SELF EVALUATION UNIT IV

 

www.eco-conception.fr/images

 

1.  What were the three aspects of the assignments I've submitted that I am most proud of?    The three aspects of this assignment that I am most proud of are the human evolution portion, the lab for the events of embryo development and the chapter regarding human population.

2.  What two aspects of my submitted assignments do I believe could have used some improvement?  The thing I think I could have improved on is the posting pictures because some got cut off and then there was the ones that I thought were one thing and they posted as another. 

3.  What do I believe my overall grade should be for this unit?    Again, I think the overall grade should reflect my work and  I believe that I put a lot time and effort into all my work.

4.  How could I perform better in the next unit?  Ahhh, no other unit to do!!  All of the units were a challenge.

 

 

At what moment during this unit did you feel most engaged with the course?  I felt most engaged with the reproduction part of this unit.  Even though you as an individual think you know your body; you learn something new.

At what moment unit did you feel most distanced from the course?  I wasn't really interested in the evolution, but to my surprise it was very interesting.

What action that anyone (teacher or student) took during this unit that find most affirming and helpful?  I was frustrated with the demographic lab, but you helped by answering my emails!!!  Also, a student took the time to answer on ning. 

What action that anyone (teacher or student) took during this unit did you find most puzzling or confusing?  I didn't find anything puzzling or confusing.

What about this unit surprised you the most? (This could be something about your own reactions to the course, something that someone did, or anything else that occurs     When I was having a problem with the simulator, I was so happy that I finally figured out what was happening and finished the lab for the unit!!!

ETHICAL ISSUE UNIT IV HUMAN CONSUMPTION & FERTILITY

mrbarlow.wordpress.com

 

The article for this assignment was enlightening.  I don't think people actually "think" about how we as individuals consume energy.  I really never thought of it that way.   Also, our energy consumption in contrast to fertility.  I guess you could say the more production of humans involves more energy consumption.   When I think of third world countries, I think of their fertility rate because in some countries it is out of control.

  www.nextdaysite.net

These images of the children above are scary.  I think that some third world countries need education for birth control.  Even though, in the article for this assignment stated that Americans are the biggest energy consumers, there is something to be said for these countries because they don't have the resources to feed the children.  I think this whole thing about energy consumption and how it is being used is a viscous cycle.  There are thousands suffering.  There are a lot of proposals coming out on how we need to conserve, go green, and make better choices.  Is it too late??!!  I don't think so.  I think that we can pitch in and try and do our best to conserve energy.  The article for this assignment was a lot more in depth, but when I think of energy conservation I think of ways I, my self and my family can do our part.  I think that is where it has to start.  Each person doing their own thing to conserve.  As for the third world countries and the less fortunate, they need education on how things work; how they as individuals consume energy.  I think education is key to energy conservation!   I am sure that there is no "one" real solution, but one at a time, these solutions can be tested and maybe even perfected.

 www.reliant.com

The human population, on a molecular level, consume energy?!!!  Surprising, because we are made up of chemicals; these chemicals interact with other chemicals.  Another amazing piece of information.    I really think we, as a country are moving in the right direction when it comes to resolve for poor energy use and fertility.    Nothing happens over night, but in time things will change little by little and every little bit makes a difference.

HUMAN POPULATION DEMOGRAPHIC LAB

HUMAN POPULATION DEMOGRAPHICS LAB WRITE-UP
This is the simulator you'll use for your lab write-up.  It's a simple, but very powerful, way to see how population change depends on current population age distribution, along with reproductive and death rates.  Your book also has a very good section on demographics.
The key to using the simulator is to open the "Options" button for each population comparison box.  Select the first pull-down option under "Options" "Select Region/Country for Simulation."   This will open a world map where you can select a particular country or region of the world and see its current population structure and then simulate its future population growth based on current statistics.  PLEASE DO THE FOLLOWING:
1.  Choose the entire World for the upper simulation.  Run the simulation out to the year 2050 (as far as it goes).
2.  Now choose a country for the lower simulation that has a much lower fertility rate than the entire world.  Note if the initial population structure is different, and how.  Then run the simulation out to year 2050.
3.  Grab this screen shot and save it to post to your blog.
4.  Repeat the same steps, but for a region or country with a much higher fertility rate than the entire world.
FOR YOUR WRITE-UP:
Post the two screen shots:  one should have the world simulation compared with a lower fertility rate country or region; one should have the world simulation compared with a higher fertility rate country or region.
Answer the following questions:
1.  What was your high fertility rate country and what was its fertility rate?

I choose Afghanistan with the high fertility of 6.4.

 

 

 

2.  What was your low fertility rate country and what was its fertility rate?

I choose Taiwan for the low fertility.  It shows that it on the decline.  The fertility number was 1.8.

 

 

 

 

 

3.  The initial demographic "shape" of your high fertility rate country should have been a pyramid, with high population in young age groups.  Explain why high fertility rate results in a high percentage of young people in the population.  How does this affect future population growth?  It does show the decline of the older population.  Maybe in this particular country people can not seek health care because they can not afford it.  Also, on the up swing of that the younger population is growing because of no birth control.
4.  Your low fertility rate country might have had a more oval-shaped curve with high population in middle age groups.  This is especially exaggerated if the fertility rate is below 2.00.  Explain why low fertility rate leads to lots of middle-aged people.  I believe this leads to higher middle aged people because it could be due to malnutrition of the children, no proper prenatal care, and poverty.
5.  Write ten adjectives or descriptive phrases for what you might expect life, people's attitudes, conditions on the streets, etc. will be like in each of those situations.  Imagine a situation with lots of middle-aged and older people in the population and write ten quick "brain-storm" descriptors for you think it would be like (Prescott, Arizona?).  Then do the same for a situation with lots of children in the population.    I think a lot of areas are becoming just middle aged or elderly because of retirement places to live.  The way the economy is going I believe less people are having children and the area you live in does make a difference.  Some people may be living in poverty while others are just making ends meet.   I think Prescott, Arizona is a retirement community because of the mild winters.  This will lead to higher elderly and less children.  When people are raising children they want to live in a community that has children their kids age.   Its an interesting world we live in and is amazing how the countries differ in population.
To get full credit for this lab (20 points), you just have to post the two screen shots and answer all the questions.

