthropoids).
- We share a common ancestor, most recently with apes, farther into deep time with monkeys and even farther in with lemurs and tarsurs (prosimians).
- The living species are not our actual ancestors—we need the fossil record to see them.
(Frolich PowerPoint Slide 9)
- Primates have mobile limbs (w/ five digits each, opposable thumb); grasping hands; a flattened face; binocular vision (including cones); a large, complex brain; and a reduced reproductive rate.
- All traits shared with humans.
D. Comparing Human Skeleton to the Chimpanzee Skeleton
1d. The genomes of humans and chimpanzees are 99% identical.
- 1% difference: Humans, not chimps, are adapted for an upright stance. (Mader 476-477)
(Insert Human / Chimpanzee Skeletons pictures / http://www.flickr.com/ / http://www.flickr.com/photos/mindfuldocumentation/71000531/)
(Insert Evolution of Primates picture / Frolich PowerPoint Slide 9)
IV. Evolution of Hominids
A. Evolutionary Tree: A working hypothesis of the past history of a group of organisms. (See Evolution of Primates picture.)
B. The First Hominids: Hominid refers to our branch of the evolutionary tree.
- Lineage: Any two lines of descent.
- Each lineage throughout time accumulates genetic changes, which lead to RNA and protein changes.
- Molecular data suggest that hominids split from the ape line of descent about 7 mya.
C. Hominid Features: Anatomical features are used to determine if a fossil is a hominid.
- Bipedal posture: Walking on two feet.
- Shape of the face: Flatter, more pronounced chin.
- Teeth are generally smaller and less specialized.
- Brain size.
D. Earliest Fossil Hominids
- Odest fossil: Sahelanthropus tchadensis, dated 7 mya, found in Chad, central Africa. Only found a skull.
- Orrorin tugenensis: dated 6 mya, found in eastern Africa. Limb anatomy suggests bipedal posture.
- Ardipithecus kadabba: dated between 5.8-5.2 mya.
E. Evolution of Australopithecines: Beginning of hominid line of descent.
- Group of species that evolved and diversified in Africa.
- Some were slender, some were powerful.
- Fed on soft fruits and leaves, some of the more "robust" fed on a more fibrous diet.
- First was unearthed in Southern Africa. (Australopithecus africanus)
- Walked upright. Proportions of limbs were apelike.
- Relatively large brain.
- A. afarensis: Lucy. Dated at 3.18 mya, she stood upright and walked bipedally.
Ape-like above waist (small brain) and humanlike below the waist (walked erect). Proves human characteristics did not evolve all at one time. = Mosaic evolution.
V. Evolution of Humans
A.Fossils are assigned to the genus Homo if the following criteria are met:
- Brain size is 600 cm3 or greater.
- The jaw and teeth resemble those of humans.
- Tool use is evident.
B. Early Homo: Homo habilis "handy man": Dated between 2.0 and 1.9 mya.
- May be ancestral to early humans due to larger brain size, smaller cheek teeth, possibility of speech, and indication of tool use. May have been the beginnings of society and culture, if they hunted and ate together.
(Insert Homo Habilis picture / primatas.no.sapo.pt / http://primatas.no.sapo.pt/homem.htm)
C. Homo Erectus: Fossils found in Africa, Asia, and Europe. Dated between 1.9 and 0.3 mya.
- First H. erectus to be unearthed was in 1891, by Eugene Dubois.
- Several different species are included in this group, although all are similar in appearance.
- Compared with H. habilis, H. erectus had a larger brain and a flatter face. Nose projected, much taller. Were erect, with striding gait. Skeleton still showed some australopithecine features. Believed to have migrated from Africa into Asia and Europe.
- First hominid to use fire, and fashioned more advanced tools than early Homos.
- Believed to have used "home bases".
- Language and culture.
(Insert Homo Erectus picture / www.forcesitaly.org / http://www.forcesitaly.org/italy/immagini?M=D)
D. Evolution of Modern Humans
1d. Most accept the idea that Homo sapiens (modern humans) evolved from H. erectus. (Mader 482-484)
- Ability to interbreed.
- Little anatomical difference among populations.
- Little biochemical difference among populations.
- DNA and protein analysis show recent single common ancestor within 1 million years, perhaps only 200,000 years ago. (Frolich PowerPoint Slide 11)
2d. Multiregional Continuity Hypothesis: Belief that Homo sapiens evolved in several different locations. (ie. Asia, Africa, and Europe.)
3d. Others argue that it is unlikely that evolution would have produced essentially the same result in these different places. They suggest the following theory:
4d. Out-of-Africa Hypothesis: Proposes that H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe and Asia about 100000 years BP. This hypothesis suggests that we are more genetically similar than the other hypothesis, and this is the more accepted hyposthesis of the two.
E. Neandertals:
- First Neandertal discovered in Neander Valley, Germany, approx. 200000 years BP.
- Massive brow ridges, and their nose, jaws and teeth protruded far forward. Low forehead, lower jaw lacked a chin. Brain was slightly larger than modern humans. Heavily muscled. Lived in Europe and Asia during the lst ice age.
- Culturally advanced. May have built houses when not living in caves. Manufactured a variety of stone tools, including spear points. Hunted bears, woolly mammoths, rhinos, etc. Used and controlled fire. Buried their dead w/ flowers. may have even had a religion. Capable of thinking symbolically. (Mader 485)
(Insert Neanderthal and Modern Human Skulls Comparison picture / Frolich PowerPoint Slide 13)
F. Cro-Magnons: Oldest fossils to be designated Homo sapiens.
- Named after fossil location in France.
- Believed to be the modern humans who entered Asia and Europe from Africa 100000 years BP.
- Thoroughly modern appearance.
- Did not interbreed with Neanderthals, but seemed to coexist.
- Made advanced stone tools, including compound tools.
- May have been first to throw spears, and were accomplished hunters.
- Culture included art.
(Insert Cro-Magnon Skull picture / www.skadi.net / http://www.skadi.net/forum/showthread.php?t=11043)
G. Human Variation
1g. Widely distributed about the globe. Different ethnicities.
- Could be due to environmental adaptations. (ie dark and light skin)
- Bergmann's rule: animals in colder regions have a bulkier body build.
- Allen's rule: Animals in colder regions have shorter limbs, digits, and ears, to help regulate body temperature.
Thursday, July 17, 2008
Embryonic and Fetal Development Online Lab
Rotation
8 Weeks- All Major Body Parts are Present
Umbilical Cord Forms
Implantation
Fertilization
10 Significant Events During Embryonic / Fetal Development:
Event 1: Fertilization:
-What: Sperm penetrates the oocyte. The fusion of the oocyte with the sperm nuclei is the creation of the zygote.
- When: 1 day post ovulation.
- Why it is significant: Obviously, without this event, there would be no pregnancy / baby. I find it amazing that there is such a small period of time for fertilization to occur: ovulation usually only lasts approximately 24 hours.
Event 2: Implantation:
- What: Embryo implants itself into wall of uterus. Chorion secretes enzymes to digest away some of the tissue and blood vessels of the endometrium of the uterus.
- When: Week 2
- Why: It is important that the embryo implants in the right place, which is the uterus. The uterus sustains a healthy pregnancy. If an embryo does not implant, it results in a miscarriage. If it implants in the wrong place, like in the oviduct, it will result in an ectopic pregnancy, which is not a viable pregnancy.
Event 3: Development of Nervous System & Heart:
- What: Nervous system is first organ system to appear. Thickening appears along entire length of embryo, and invagination occurs as neural folds appear. When neural folds meet at midline, the neural tube is formed, which later develops into brain and spinal cord. Development of heart: first, there are right and left tubes, which fuse, and heart begins pumping blood.
- When: Weeks 3 & 4
- Why: These organ systems are vital to a healthy baby.
Event 4: Heartbeat can be detected.
What: The heart is fully functional, and can be seen on an ultrasound.
When: Week 4
Why: Doctors say that once a heart beat is seen, the chances of a successful pregnancy are much higher than before.
Event 5: Umbilical Cord is formed.
What: A "body stalk" connects the embryo to the chorion, and also contains the extrembryonic membrane, the allantois. Its blood vessels become the umbilical blood vessels. Head and tail then lift up, and the body stalk moves anteriorly by constriction. When this process if finished, the umbilical cord is fully formed, and it connects the developing embryo to the placenta.