COMPENDIUM IV HUMAN EVOLUTION & ECOLOGY, GLOBAL ECOLOGY, HUMAN POPULATION

WWW.chnm.gmu.edu

HUMAN EVOLUTION & ECOLOGY

a.  origin of life

b.  biological evolution/natural selection

c.  classifications of humans/primates

d.  evolution of humans

I want to start with a definition of evolution.  Evolution is the descent of organisms from common ancestors with the development of genetic and phenotypic  changes over time that make them more suited to the environment.  Wow, what a definition, but it makes sense.  We all come from somewhere and with a certain ancestor history.   Think way back when dinosaurs were roaming the earth instead of humans.  What ancestors did they have?  Who are our ancestors?    In the book they start with the origin of life and that all life consists of cells coming from preexisting cells, but how did the first cell come about?  Great question!  It is said that the earth along with the sun and planets were created millions of year ago from dust particles and debris.   It is said that the earth's mass is a gravitational field is strong enough to have an atmosphere.  Atmosphere is gaseous envelop surrounding the earth; the air.   If there were less mass the atmospheric gases would escape into outer space.  Obviously the atmosphere millions of years ago was much different then it is today.  The atmosphere back then was formed by gases from volcanoes.  If that was the case then the atmosphere had water vapor that consisted of nitrogen and carbon dioxide, with small amounts of hydrogen and carbon monoxide.    There was very little oxygen in the atmosphere.  Because of the rain the volcanic molecules washed into the oceans.  Primitive earth had many sources of energy besides volcanoes  there were meteorites, radioactive isotopes, lightening and ultraviolet radiation.   All these energy may have mixed together and reacted with one another and produced small organic compounds, such as nucleotides and amino acids.   Scientists have conducted experiments with gases from the earth's atmosphere and when heated and circulated it past an electric spark.   When this stuff cooled it was discovered that there was a variety of organic molecules.   These organic molecules joined to become macromolecules, which is larger molecules.   There were two hypothesis concerning the macromolecules in the origin of life.  First there was the RNA-first hypothesis, which suggests that only the macromolecule needed at this time to progress toward formation of the first cells.   The hypothesis went on to prove that RNA could be either a substrate or an enzyme during RNA processing.  RNA enzymes are known as ribosome's, which produce protein synthesis and are composed of ribosomal RNA.  It was thought that RNA could carry out what DNA does today.  The second hypothesis is the protein-first hypothesis.  With this hypothesis it showed that amino acids join together when exposed to heat.  A scientist thought that the amino acids on rocky shores, when heated by the sun caused them to form proteinoids, which are small polypeptides that have some catalytic properties.  If the proteinoids return to water they form microspheres which are structures composed only of proteins that have many of the properties of a cell.    The protocell, in biological evolution, is a possible cell forerunner that became a cell once it could reproduce.  A cell has a lipid protein membrane and if the lipid and microspheres came together it could possibly produce the lipid protein membrane.    A true cell is one that can reproduce.   The true cell is what we think of in today's cell, with the DNA replication before cell division.  This is a picture of a cell as we know it..........

www.animalport.com

I guess in order to become a true cell (one that reproduces) scientists needed to do some research.   This comes back to the RNA-first hypothesis and the proposed steps.  With this hypothesis the first cell had RNA genes that, similar to the messenger RNA ,could have specified protein synthesis.  Some of the proteins were enzymes and maybe one of these enzymes like; reverse transcriptase could use RNA as a template to make DNA.  Replication of DNA would then take place normally, like we know it.  But the other hypothesis; protein-first, suggested that some of the proteins in the protocell would have evolved the enzymatic ability to synthesize DNA from nucleotides in the ocean.   Then the DNA would have gone on to specify protein synthesis, and in this way, the cell could have acquired all its enzymes even the ones that replicate DNA. 

BIOLOGICAL EVOLUTION

It was believed that the first true cell was the prokaryotic cell because they lacked a nucleus and most organelles.   Then eukaryotic cells evolved and they do contain a nucleus.  Also, there were other multicellular and other kingdoms that evolved such as; fungi, plants and animals.   Biological evolution is the processes by which a species changes through time.  This is a great example of how we as humans evolved and where we came from.  There are two important aspects of biological evolution and one of those is common ancestor and secondly, is adaptation to an environment.   Our descent relates to our common chemistry and cellular structure.  Adaptation relates to being able to survive and reproduce in a different environment form your own.  Humans are great at adaptation because we can move around and adapt to almost anywhere.    Adaptation also helps explain the diversity of life and why there are so many different types of living things.  Charles Darwin is basically the founder of evolution.  He traveled extensively through the tropics where life-forms are more abundant then in other areas.  He discovered that life forms change over time and from place to place.   The first discovery were fossils,  Fossils are evidence of an organism that has been preserved in the earth's crest or through sediment over a long period of time.   It is said that fossils are the greatest evidence that there was life millions of years ago.  This evidence includes footprints, burrows, trails and even preserved droppings.   There are also bone fossils, like the bones of dinosaurs.  Some fossils can be imprints of plants from long ago and even insects imprinted in trees from getting caught in the resin.  Most fossils though are found in rock because of the sediment changing over time.   Weather plays a key roll in sediment because of the rain washing things away or water rising can cause sediment.   Darwin showed evidence of common descent through the hypothesis.  The explanation for anatomical similarities among organisms.  One example is a bird and a bat that have similar structure in their vertebrate forelimbs used for flight.  Another example is whales and seals for swimming.  A horse for running.

www.colorado.edu

In this picture you can see the similarities in the bones structure and function.   Structures that are anatomically similar because they are inherited from a common ancestor are called homologous structures.   Analogous structures serve the same function, but they are not constructed the same and they don't have a common ancestor.   There are also vestigial structures and these are anatomical features that are fully developed in on group of organisms, but are reduced and may have no function in similar groups.  An example of this is the whale and they have a vestigial pelvic girdle and legs, but their ancestors walked on land.  Whales swim!  Another example could be birds because some birds have wings for flight and others have wings that don't fly.  Biochemical evidence shows that almost all living organisms share the same molecular structures.   Scientists have done extensive research on DNA, not only on humans, different species and they found that humans share a large of genes with similar organisms. 

NATURAL SELECTION

Natural selection is the mechanism resulting in adaptation to the environment.   Darwin, again, discovered natural selection while he spent time in the Galapagos Island and studied finches that resembled on another but had different ways of life.   He discovered that some of the finches were ground seed feeders, insect feeders, and ground cactus eaters.   Because of these differences Darwin believed that these finches were all descended from a mainland ancestor whose offspring had spread out to other islands and adapted to the different environments.   Another naturalist, Jean-Baptiste Lamarck had an explanation why giraffes long neck were based on the assumptions that the ancestors of modern giraffe were trying to reach into the trees to browse on high growing vegetation and that continual stretching of the neck made the giraffes neck to become longer.  Then this characteristic was passed to the next generation.  Lammarck's theory for this characteristic would not work because characteristics are not inherited.    Here is a picture of the giraffe that Lammarck was referring to.

www.img.sparknotes.com

There are three critical elements of natural selection; (1) variation:  this is when members of a species have similar physical characteristics and these can be passed from generation to generation.  (2) competition for limited resources; each individual could produce many descendents, the number in each generation usually stays the same.  This is because resources are limited and competition for resources results in unequal reproduction among the population.  (3) adaptation is when the population has advantageous traits can capture more resources and are more likely to reproduce and pass their traits and the environment "selects" for the better adapted traits.  Besides birds and Darwin humans have a great natural selection because we adapt easily to different environments.  Maybe not in other countries; it may take a little longer to adapt, but it would happen.    Here is a description of the classifications and evolution of humans; one that is not listed and what human are and is the domain -eukaryotic and is membrane bound nucleus.

www.teara.govt.nz

Humans are primates.  Primates have mobile limbs, grasping hands, flattened face, binocular vision, large brains, and a reduced reproductive rate.   There are two suborders to primates.  One is prosimians and this includes the lemurs, tarsiers and lories.  The second is the anthropoids and this includes monkeys, apes, and humans.   We know that humans are closely related to monkeys and apes. 