When: Weeks 4-5
Why: The umbilical cord is a fetus' source of nourishment and survival.
Event 6: Brain Waves can be detected.
What: I don't really have much information for this, because I found this fact at some other website I had gone to to research the development of embryos. All I know is that the brain is functioning enough to have the waves detected.
When: Week 6
Why: I figure once the brain is fully functioning, and can be detected, it is another strong sign that the fetus is developing the way it should, and that it is strong and healthy.
Event 7: All Major Body Parts are now Present.
What: To think that a tiny little embryo (1.5 inches) has already formed all of it's major body parts!
When: Week 8
Why: Significant because it's so early in development, but all the major parts are present. (Sorry, I know it sounds repetitive, but I don't know how else to say it.)
Event 8: Ossification occurs.
What: Cartilage begins to be replaced by bone as ossification centers appear in most of the bones.
When: Month 3-4
Why: Again, a great sign of growth. When this happens, the fetus becomes "stronger", and things are developing as they should.
Event 9: Fetal Movement.
What: Although the embryo is able to move at approx. 5 weeks, fetal movement can be detected by the mother around 20 weeks for first-time mothers, and as early as 16 weeks for mothers who have had babies previously.
When: Months 4-5, depending.
Why: Fetal movement that is strong enough for a mother to feel is important because it is an indication of a healthy baby. If a mother goes a certain period of time without feeling any movement, she knows the fetus may be in distress, and can seek medical attention.
Event 10: Rotation and Birth
What: The fetus usually rotates so that its head is pointed toward the cervix. This is in preparation for birth through the birth canal. Birth- the fetus is pushed downward by contractions, the cervix stretches and the baby makes its appearance to the world.
When: Months 8-9
Why: Rotation is important because a delivery of a baby that has not rotated is much more dangerous to the fetus. The head should come out first so that the "biggest" part of the baby comes out first. When this doesn't happen, the baby can get stuck. Birth is important for obvious reasons.
Wednesday, July 16, 2008
Chapter 17 Compendium Review- Pictures
Process of Birth
Stages of Pregnancy
Fetus- 7 Months
Fetus- 4 Months
Fetal Blood Circulation
Embryo- 8 Weeks
Pre-Embryonic Development
Cleavage
Stages of Fertilization
Chapter 17 Compendium Review
I. Fertilization
II. Pre-Embryonic and Embryonic Development
III. Fetal Development
IV. Pregnancy and Birth
V. Development After Birth
I. Fertilization
A. Fertilization is the union of a sperm and egg to form a zygote, the first cell of the new individual.
- Only the nucleus from the sperm head fuses with the nucleus of the egg.
- Zygote receives cytoplasm and organelles only from mother.
- Although several sperm penetrate the corona radiata ( few layers of adhering follicular cells), and several sperm attempt to penetrate the zona pellucida (the extracellular matrix surrounding the egg), only one sperm enters the egg.
- Sperm head binds tightly to zona pellucida, and acrosome releases digestive enzymes that create a pathway for the sperm through the zona pellucida.
- When the sperm binds to the egg, their plasma membranes fuse, and this sperm enters the egg entirely.
- Fusion of nucleus' occur.
- As soon as sperm touches egg, the egg's plasma membrane depolarizes to prevent the binding of any other sperm.
- Zona pellucida becomes impenetrable from any further fertilization.
(Insert Stages of Fertilization picture / http://www.fiu.edu/ / http://www.fiu.edu/~srose/femsexfiu/pregnancy.html)
II. Pre-Embryonic and Embryonic Development
A. Processes of Development:
1a. Cleavage: Immediately after fertilization, they zygote divides so that there are first 2, then 4, 8, 16, and 32 cells, etc.
- No increase in size.
-Mitotic: Each cell receives a full complement of chromosomes and genes.
(Insert Cleavage picture / dtc.pima.edu / http://dtc.pima.edu/~biology/202alpha/lesson13/lesson13c.htm)
2a. Growth: During embryonic development, cell division is accompanied by an increase in size of daughter cells.
3a. Morphogenesis: Shaping of embryo. First evident when cells move, or migrate, in relation to other cells.
4a. Differentiation: Cells take on specific structure and function. Nervous system is first.
B. Extraembryonic Membranes
1b. Not part of embryo and fetus; located outside of embryo.
2b. Chorion: Develops into fetal half of placenta, which gives embryo / fetus nourishment and oxygen and takes away its waste.
3b. Allantois: Extends away from embryo. Accumulates small amount of urine produced by fetal kidneys and gives rise to urinary bladder. Its blood vessels become umbilical blood vessels, to take blood to and from fetus.
4b. Yolk Sac: First embryonic membrane to appear. First site of blood cell formation.
5b. Amnion: Enlarges as embryo and then fetus enlarges. Contains fluid to cushion and protect embryo.
C. Stages of Development
1c. Fertilization to Birth
- 280 days = gestation period.
2c. Pre-embryonic development: Events of first week.
- Morula: Compact ball of embryonic cells that become a blastocyst.
- Inner Cell Mass: the cells of the blastocyst arrange themselves so that there is an inner cell mass surrounded by an outer layer of cells. Inner cell mass will become embryo, and the layer of cells will become the chorion.
(Insert Pre-embryonic Development picture / Frolich PowerPoint Slide 19)
3c. Embryonic Development: Begins with second week and lasts until end of second month of development.
- Second Week: Embryo begins process of implanting itself in the wall of uterus at end of first week.
- At this point, embryo is approx. the size of a period. ( . )
- As week progresses, the inner cell mass becomes the embryonic disk, and two more extraembryonic membranes form. (Yolk sac, and amniotic cavity.) (Mader 354-357)
- Gastrulation: turns inner cell mass into embryonic disk. Example of morphogenesis, when cells move or migrate, in this case to become tissue layers called the primary germ layers.
- By completion of gastrulation, embryonic disk has become an embryo with three germ layers: ectoderm, mesoderm, and endoderm. (Mader 358)
- Fetal “germ layers” destined to become specific adult structures. (Frolich PowerPoint Slide 21)
4c. Third Week: Appearance of two organ systems:
- Nervous System
- Heart
5c. Fourth and Fifth Week:
- Body stalk (future umbilical cord) connects embryo to the chorion which has projections called chorionic villi.
- Umbilical cord is formed.
- Limb buds appear.
- Head enlarges.
- Sense organs become more prominent.
- Can make out developing eyes, ears, and nose.
6c. Sixth through Eighth Weeks:
- Form becomes easily recognizable as human.
- Nervous system allows for reflex movement.
- Embryo is approx. 1.5 in long.
- All organ systems are established. (Mader 359)
(Insert Embryo at 8 Weeks Picture / epigee.org / http://epigee.org/pregnancy/methods.html)
4c. Ectopic pregnancy—fertilized egg implants but not in uterine wall. (Frolich PowerPoint Slide 19)
- This pregnancy cannot be successful, because oviduct is unable to support it.
III. Fetal Development
A. Carbon dioxide and other wastes move from the fetal side to the maternal side, and nutrients and wastes move from the maternal side to the fetal side of the placenta by diffusion.
B. Path of Fetal Blood: Umbilical vein carries blood rich in nutrients and O2 away from placenta and to fetus.
- Blood is returned to right atrium.
- Mixed blood enters heart.
- All blood entering right atrium by-passes the lungs.
(Mader 361)
(Insert Fetal Blood Circulation Picture / http://www.brainconnection.com/ / http://www.brainconnection.com/topics?main=gal/fetal-circulation)
C. Events of Fetal Development: Months 3-9
1c. Months 3-4
- Beginning of 3rd month, fetal head is still very big relative to the rest of the body.
- Head growth slows, rest of body increases in length.
- Epidermal refinements (fingernails, eyelashes, eyebrows, etc.) appear.
- Cartilage begins to be replaced by bone.
- Fontanels: Six large membranous areas in skull.
- Possible to distinguish sex sometime in 3rd month.
- During 4th month, fetal heartbeat can be heard through stethoscope.
- By the end of this month, fetus is approx. 6 inches long.
(Insert Fetus- 4 Months picture / epigee.org / http://epigee.org/fetal2.html)
2c. Months 5-7
- Mother begins to feel movement.
- Lanugo: Fine down that covers the translucent skin of fetus.