EVOLUTION OF HUMANS/HOMINIDS

 www.daviddarling.info/images/primate

This picture represents the family tree of primates and how humans have evolved.   Hominids is a term that refers to the branch of the evolutionary tree that you see above.  Any fossil that is placed in the hominid tree of descent is closer to human than to on of the African apes.  the features of a hominid determined by the paleontologists who dig for fossils in remote areas.   One of the features is bipedal posture, which refers to walking on two feet.  Some of the hominid even lived in trees.  These hominids may have have four limbs, but they only used the hind legs to walk.  Two other important features of hominids are the face and the brain size.  Humans today have a more flattened face as where the chimpanzees it is more pronounced.  The brain size of humans is also larger then the chimpanzees.   Here is a picture of human evolution that explains the different species; these are more modern human evolution.

Fossils are assigned to HOMO if (1) the brain size is 600cm3 or greater (2) the jaw and teeth resemble those of humans and (3)tool use is evident.   Early homos date back to 2.0 and 1.9 millions of years ago and may be ancestral to modern humans.  They have found fossils with brain that are as large as 775 cm3.  They also say that the early homos  are members of the omnivores, who ate meat and plants.  Another example of homos class is the homo erectus and these are usually found in Africa, Asia, and Europe.   Eugene Dubois was the first to find H. erectus bones in Java in 1891 and since his discovery there have been many more found in the same area.  There is a similar species found in Asia called the H. ergaster and these species had a very large brain and a protruding nose, in which it says that the nose protruded because these species lived in hot climates and permits water to be removed before air leaves the body.  Our species is considered homo sapiens and it is believed that we evolved from homo erectus, but differ as to the details.   It is also believed that homo sapiens evolved in a multitude of areas and this is just a hypothesis.  The neandertals (H. meandertalensis) had a huge brow ridges, and their nose, jaw, and teeth protrude far forward.   You can see those features in the picture above.   The neanderthal also had a slightly larger brain then homo sapiens and the were larger in the shoulder and chest area.  It was believed (hypothesized)that their brains were larger to deal with the extra muscular structure.    They lived in caves or may have built homes, but for the most part they lived in caves.  They  made homemade tools out of stone, including spears points.  The neanderthals probably ate bears, wooly mammoths (look like elephants), and reindeer.  They made fire to cook these catches and to keep themselves warm.  Next, is the cro-magnons and these are the oldest fossils to be designated homo sapiens.  These fossils were discovered in France.   The cro-magnon also made tools out of stone; spears that they could throw from a distance to kill their prey and not be hurt.  It is believed they were the first to do spear hunting.  They were accomplished hunters who may be responsible for some extinction of certain large mammals.    They also use to draw art on the cave walls using reindeer antlers and bones.

GLOBAL ECOLOGY

a.  ecosystems

b.  energy flow

c.  water cycle

d.  carbon cycle

e.  nitrogen cycle

f.  phosphate cycle

Ecosystems differ in that there are different kinds.  There is aquatic or terrestrial just for an example.  An ecosystem is defined as a biological community together with the associated abiotic environment characterized by energy flow and chemical cycling.   Also, an ecosystem can vary in size, from the Sahara desert to a puddle, ecosystems are dynamic interactions between plants, animals and micro organisms and their environment working together as a whole. If ecosystems do not remain in balance then it is likely that they will fail.   the terrestrial ecosystems is also known as the biomes.  Temperature and rainfall define the biomes and these areas contain communities of organisms and they are adapted to the climate.  There are many biomes; the rain forest is a great example because of all the lush tropical trees and a variety of organisms.

www.puertogalera.rainforest.googlepages.com

This is a picture of the rain forest.  Another example of an ecosystem is an aquatic ecosystem and this deals mainly with  water.   This could be the ocean floor to a river in Rhode Island.  There are two components that are involved in an ecosystem and one is the abiotic component that are nonliving and the biotic component that are living things that can be categorized according to their food source.  Also there are different populations or species one is autotrophs which require inorganic nutrients and outside energy source to produce organic nutrients for their own use.  They are also considered producers because they produce food.   Another population is heterotrophs and they need organic nutrients and they are considered consumers because they "consume" food.  Herbivores are animals that eat only vegetation like plants or algae.   Insects are considered herbivores in the rain forest.  Carnivores eat other animals like birds or a hawk that eats rabbits is a good example.   Then there are omnivores which feed on animals and plants and a great example of an omnivores is humans. 

ENERGY FLOW....................

www.bcgrasslands.org

This picture represents how the energy flows through an ecosystem.    There is also chemical cycling.  The sun starts the process of energy flow.  The producers absorb the solar energy and chemical cycling begins when the producers take in the inorganic nutrients from the physical environment.  Then through photosynthesis the producers make organic nutrients (food) for themselves and for the other populations of the ecosystem.  The energy flow occurs because as the nutrients pass from one population to another all the energy is converted to heat and then dissipates into the environment.    All the autotrophs,heterotrophs, carnivores, and others benefit from the energy flow within an ecosystem.

THE WATER CYCLE

www.carrier.pbwiki.com

This picture represents the water cycle within an ecosystem.   With evaporation, the suns heat makes the freshwater to evaporate.  Within the ocean the freshwater evaporates and leaves behind extra salt.   During condensation a gas is changed to a liquid.  the freshwater that has evaporated will then vaporize and from the vaporization the freshwater rises into the atmosphere, condenses and falls as precipitation (rain,snow).   Land is above sea level, so when it does precipitate the runoff will flow back into the ocean and lakes.  Some of the precipitation penetrates into the ground and this is called the water table or ground water table.

THE CARBON CYCLE

WWW.ecosys.cfl.scf.rncan.gc

This picture represents the carbon cycle with an ecosystem.  The terrestrial and aquatic ecosystems are involved in the carbon cycle.  There is exchange of carbon dioxide within the atmosphere; on  land plants take up the carbon dioxide from the air, and through photosynthesis and then they incorporate carbon into nutrients that are used by autotrophs and heterotrophs.   In the aquatic ecosystem the carbon dioxide is an indirect exchange.  The carbon dioxide mixes with the air to produce bicarbonate ion which is a source of carbon for algae that produce food for themselves and for heterotrophs.   Living and dead organisms contain organic carbon and serve as one of the reservoirs for the carbon cycle.   There is also transfer of carbon with our cellular respiration (breathing), and photsynthesis and includes the work of decomposers.   With the carbon exchange this also produces green houses gases and global warming!  This is a major concern for our planet.  By trying to reduce these gases we all can help save the planet for the future.  Everyone is "going green"!!!  The global warming is due to human activities and how we treat our plant and if everyone does their part we can prolong this.

THE NITROGEN CYCLE

www.scienceprogress.org

This picture represent the nitrogen cycle.  Nitrogen is also a gas that is exchanged with the atmosphere.  Nitrogen can cause limited growth within plants.   In the nitrogen cycle, nitrogen fixation occurs and produces ammonium and the plants can use this form of nitrogen.  Plants can also use nitrates which is another form of nitrogen.   The change of the nitrogen into nitrates is called nitrification.   Human activities also change the transfer rate in the nitrogen cycle by producing fertilizers.  Fertilizer contains phosphate and the runoff into lakes and rivers can result in an overgrowth of algae and aquatic plants.  This overgrowth can lead to an algal boom and with this when the algae finally die off the decomposers use up all the oxygen in the lake or river and this kills all the fish.

THE PHOSPHATE CYCLE

WWW.filebox.vt.edu

This picture represents the phosphate cycle.  With the phosphate cycle, if the oceans sediment is up heavaled the phosphate is released. When on land the phosphate transfers into the soil and becomes available to plants.  If the plants do not get phosphate it is hard for them to reproduce and it makes the population low within the ecosystem.  The phosphate that is on land can runoff into the aquatic ecosystem and the algae takes it up before it is transferred to the sediment.