- Vernix Caseosa: Coats lanugo, to protect skin from amniotic fluid.
- Eyelids fully open.
- Approx. 12 inches long.
(Insert Fetus - 7 Months picture / http://answers.yahoo.com/question?qid=1006052905521)
3c. Months 8-9
- By end of 9th month, fetus is approx. 20.5 in.
- Accumulation of fat occurs.
- Breech birth: Baby comes "rump" first.
- C-Section: Birth through incision and extraction. (Mader 363)
D. Development of Male and Female Genitals
1d. Sex of individual is determined at the moment of fertilization: Males have X and Y chromosomes, females have two X chromosomes.
2d. Internal Genitals:
- Gonads develop during 7th week of development.
- At 14 weeks, sperm or tiny follicles in ovaries are already developing.
3d. External Genitals:
- Tissues are indifferent at first.
- By 14 weeks, the "groove" persists if female, disappears int scrotum if male.
4d. Abnormal Development of Genitals:
- Some XY individuals become females, because a piece of the Y chromosome is missing.
- Some XX individuals become males, because the same small piece is present on an X chromosome.
5d. Ambiguous Sex Determination: Individual has external appearance of a female, although the gonads of a female are absent.
- Androgen Insensitivity Syndrome: Testes produces hormones, but individual develops as a female because the plasma membrane receptors for testosterone are ineffective. External genitalia develop as female. (Mader 365)
IV. Pregnancy and Birth
A. Placental Hormones cause the changes in a mother's body during pregnancy.
1a. Energy level fluctuates.
- Nausea, vomiting.
- Loss of appetite.
- Fatigue.
- Weight gain results from all of the following: breast and uterine enlargement, weight of fetus, amount of amniotic fluid, size of placenta, her own increase in body fluids, increase in storage of proteins, fats, and minerals. Can lead to lower back pain.
2a. Uterus relaxes:
- Increase in blood volume.
- Blood flow rises significantly.
- Smooth muscle relaxation.
3a. Pulmonary Values Increase.
- Increased size of uterus.
- Occupies most of abdominal cavity.
- Pushes intestines, liver, stomach, and diaphragm from top, and widens thoracic cavity.
- Blood carbon dioxide levels fall.
4a. Other Effects:
- Compression of ureters and bladder causes frequent passage of urine.
- Stretch marks.
- Possibility of pregnancy-induced diabetes. (Mader 368)
–Bladder, rectum pushed superiorly, squeezed--change in urination, defecation patterns.
–Stomach compressed--eat more often, less at each meal.
–Immune response may change appetite to avoid possible poisons for fetus.
- Postural changes to compensate for anterior weight.
- Breasts enlarge--first milk production. (Frolich PowerPoint Slide 22)
(Insert Stages of Pregnancy picture / pregnancy.more4kids.info / http://pregnancy.more4kids.info/category/stages-of-pregnancy)
B. Birth:
- Uterus contracts throughout pregnancy.
- Braxton Hicks Contractions: False labor.
- Uterine contractions push fetus downwards, and cervix stretches.
- Parturition: Process of giving birth to an offspring.
- Loss of mucous plug, that during pregnancy, keeps out bacteria and other sperm.
1b. Stage 1: Contractions cause cervical canal to slowly disappear, and lower part of uterus is pulled up toward baby's head, = Effacement.
- Baby's head helps cervical dilation.
- Amniotic membrane ruptures.
2b. Stage 2: Contractions occur every 1-2 mins.
- Desire to push.
- Episiotomy: incision to enlarge opening of vagina, to allow for birth.
- Umbilical cord is cut and tied.
3b. Stage 3: Afterbirth: Placenta is delivered.
(Mader 369)
(Insert Process of Birth picture / Frolich PowerPoint Slide 23)
V. Development After Birth
A. Stages of life: Infancy, childhood, adolescence, and adulthood.
1a. Gerontology: Study of aging.
- Human life span maximum: 120-125 years.
2a. Hypotheses of Aging
- Genetic in Origin: Aging has genetic basis.
- Some genes decrease life span. When inactive, the mitochondria do not produce energy, and the cell uses alternative pathways. Defective mitochondria may produce more free radicals than usual. Caloric restriction can shut down the genes that decrease life span.
- Whole-Body Process: Decline in hormonal system can affect many different organs of body.
- Perhaps aging results from loss of hormonal activities and a decline in functions they control.
- Aging may be due to a specific type of tissue change that affects all organs and even the genes.
- Extrinsic Factors: Diet, exercise, cigarette smoking, heavy alcohol intake, inadequate calcium intake, etc.
B. Effect of Age on Body Systems:
1b. Skin: Skin becomes thinner and less elastic because the number of elastic fibers decreases and collagen fibers undergo cross-linking. = sagging and wrinkling.
2b. Processing and Transporting:
- Cardiovascular disorders are leading cause of death today.
- Arteries become more rigid with time.
- Heart shrinks due to reduction in cardiac muscle cell size.
- Blood flow to liver and kidneys is reduced.
- Respiratory disorders.
- Loss of teeth.
3b. Integration and Coordination:
- Reaction time slows.
- Hearing, taste, and smell receptors need more stimulation.
- Lens of eyes do not accommodate as well as before.
- Loss of skeletal muscle mass.
- Decline of bone density.
- Weight gain.
4b. Reproductive System
- Females undergo menopause.
- Males undergo andropause.
(Mader 370-372)
II. Pre-Embryonic and Embryonic Development
III. Fetal Development
IV. Pregnancy and Birth
V. Development After Birth
I. Fertilization
A. Fertilization is the union of a sperm and egg to form a zygote, the first cell of the new individual.
- Only the nucleus from the sperm head fuses with the nucleus of the egg.
- Zygote receives cytoplasm and organelles only from mother.
- Although several sperm penetrate the corona radiata ( few layers of adhering follicular cells), and several sperm attempt to penetrate the zona pellucida (the extracellular matrix surrounding the egg), only one sperm enters the egg.
- Sperm head binds tightly to zona pellucida, and acrosome releases digestive enzymes that create a pathway for the sperm through the zona pellucida.
- When the sperm binds to the egg, their plasma membranes fuse, and this sperm enters the egg entirely.
- Fusion of nucleus' occur.
- As soon as sperm touches egg, the egg's plasma membrane depolarizes to prevent the binding of any other sperm.
- Zona pellucida becomes impenetrable from any further fertilization.
(Insert Stages of Fertilization picture / http://www.fiu.edu/ / http://www.fiu.edu/~srose/femsexfiu/pregnancy.html)
II. Pre-Embryonic and Embryonic Development
A. Processes of Development:
1a. Cleavage: Immediately after fertilization, they zygote divides so that there are first 2, then 4, 8, 16, and 32 cells, etc.
- No increase in size.
-Mitotic: Each cell receives a full complement of chromosomes and genes.
(Insert Cleavage picture / dtc.pima.edu / http://dtc.pima.edu/~biology/202alpha/lesson13/lesson13c.htm)
2a. Growth: During embryonic development, cell division is accompanied by an increase in size of daughter cells.
3a. Morphogenesis: Shaping of embryo. First evident when cells move, or migrate, in relation to other cells.
4a. Differentiation: Cells take on specific structure and function. Nervous system is first.
B. Extraembryonic Membranes
1b. Not part of embryo and fetus; located outside of embryo.
2b. Chorion: Develops into fetal half of placenta, which gives embryo / fetus nourishment and oxygen and takes away its waste.
3b. Allantois: Extends away from embryo. Accumulates small amount of urine produced by fetal kidneys and gives rise to urinary bladder. Its blood vessels become umbilical blood vessels, to take blood to and from fetus.
4b. Yolk Sac: First embryonic membrane to appear. First site of blood cell formation.
5b. Amnion: Enlarges as embryo and then fetus enlarges. Contains fluid to cushion and protect embryo.
C. Stages of Development
1c. Fertilization to Birth
- 280 days = gestation period.
2c. Pre-embryonic development: Events of first week.
- Morula: Compact ball of embryonic cells that become a blastocyst.
- Inner Cell Mass: the cells of the blastocyst arrange themselves so that there is an inner cell mass surrounded by an outer layer of cells. Inner cell mass will become embryo, and the layer of cells will become the chorion.
(Insert Pre-embryonic Development picture / Frolich PowerPoint Slide 19)
3c. Embryonic Development: Begins with second week and lasts until end of second month of development.