HUMAN POPULATION

a.  mdc's versus ldc's

b.  human use of resources and pollution

c.  biodiversity

 

www.census.gov

We all know that our population is constantly on the rise.    The growth rate is determined by the number of births and the number of deaths per year.     The birth rate is higher then the death rate.   People are living longer these days, with all the advance technology.    The country can be divided into two groups.  One is the MDC's (more developed countries) and LDC (less-developed countries).  The MDC's have a modest growth rate and have a good standard of living.  The LDC's which can include Asia, Africa and Latin America are those in which the population growth is dramatic and the majority of people live in poverty.   The MDC's having a steady rate growth changed in 1850 thru 1950 because of the death rate decreased due to the discovery of modern medicines.   The LDC's death rate also began to decline due to modern medicine, but the birth rate stayed high.  People in the LDC lack proper birth control because most cannot afford the prescribed contraceptives or don't take the proper precautions.   The LDC population will jump from 5 million to 8 million and some of this increase will be in Africa, but most will be in Asia because of the AIDS that has spread through Africa making the death rate very high. 

HUMANS USE OF RESOURCES AND POLLUTION

There are many factors of resources that humans use in order to survive.  As for pollution, humans using cars for transportation and factories releasing gases are polluting the earth.  There are solutions for these problems, but people have to change their way living.  We can drive more efficient cars, ride a bike, or take the bus to work.  Some people even car pool.  Its all about choice and wanting to keep our planet!!   The four resources that humans are using are land, water, food, energy and minerals.   Land is obviously used for a place to live.  Farmers use land to grow their crops, power plants, highways for transport, hospitals. and the list goes on and on.  As the population grows, so does the need for more of the things that I just mentioned.   Beaches are a great example of where people are building their houses.  These houses are in jeopardy because of all the beach erosion and terrible storms along the coast.  It also effects the habitat for marine organisms.

www.calstatela.edu

Another place that is effected by humans is the rainforest.  They are cutting down the trees!!!   The soil in the rainforest is thin and nutrient poor because all of the nutrients are taken up by the forest itself.  If the trees are taken and the land used for agriculture it loses its fertility and becomes subject to desertification (the conversion of semiarid land to desert like conditions).    This picture below is a great example of desertification...........

www.giftedkidsnetwork.com

As you can see these fish lost their natural habitat due to desertification.    Water is another resources that humans abuse.  Worldwide, 70% of the water supply is used to irrigate crops.  But we need crops for food.  This is a vicious cycle and we need solutions!    The MDC's use the most water and it is used for bathing, flushing toilets, and water lawns instead of drinking and cooking.  I think that should be the opposite, but the MDC's are domesticated and it goes through generation to generation.  Modern conveniences is what the problem is.   To help with increase demand of water we have created dams.  Dams are controlling the water in reservoirs or aquifers.    Ground water is also a factor when it comes to water.  Some states have severe droughts and these droughts can ruin crops.    The aquifers hold rainwater and this accumulates.  The ground water is depleting and has become a problem in many areas of the world.  One example is the high plain aquifer, which stretches from South Dakota to the Texas panhandle and more then half the water has already been pumped out.  Food is a resource that we as humans cannot live without!    We could eat more vegetables instead of meat.    We get our food from three main sources; crops, raising animals, and fishing.   These three resources are on the rise as population grows.   With producing crops, some of the chemicals they use can be harmful and they use a generous amount of irrigation.  If all the people that produce crops were organic that would be one resolve for the chemicals.     The chemicals they use can also ruin the soil that they are planting in.    Another solution is intercropping, which is planting two or more different crops in the same area.  An example is planting alfalfa between strips of corn.  The alfalfa replenishes the nitrogen content of the soil so that fertilizer doesn't have to be added.   What a great solution; why isn't everyone doing this??!!!     With livestock, these animals start out eating natural stuff and then they are stuffed in feedlots and feed grain, while being pumped with growth hormones and antibiotics.  This is outraging!  By placing these animals so tightly packed in feedlots contamination can occur, besides other things.  Now onto energy!  Here is where we could save a lot.  Humans surely abuse energy.  There are a lot of new alternatives that people are coming up with to save energy.    One example is the hydropower.  They have created hydroelectric plants that convert the energy of falling water into electricity.  Here is a little picture that shows how this energy is produced.............................

www.earthsci.org

We also have the Hoover Dam which is not that far away from where I live in Arizona.  

www.aboutmyplanet.com

Another way energy is being produced is the wind power.    These are becoming very popular.  It was thought that they would use a lot of land but compared to the coal-fired power plants the wind power is much more favorable. 

www.fluorescentefficiency.com

This is a picture of what is used for the wind power.   These turn wind into energy!!  Kind of amazing if you think about it.   Communities could generate their own electricity by using these and solve the problem of uneven energy production by selling electricity to a local public utility when an excess is available and buying when the wind power is in short supply. 

BIODIVERSITY

www.environment.go.ke

Biodiversity can be defined as the variety of life on earth.  This picture is just a small portion of what is on earth.    There are major causes of biodiversity loss and extinction.   Humans, again have a hand in the habitat loss in biodiversity.  Due to the increase in houses across the coastline, cutting down trees in the rainforest, and semiarid lands being destroyed.   One major concern is the rain forest and the coral reefs in the ocean because these area are abundant in different species.   The coral reefs are explored by thousand of tourist that contribute to the destruction.  They say that there may be no more coral reefs in another forty years.    There are also alien species that humans are creating and bringing into certain areas that really don't produce them.    Some alien species can become invasive, meaning that they take over the native plants to the area.   Pollution is a major concern to the biodiversity because it brings about environmental change that adversely affects the lives and health of living things.   Biodiversity is mainly affected with the acid deposition which decimates forest because it causes trees to weaken and increases their susceptibility to disease and insects.  Another form is global warming.  This term, global warming" is becoming more and more common because people are trying to save our plant from this fast growing melt down.   This is a increase in the earth's temperature due to the presence of greenhouse gases in the atmosphere and it has many detrimental effects. 

www.aolcdn.com

This picture represents the greenhouse gases that are being released into our atmosphere.  There are also coastal effects.  The polar bears are in great danger of losing their habitat due to global warming.

www.alaska-in-pictures.com

Obviously, this polar bear should be standing on ice, not bare land.   Overexploitation is a concern for any species that are unique.   Humans hunt certain animals for their coat and if these animals are taken by large numbers then the population will decrease making it harder to reproduce.    There is also illegal trade of certain animals and even plants.  These people go into the wild and capture wild parakeets to then be sold.  It seems like it is all about profit; not for the good of humankind!!  This really has to stop if we want our plant to beautiful and safe to live in.    Fishermen go out in these big boats to catch a large amount of fish not only to sell to the market, but put food on their table too.  The government has put restrictions on these big boats, making it so they can only fish on certain day and for so many days.   The reason they are doing it is because they are trying to preserve the food supply and the food web of the ecosystem.  Some fisherman don't understand that because on those certain days that they are allowed out to fish the weather might be awful and they can't go out.    There are species that are a direct value of biodiversity.  One example is the rosy periwinkle, that has provided useful medicines.  There are certain chemicals in this plant that are known to be used in the treatment of cancer.  Also, because of this plant survival of childhood leukemia has gone from 10% to 90% .   There are a lot of amazing things in this world that scientists and others are exploring to make our plant better and making people better.  Research is a wonderful thing!!   We all can do our part to go green!!!!

test post

LAB IV: 10 EVENTS OF EMBRYONIC & FETAL DEVELOPMENT

 

STAGE 1 & 2:  After fertilization occurs, the zygote is produced.  The zygote is what becomes the embryo.  The zygote leaves the fallopian tube and enters the uterus.