- Second Week: Embryo begins process of implanting itself in the wall of uterus at end of first week.
- At this point, embryo is approx. the size of a period. ( . )
- As week progresses, the inner cell mass becomes the embryonic disk, and two more extraembryonic membranes form. (Yolk sac, and amniotic cavity.) (Mader 354-357)
- Gastrulation: turns inner cell mass into embryonic disk. Example of morphogenesis, when cells move or migrate, in this case to become tissue layers called the primary germ layers.
- By completion of gastrulation, embryonic disk has become an embryo with three germ layers: ectoderm, mesoderm, and endoderm. (Mader 358)
- Fetal “germ layers” destined to become specific adult structures. (Frolich PowerPoint Slide 21)
4c. Third Week: Appearance of two organ systems:
- Nervous System
- Heart
5c. Fourth and Fifth Week:
- Body stalk (future umbilical cord) connects embryo to the chorion which has projections called chorionic villi.
- Umbilical cord is formed.
- Limb buds appear.
- Head enlarges.
- Sense organs become more prominent.
- Can make out developing eyes, ears, and nose.
6c. Sixth through Eighth Weeks:
- Form becomes easily recognizable as human.
- Nervous system allows for reflex movement.
- Embryo is approx. 1.5 in long.
- All organ systems are established. (Mader 359)
(Insert Embryo at 8 Weeks Picture / epigee.org / http://epigee.org/pregnancy/methods.html)
4c. Ectopic pregnancy—fertilized egg implants but not in uterine wall. (Frolich PowerPoint Slide 19)
- This pregnancy cannot be successful, because oviduct is unable to support it.
III. Fetal Development
A. Carbon dioxide and other wastes move from the fetal side to the maternal side, and nutrients and wastes move from the maternal side to the fetal side of the placenta by diffusion.
B. Path of Fetal Blood: Umbilical vein carries blood rich in nutrients and O2 away from placenta and to fetus.
- Blood is returned to right atrium.
- Mixed blood enters heart.
- All blood entering right atrium by-passes the lungs.
(Mader 361)
(Insert Fetal Blood Circulation Picture / http://www.brainconnection.com/ / http://www.brainconnection.com/topics?main=gal/fetal-circulation)
C. Events of Fetal Development: Months 3-9
1c. Months 3-4
- Beginning of 3rd month, fetal head is still very big relative to the rest of the body.
- Head growth slows, rest of body increases in length.
- Epidermal refinements (fingernails, eyelashes, eyebrows, etc.) appear.
- Cartilage begins to be replaced by bone.
- Fontanels: Six large membranous areas in skull.
- Possible to distinguish sex sometime in 3rd month.
- During 4th month, fetal heartbeat can be heard through stethoscope.
- By the end of this month, fetus is approx. 6 inches long.
(Insert Fetus- 4 Months picture / epigee.org / http://epigee.org/fetal2.html)
2c. Months 5-7
- Mother begins to feel movement.
- Lanugo: Fine down that covers the translucent skin of fetus.
- Vernix Caseosa: Coats lanugo, to protect skin from amniotic fluid.
- Eyelids fully open.
- Approx. 12 inches long.
(Insert Fetus - 7 Months picture / http://answers.yahoo.com/question?qid=1006052905521)
3c. Months 8-9
- By end of 9th month, fetus is approx. 20.5 in.
- Accumulation of fat occurs.
- Breech birth: Baby comes "rump" first.
- C-Section: Birth through incision and extraction. (Mader 363)
D. Development of Male and Female Genitals
1d. Sex of individual is determined at the moment of fertilization: Males have X and Y chromosomes, females have two X chromosomes.
2d. Internal Genitals:
- Gonads develop during 7th week of development.
- At 14 weeks, sperm or tiny follicles in ovaries are already developing.
3d. External Genitals:
- Tissues are indifferent at first.
- By 14 weeks, the "groove" persists if female, disappears int scrotum if male.
4d. Abnormal Development of Genitals:
- Some XY individuals become females, because a piece of the Y chromosome is missing.
- Some XX individuals become males, because the same small piece is present on an X chromosome.
5d. Ambiguous Sex Determination: Individual has external appearance of a female, although the gonads of a female are absent.