 

As you an see in the picture above the zygote is traveling to the uterus for implantation.  The process of the fertilization happens 1 day post ovulation and the zygote process occurs 1 to 3 day post  ovulation.  Both happen within the first trimester of pregnancy.

STAGE 4:  Implantation also takes place within the first trimester and 5-6 day post ovulation.  Implantation is significant because if it doesn't happen correctly then this could result in losing the baby.  The placenta also begins to develop in this stage.  This is very significant because  this is where the fetus gets its nourishment.

www.ehd.org

pic of implantation

STAGE 6:  Gastrulation begins, which is the migration of cells to the outer edges of the disc into the primitive streak and down creating a new third layer.  This occurs 13 days post ovulation.   The embryo now has three layers ectoderm,mesoderm,and endoderm which will develop into differently.  The ectoderm will develop into skin, hair, lens of the eyes, and many more things.  The mesoderm will develop into muscle, bones, lymphatic vessels, spleen, heart, and lungs.  The endoderm will develop into lining of the lungs, tongue tonsils, urethra, and GI tract.

STAGE 23:  I think this a significant event because this is the end of the first trimester and the embryo is now a fetus.  This occurs 56 -60 days post ovulation.   It looks like a baby inside the mother.  The had and neck are rounded, the ears are developed externally, intestines begin to migrate from the umbilical cord into the body cavity.  The limbs are developed and the fingers grow longer and the feet are not longer a tail or webbed.

STAGE (16 WEEKS) 2ND TRIMESTER:  This is significant because the bone marrow begins to make blood cells.  The fetus is moving around.  The brain develops rapidly and continues five years after birth.  Here is a 3-D picture of this stage.

www.goldenviewultrasound.com

STAGE (24 WEEKS AND 3RD TRIMESTER):  I think this stage is significant because the fetus eyes are sensitive to light and the ears are sensitive to sound!!  How cool!!!    Also, the significance of this stage the blood vessels start to develop in the lungs to prepare the fetus for living outside of the uterus.   Picture of another 3-D fetus at 24 weeks.

 

STAGE (32 WEEKS 3RD TRIMESTER):  The significance of the stage is that the fetus begins to develop an immune system, which is very important!!  What I think is neat is that the fetus eyes open during wake hours and close during sleep periods!!  Picture of 32 weeks (7 months).

STAGE (34 WEEKS,  3RD TRIMESTER):  This stage is significant because the fetus's GI system is very immature and it does not fully develop until 3-4 years after birth!! WOW!  Also, they have stored fat to keep them warm.

STAGE 38 WEEKS 3RD TRIMESTER):   This is significant because the liver is producing blood cells.  Also the fetus is gaining weight (1/2 ounce of fat).

www.pregnancyhut.com

STAGE (WEEKS 3RD TRIMESTER):  This is significant because this means the fetus has been carried full term.  I think this is very important because most of the development happens within the mother.  Premature babies can have a lot of complications.  When the fetus is born it has 300 bones!  This picture shows the 40th week and the mother should be ready to deliver any day.

www.kappamedical.com

Just another picture because I thought it was sooo cute!

There are so many stages of a pregnancy and it was hard choose what was more significant then others, but I think I narrowed it down.   

SORRY THAT DIDN'T WORK EITHER!

COMPENDIUM IV

ANOTHER PICTURE THAT DID NOT POST CORRECTLY.  THIS PICTURE IS TO REPLACE THE LITTLE GIRL STICKING HER TONGUE OUT.  SORRY!!

compendium IV pic of contraceptives

 

some of the pictures I choose for my compendium did not upload properly.  Trying again! 

UNIT IV COMPENDIUM REPRODUCTIVE SYSTEM & DEVELOPMENT WITH AGING

 

REPRODUCTIVE SYSTEM

a.  male reproductive system, orgasm & hormonal regulation

b.  female reproductive system, orgasm & Ovarian cycle

c.  female hormones relation to reproduction

d.  birth control and infertility

e.  sexually transmitted diseases

 

As you can see above, the reproductive system consists of our primary and secondary sex organs.  Mostly, the primary are responsible for reproducing another human being.  There are many steps into creating a human.  I will begin with the male reproductive system and what it consists of and their functions.  The primary sex organs a.k.a., gonads are the testicles, which are in a sac called the scrotum.  (You can see this in the picture above).   The vas deferens is the tube that connects with the urethra to release sperm.  The urethra also releases urine.   Sperm is produced in the testicles and they mature in the epididymis.  The epididymis is a tightly coiled duct that is outside of the each testicle.  The sperm need to mature so they can swim to the egg inside of the female.  Sperm leaves the epididymis and enters the vas deferens.  When ejaculation occurs sperm leaves the penis in a fluid called semen.  The seminal vesicles, prostate gland, and the bulbourethral glands add secretions to seminal fluid.  The seminal vesicles lie at the base of the bladder.  The prostate gland is a donut shaped gland that surrounds the upper portion of the urethra just below the bladder.  The prostate can enlarge in some males, making it difficult to urinate.    The bulbbourethral glands are pea-sized organs are under the prostate and their secretion helps make the seminal fluid more gelatinous.  Sperm needs energy to swim and the seminal fluid actually contains fructose, which is a sugar; this sugar give the sperm energy to swim.  The semen also contain a chemical, prostaglandin, that causes the female uterus to contract and some scientists believe that these contractions help propel the semen towards the egg for fertilization.    The penis is the male organ used during sexual intercourse.  It has a long shaft and the tip of the penis the called the glans penis.  The glans penis is usually covered with skin, but when a male baby is born, most couples decide to that extra skin removed.  This procedure is called a circumcision.  When a male has an orgasm the spongy erectile tissue containing distensible blood spaces extends through the shaft of the penis.  When a male is sexually aroused, autonomic nerves release nitric oxide and this stimulates the production of cGMP (cyclic guanosine monophosphate).  The cGMP causes the smooth muscle of incoming arterial walls to relax and the erectile tissue to fill with blood.   The veins that take blood away from the penis are compressed and the penis becomes erect.  Some men suffer erectile function (they cannot get a erection).   This happens when the erectile tissue doesn't expand enough to compress the veins.   The are medications for "ED" but one of the side effects is that it may cause blindness.  The medication itself inhibits the enzyme that breaks down cGMP to insure an erection.  Also, because urine and semen pass through the urethra, there is a sphincter (a opening) that closes off the bladder so that no urine enters the urethra.  Within the testicles there are seminiferous tubules and interstitial cells.    The testicles have compartments called lobules and each contain three tightly coiled seminiferous tubules and packed with cells undergoing spermatogenesis, which is the production of sperm.  During the production of sperm it goes through a process.  First spermatogonia divide to produce  primary spermatocytes that move away from the outer wall, increase in size, and undergoes meiosis II (nuclear division) to produce four spermatids, and contains 23 chromosomes.  Spermatids then differentiate into sperm.  It takes 74 days for sperm to undergo development from spermatogonia to sperm.    The sperm actually has three parts to it.  There is the head, tail and middle piece.  The head is what penetrates the egg in the female and contains a nucleus covered by a cap called the acrosome.

 

 

 

www.advancedfertility.com  (pic of microscopic sperm)

The acrosome stores enzymes needed to penetrate the egg.   The middle piece of the sperm contains mitochondria which gives the tail (flagellum) its movement.   Interstitial cells are hormone secreting cells located between the seminiferous tubules and the testes.  They are also known as the androgens.  One of the androgens is testosterone, this is the main sex hormone in males and is essential for the normal development and function of the reproductive organs in males.   Also, testosterone is responsible for males hair on their face, chest, and other regions of the body. Testosterone is responsible for the muscular development in males.  In hormonal regulation in males the hypothalamus controls the testes sexual function because it secretes a hormone, gonadotropin-releasing hormone (GnRH) and stimulates the anterior pituitary gland to secrete the GnRH.  There are two gonadotropic hormones; follicle stimulating hormone (FSH), and luteinizing hormone (LH).  Both male and female have these hormones, but with males FSH promotes the production of sperm in the seminiferous tubules.  LH in males controls the production of testosterone by the interstitial cells.   These hormones act in a negative feedback; meaning that when there is too much testosterone produces the hypothalamus sends a signal to the anterior pituitary to decrease the secretion.  

FEMALE REPRODUCTIVE SYSTEM

At the top of this compendium is a picture of the female reproduction system.   The female gonads are the ovaries that lies in a shallow depressions one on each side of the pelvic cavity.  The ovaries produce eggs and the female sex hormones; estrogen and progesterone.   The oviducts also known to many as the fallopian tubes extend from the ovaries, but are not attached.  They have finger like projections called fimbriae which helps sweep the egg into the oviduct.  When egg enters the oviduct it is propelled by cilia and muscle contraction toward the uterus.   The lives only 6-24 hours unless fertilization occurs.  If fertilization does occur then a zygote (baby) is formed.  With fertilization, the egg and sperm meet and the sperm penetrates the egg breaking off its head inside the egg.  A developing embryo arrives at the uterus after several days and then is implanted in the uterine lining.  The uterus is a thick walled muscular organ  it lies above and is tipped over the urinary bladder.  The oviducts join the uterus at its upper end and the lower end the cervix enter the vagina.  During sexual intercourse the vagina is the opening that receives the penis.  It also  serves as the birth canal and for menstrual flow.  The embryo develops takes place in the uterus.  The uterus is sometimes referred to as the womb.  The uterus is capable of stretching over 30 cm wide to support the growing fetus.  The lining of the uterus is called the endometrium and participates in the formation of the placenta, which helps nourish the growing fetus.  The endometrium is also involved in the menstrual cycle in females.  If a woman does not get pregnant, the the cells sloth off the endometrium.   The female has external parts to their vagina.  One is the vulva, which includes two large hair covered folds of skin called the labia majora.  Secondly is the labia minora and it also has two small folds and lies inside of the labia majora.  When a women has a orgasm the labia minora, the vaginal wall, and the clitoris (external part) become filled with blood.  The vagina expands and elongates.  The blood vessels in the vaginal wall release small droplet of fluid that seep into the vagina for lubrication.  This lubrication allows the penis to enter easily.   The ovarian cycle occurs on a monthly basis.  The ovary contains many follicles and each one contains an immature egg called a oocyte.  A female is born with millions of follicles, but they are reduced by puberty. 

www.bioweb.wku.edu

This picture above gives you a little idea of the ovarian cycle.   It goes in a circle.  The female produces one egg a month.  When the follicle matures during the ovarian cycle it changes from a primary to a secondary to a vesicular (Graafian) follicle. The ovarian cycle is a series of events in the ovaries that occur during and after the maturation of the oocyte (egg or ovum). During the female reproductive years, non-pregnant females usually experience a cyclical sequence of changes in their ovaries and uterus. Each cycle takes about one month and involves both oogenesis, the process of formation and development of oocyte, and preparation of the uterus to receive a fertilized ovum.  The primary oocyte undergoes meiosis I (Nuclear division), and the resulting cells are haploid with 23 chromosomes.  Similar to the males sperm.  One of the cells that are produced is called a polar body and it acts as a trash can because it holds chromosomes that have been discarded.  The secondary oocyte undergoes meiosis II (nuclear division) but only if it is first fertilized by a sperm cell.  If it remains unfertilized it will never complete meiosis and it will die.   Ovulation takes place when the vesicular follicle burst and releases the egg (oocyte) covered with a clear membrane.  When the egg loses its vesicular follicle it develops into a corpus luteum; if the egg is not fertilized the corpus luteum disintegrates.  Also, the corpus luteum produces progesterone.   The hypothalamus has control over a women's ovaries just as it does the male testes.   It controls the sexual function and release GnRH (gonadtropin-releasing hormone) and they stimulate the pituitary  to produce FSH and LH.  The follicle stimulating hormone (FSH) and the luteinizing hormone (LH) control the ovarian cycle.  In the first half of the follicular phase FSH promotes the development of follicles that secrete estrogen.  When the estrogen levels increase, it sends a message to the anterior pituitary  secretion of FSH so that the follicular phase comes to an end.  The positive feedback effect has estrogen spike causes a sudden secretion of a large amount of GnRH from the hypothalamus.  Then, LH production by the pituitary and to ovulation at about the 14th day of a 28 day cycle.    The luteal phase begins and this is when the LH promotes the development of the corpus luteum, and this secretes progesterone. 

FEMALE  HORMONES WITH RELATION TO REPRODUCTION

The primary hormones in females are estrogen and progesterone.  They are not only involved in the process of the menstruation, but for example estrogen is responsible for the females secondary sexual characteristics.  These characteristics are body hair and fat distribution.  Females carry more fat then males.  Progesterone and estrogen play a role in another sex characteristics and that is breast development.    When a woman goes through menopause they don't menstruate as often (becomes irregular), and their estrogen and progesterone are no longer secreted.  The ovaries are no longer responsive to gonadotropic hormones produced by the pituitary.   There are hormone replacement drugs that woman can take, but studies show that when taken over a period of time it could cause cancer, heart attack and stroke.    Estrogen and progesterone play another role; the uterine cycle.  This is when menstruation occurs.  During the first and fifth day a low level estrogen and progesterone in the body causes the endometrium to disintegrate and its blood vessels to rupture, causing the female to bleed.  this blood and tissue known as the menses (period).  During days 6 thru 13 increased production of estrogen by a new ovarian follicle in the ovary causes the endometrium to thicken and become vascular and glandular.  This is call the proliferative phase of the uterine cycle..  On day 14 ovulation usually occurs.  Days 15 thru 28 there is an increase in progesterone by the corpus luteum in the ovary causes the endometrium of the uterus to double or triple in thickness and the uterine glands to mature producing a thick mucoid secretion.  This cycle last 28 days.  If a women has unprotected sex and could become pregnant.   When the male ejaculates in the female, his sperm try to make its way to the oviduct where the egg is located for fertilization.  Only one sperm can fertilize an egg and when it does the egg/sperm becomes a zygote.  then it travels to the uterus where it will attach itself to the endometrium and begin to grow into an embryo.  the embryo is nourished by the placenta that is developed for the maternal and the fetal tissues.  The placenta produces human chorionic gonadotropin (HCG) which maintain the corpus luteum in the ovary.  The HCG shows up in the females urine and blood; so if these tests are performed at a lab it shows that she is pregnant.  As the HCG levels rise to stimulate the corpus luteum to produce increasing amounts of progesterone. and this progesterone shuts down the hypothalamus and the anterior pituitary so that no new follicle begin in the ovary.  The progesterone is now responsible to maintain the uterine lining where the embryo. 