- Androgen Insensitivity Syndrome: Testes produces hormones, but individual develops as a female because the plasma membrane receptors for testosterone are ineffective. External genitalia develop as female. (Mader 365)
IV. Pregnancy and Birth
A. Placental Hormones cause the changes in a mother's body during pregnancy.
1a. Energy level fluctuates.
- Nausea, vomiting.
- Loss of appetite.
- Fatigue.
- Weight gain results from all of the following: breast and uterine enlargement, weight of fetus, amount of amniotic fluid, size of placenta, her own increase in body fluids, increase in storage of proteins, fats, and minerals. Can lead to lower back pain.
2a. Uterus relaxes:
- Increase in blood volume.
- Blood flow rises significantly.
- Smooth muscle relaxation.
3a. Pulmonary Values Increase.
- Increased size of uterus.
- Occupies most of abdominal cavity.
- Pushes intestines, liver, stomach, and diaphragm from top, and widens thoracic cavity.
- Blood carbon dioxide levels fall.
4a. Other Effects:
- Compression of ureters and bladder causes frequent passage of urine.
- Stretch marks.
- Possibility of pregnancy-induced diabetes. (Mader 368)
–Bladder, rectum pushed superiorly, squeezed--change in urination, defecation patterns.
–Stomach compressed--eat more often, less at each meal.
–Immune response may change appetite to avoid possible poisons for fetus.
- Postural changes to compensate for anterior weight.
- Breasts enlarge--first milk production. (Frolich PowerPoint Slide 22)
(Insert Stages of Pregnancy picture / pregnancy.more4kids.info / http://pregnancy.more4kids.info/category/stages-of-pregnancy)
B. Birth:
- Uterus contracts throughout pregnancy.
- Braxton Hicks Contractions: False labor.
- Uterine contractions push fetus downwards, and cervix stretches.
- Parturition: Process of giving birth to an offspring.
- Loss of mucous plug, that during pregnancy, keeps out bacteria and other sperm.
1b. Stage 1: Contractions cause cervical canal to slowly disappear, and lower part of uterus is pulled up toward baby's head, = Effacement.
- Baby's head helps cervical dilation.
- Amniotic membrane ruptures.
2b. Stage 2: Contractions occur every 1-2 mins.
- Desire to push.
- Episiotomy: incision to enlarge opening of vagina, to allow for birth.
- Umbilical cord is cut and tied.
3b. Stage 3: Afterbirth: Placenta is delivered.
(Mader 369)
(Insert Process of Birth picture / Frolich PowerPoint Slide 23)
V. Development After Birth
A. Stages of life: Infancy, childhood, adolescence, and adulthood.
1a. Gerontology: Study of aging.
- Human life span maximum: 120-125 years.
2a. Hypotheses of Aging
- Genetic in Origin: Aging has genetic basis.
- Some genes decrease life span. When inactive, the mitochondria do not produce energy, and the cell uses alternative pathways. Defective mitochondria may produce more free radicals than usual. Caloric restriction can shut down the genes that decrease life span.
- Whole-Body Process: Decline in hormonal system can affect many different organs of body.
- Perhaps aging results from loss of hormonal activities and a decline in functions they control.
- Aging may be due to a specific type of tissue change that affects all organs and even the genes.
- Extrinsic Factors: Diet, exercise, cigarette smoking, heavy alcohol intake, inadequate calcium intake, etc.
B. Effect of Age on Body Systems:
1b. Skin: Skin becomes thinner and less elastic because the number of elastic fibers decreases and collagen fibers undergo cross-linking. = sagging and wrinkling.
2b. Processing and Transporting:
- Cardiovascular disorders are leading cause of death today.
- Arteries become more rigid with time.
- Heart shrinks due to reduction in cardiac muscle cell size.
- Blood flow to liver and kidneys is reduced.
- Respiratory disorders.
- Loss of teeth.
3b. Integration and Coordination:
- Reaction time slows.
- Hearing, taste, and smell receptors need more stimulation.
- Lens of eyes do not accommodate as well as before.
- Loss of skeletal muscle mass.
- Decline of bone density.
- Weight gain.
4b. Reproductive System
- Females undergo menopause.
- Males undergo andropause.
(Mader 370-372)
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