BIRTH CONTROL AND INFERTILITY

The are a number of contraceptives that couples can use to protect against pregnancy and sexually transmitted diseases.  The birth control for females is one contraceptive whereas the female has to take a pill daily.  These pills contain estrogen and progesterone.  There are also placebo pills and these are just a reminder that you need to take all the pill in the pack!  These pills work by supplying the body with the sex hormones for a large part of the cycle.  They inhibit the hypothalamus and the anterior pituitary so no new follicle begin in the ovary and ovulation does not occur.  Other forms of contraceptive are an IUD (intrauterine device) and this is placed inside the female.

www.en.wikipedia.org

This picture above is the IUD.

www.healthofchildren.com

This picture above shows different forms of contraceptives.  The birth control pill is in that round case.  There is a condom that the male has to put on his penis before intercourse.  A diaphragm is also another device that is inserted into the female and it is fitted by a physician.  With the diaphragm a spermicide jelly is also used for added protection.  These contraceptives are not 100% effective.   There are also procedure that both sexes can do that should be 100% effective.  The female could have a tubal ligation and this is when the tie the females fallopian tubes.  The male can undergo a vasectomy and this is when the vas deferens are cut on each side so that the sperm are unable to reach the seminal fluid that is ejected at the time of orgasm.   There is a new pill called the morning after, and this is when the female takes two pills after a night of sexual intercourse because she thinks she might get pregnant and then two more pills 12 hours later.   Some people protect themselves from getting regnant, but there are others who try and con not get pregnant.  This is called infertility and there are different reasons why this occurs.  It can be due to the female or male.  With the males the most common reason for infertility is their sperm count is low or the sperm are abnormal due to environmental influences.    It is said that smoking and alcohol consumption is most often the cause of infertility.    Also, if males have a job that requires them to sit for long periods of time the testes temperature remains too high for adequate sperm production.  The most come cause of female infertility is being overweight.  In a normal size female, fat cells produce a hormone call leptin that stimulates the hypothalamus to release GnRH.  In the overweight female the ovaries contain small follicles and the female fail to ovulate.  Some women suffer from a inflammatory disease called pelvic inflammatory disease and this blocks the oviducts.  Women also suffer endometriosis in which the presence of uterine tissue outside the uterus in the oviducts and the abdominal organs.  There is a backward flow of the menstrual flow allows living uterine cells to establish themselves in the abdominal cavity, where they go through the usual uterine cycle, causing pain and structural abnormalities that make it more difficult for a female to conceive.     There are alternatives that couples can consider in order to get pregnant.  One procedure is the in vitro fertilization.  This is when conception happens in a lab.  The immature egg is in a glass dish and is implanted with viable sperm.  After two to four days, the embryo is then transferred and implanted into the females uterus during the secretory phase of her uterine cycle.  If this goes well then the female should have a normal pregnancy.  Another form of infertility treatment is artificial insemination by donor.  This is when a male donates his sperm for woman who want to get pregnant.  The doctor administers the sperm into the female.  If possible the females partner  sperm is used.  Some people choose another route and that is a surrogate mother.  For some this is their only option because other treatments have failed.  The surrogate mother is when the male may donate his sperm and the female along with his sperm, can use her egg to be transferred into a "surrogate mother" (another person).  These surrogate mothers are paid to have babies.  This can be a dangerous alternative because sometimes the surrogate mother wants to keep the baby instead of giving it to the "infertile couple."

SEXUALLY TRANSMITTED DISEASES

Some sexually transmitted diseases can be fatal and are caused by viruses.  For instance AIDS (acquired immunodeficiency syndrome) or HIV (human immunodeficiency virus).  First people get the virus which can then turn into AIDS.  There is no cure for AIDS and many have died from this sexually transmitted disease.  Homosexual couples are the ones who are the most exposed.  The primary host for HIV is a helper T lymphocyte and these are the cells that stimulate am immune response.  The immune system of AIDS patients are extremely compromised.  There is a pneumonia called Karposi pneumonia that can kill the person who suffers from aids.  During the first stage of HIV infection there really isn't any symptoms.  People can go years without knowing that they have this virus unless they are tested.  They can infect other people because the virus is highly contagious.  After years with no symptoms, the  helper lymphocyte count falls and infection such as other STD's begin to appear.  In the last stage, called AIDS the helper T cells count falls way below normal leaving the person susceptible to more infections.   There is no cure, but most people living with this virus can seek treatment.  The treatment is called highly active antiretrovial therapy (HAART) and it usually is able to stop HIV reproduction to the extent that the virus becomes undetectable in the blood.  The medication has to be taken indefinitely because there is no cure and the virus could rebound.  Another STD is genital warts and this is also caused by a virus called the human papillomaviruses or HPV.   This virus can go undetected because the warts are sometimes flat and they occur on the penis of the male and around the vaginal opening in females.  This virus can be transmitted to others and the wart can recur.  There is a new treatment out for the genital warts and that is a vaccine.  They the development of this vaccine is extremely important in the prevention of cancer.  Genital warts have a link to cervical cancer and tumors of the vulva, vagina, anus and penis.  A similar STD closely related to genital warts is genital herpes.    They are caused by different viruses but they both produce warts or scabs around the genitalia.    Genital herpes is caused by the herpes simplex virus.  There is type I which causes cold sores and fever blisters and then there is type II that cause genital herpes.    Type II is more common in adults and some experience a tingling sensation before a blister appears on the genitals.  When the blisters rupture they leave a painful ulcer that may take as long as three weeks or as little as five days to heal.   After these do heal the virus is latent and blisters can recur.  This STD does not have a cure, but there are medications that can be taken to subdue outbreaks.   People need to be aware of STD and take precautions!

DEVELOPMENT WITH AGING

a.  fertilization

b.  pre-embryonic and embryonic development

c.  fetal development, fetal blood supply

d.  pregnancy and birth

e.  developmental after birth

www.bio.davidson.edu

 

This picture represents what happens when an egg and sperm come together and become a zygote.  This is called fertilization.   The little white box above shows just one sperm and what it consists of.  The tail is actually called flagellum and this helps the sperm swim towards the egg for fertilization.  Also, in the white box above you can see the middle portion which contain mitochondria which gives the sperm its energy.  The head of the sperm consists of a nucleus capped by a membrane bound acrosome.  The nucleus from the sperms head is what fuses with the egg nucleus.   The egg has a plasma membrane that is surrounded by a extracellular matrix called the zona pellucida and this is covered by layers of adhering follicular cells called corona radiata.  These cells nourish the egg when it is in a follicle of the ovary.   When fertilization takes place, several sperm try to penetrate the corona radiata and several try to penetrate zona pellucida but only one sperm enters the egg.  The acrosome has an acrosomal enzyme that eats through the jelly coat and then the head of the sperm adheres tightly to the zona pellucida and the acrosomal enzymes continue a pathway through the zona pellucida.  Then the sperm binds the egg connecting their plasma membranes.  The sperm enters the egg and then nucleus's fuses.  For the proper development to occur only one sperm should enter the egg.   When the sperm touches an egg the eggs plasma membrane depolarizes, making it so no other sperm  can penetrate it.   Also, vesicles called cortical granules release enzymes  that cause the zona pellucida to become an impermeable fertilization membrane and now sperm cannot bind to the zona pellucida either.   The pre-embryonic development has stages which I will explain each, but first here is a picture that gives the details of the processes that happen.

 www.mhhe.com

The first thing is the cleavage and the happens immediately after fertilization, the zygote begins divide so that there are first two then 4,8,16, and 32 cells and so on.  Increase in size does not accompany these divisions.  Cell division during cleavage is mitotic, and each cell receives a full complement of chromosomes and genes.  Next is growth, and with this during embryonic development, cell division is accompanied by an increase in size of the daughter cells.  Morphogensis refers to the shaping of the embryo and is first evident when certain cells are seen to move, migrate, in relation to other cells.  The embryo begins to assume various shapes. Differentiation is when cells take on a specific structure and function.  The first system to become visible differentiated is the nervous system.    As in the picture above you can see the morula which a compact ball of cells, and later becomes a blastocyst.  The many cells of the blastocyst arrange themselves so that there is an inner cell mass (also in pic) surrounded by an outer layer of cells.   The inner cell mass becomes the embryo and the layer of cells will become the chorion.

www.healthline.com

www.en.wikibooks.org

The pictures above represent the pre-embryonic development.  I love the second one because this picture is so life like.  The embryo also contains extraembryonic membranes that have specific functions.  The chorion develops into the fetal half of the placenta, the organ that nourishes the embryo/fetus and provides oxygen and takes away waste.  Blood vessels within the chorionic villi are continuous with the umbilical blood vessels.  The allantois, like the yolk sac, extends away from the embryo.  It accumulates the small amount of urine produced by the fetal kidneys and later gives rise to the urinary bladder.  The blood vessels become the umbilical blood vessels, which take blood to and from the fetus.  The umbilical arteries carry O2 poor blood to the placenta and the umbilical veins carry O2 rich blood from the placenta.   The yolk sac is the first embryonic membrane to appear.    This sac contains blood vessels and is the first site for blood formation.   Aminion enlarges as the embryo and then the fetus enlarges.  It contains fluid to cushion and protect the embryo.  Stages of development is from fertilization to birth.   I already went over the preembryoic development now we will go into the embryonic development.  It starts on the second week and last until the end of the second month of development. 

 

www.sciencehelpdesk.com

This picture shows the stages of embryonic development.  As it grows it get larger.  At the end of the first week the embryo starts to implant itself in the wall of the uterus.  When this is completed you are "clinically pregnant."  Sometimes the egg gets fertilized in the fallopian tube; this is called an ectopic pregnancy and it must be terminated because it can not grow in the fallopian tube.  During implantation, the chorion secretes enzymes to digest away some of the tissue and blood vessels of the endometrium of the uterus.  The chorion also start to secrete HCG (human chorionic gonadotropin) which is the hormone that is the basis of a pregnancy test.   This hormone also serves to maintain the corpus luteum past the time it normally would disintegrates.   Also, because the corpus luteum is being stimulated  it secretes progesterone so the endometrium is maintained and the expected menstruation doesn't occur.    The embryo is the size of a period, which you can see in the picture above.  As the embryo develops week after week the inner cell mass becomes the embryonic disk and two more extraembrynic membranes form.  The yolk sac is the first site of blood cell formation.  The amniotic cavity surrounds the embryo as it develops.   There is fluid in the amniotic cavity called amniotic fluid.  This fluid helps insulate and acts as a shock absorber.  The third week the nervous system is the first organ system to appear.   Also, development of the heart begins. In fifth week, the embryo starts to curve the head is large and you can see little stubs for limbs.  The sixth week the fingers and toes are present.  At two months, all organ systems are developed, bone is replacing cartilage and facial features are becoming clear.  Fetal development begins now.   In the third month you can tell what sex your baby will be.  The fourth month the hair starts to noticeable.  The fifth month the heartbeat can be heard.  Sixth month is when the skin is becoming wrinkled and reddish.  The seventh month, if a boy the testes descend into the scrotum, eyes are open, and they are getting longer.  The eighth month they are becoming fat.  Last but not least, the ninth month, the fetus is ready to be born and the mother is ready to give birth!!    Fetal blood supply is a very intricate thing. 

www.coolschool.ca

This picture shows how the fetus gets its blood supply.  As you can see in pink, that is the placenta that is formed by embryonic and uterine tissues.  the umbilical cord runs from the placenta to the fetus's what will soon be belly button.  The umbilical veins carry O2 rich blood and the arteries carry O2 poor blood.   Both the arteries and the veins are housed in the umbilical cord.    The umbilical vein enters the liver and then joins the venous duct which merges with the inferior vena cava; returns blood the heart.  The mixed blood enters the heart and is shunted to the left atrium through an oval opening.  An opening or hole between the right and left atria of the heart. This opening is covered with a flap that allows blood to move from the right atrium to the left atrium only. Movement of blood from the right atrium to the left side of the heart bypasses the lungs and allows the oxygenated blood from the placenta to be delivered to the body. Following birth and the cutting of the umbilical cord, blood begins to flow into and out of the lungs. Blood returning from the lungs to the left atrium closes the flap between the two atria.

PREGNANY TO BIRTH

When a women becomes pregnant she may experience morning sickness, fatigue, and loss of appetite.   Theses symptoms subside an new ones take their place.  Women get craving for certain foods or sometimes food they liked before becoming pregnant they don't like anymore.    Women gain weight, their breasts get bigger, and along with that comes back pain.  During birth the uterus contracts and this when a woman knows it is time for the baby to come out.  At first the contractions last 20 to 30 seconds and occurs every 15 to 20 minutes.  As the time decreases, the contractions come closer together.   Some woman have false-labor contractions and these are called braxton hicks contractions.  During the contractions that are close together, the cervical canal slowly disappears as the lower part of the uterus is pulled upward toward the baby's head.  The amniotic membrane ruptures and leak out of the vagina.  Then the cervix begins to dilate (becomes larger) to deliver the baby.  The contractions should be 1-2 minutes apart and last about a minute each.  These make the woman want to start pushing the baby out, but the cervix needs to be dilated at least 10 cm.   Some woman have to undergo a episiotomy, which is an incision that enlarges the opening, because they can't dilate.    the incision is sewn together after the baby is born.  The baby makes it way through the vagina and the umbilical cord is cut and clamped on the baby.  Then the woman has to deliver the placenta (afterbirth).   This usually takes a little while.  About 15 minutes after the birth of the baby the uterine muscular contraction shrink the uterus and dislodges the placenta.   After the birth of the baby development does not stop.  The baby will continue to develop and go through stages like infancy, childhood, adolescence, and adulthood.  All of these stages have different effects on the body. 

www.swimwithbaby.com

Here is a picture of the tiny baby's hand holding a mothers hand.  See we never stop developing!   Physical changes can be seen,  but there are a lot of changes happening inside our bodies too!