Ethical Essay Unit Iv

I feel that the people who should reproduce are those who can care for their children and be able to support them without having the help of everyone in the community. We see so many more high school girls having babies with guys who they meet one time. It's getting ridiculous. There are so many people who live off of well fare and dont feel that they need to go out and look for a job to support thier kids. Women sit at home and collect child support, and do nothing, its getting ridiculous. It used to be that having a child was a special time and any more it seems like its an easy way for money. I think that if you are going to have a child you need to make sure that you can support him/her financially on your own, without depending on the county food stamps or W.I.C. I would not neccesarly put an age limit on the time to have achild i would say that you should be at least 20 just because 16,17,18 your still a child you self.

Review Unit IV 22,23,24

Chapter 22 Review

Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a progression that includes the most advanced animals and plants. Exactly how evolution occurs is still a matter of debate, but that it occurs is a scientific fact. Biologists agree that all living things arose through a long history of changes shaped by physical and chemical processes that are still taking place. It is plausible that all organisms can be traced back to the origin of LIFE from inanimate matter.
The most direct proof of evolution is furnished by the science of PALEONTOLOGY, or the study of life in the past through fossil remains or impressions, usually in rock. Additional evidence comes from comparative studies of living animals and plants, including their structure (COMPARATIVE ANATOMY), BIOCHEMISTRY, EMBRYOLOGY, and geographical distribution. Approximately 2 million different species of organisms are now living, but it is estimated that at least 99.9 percent of the species that have ever lived are now extinct and that some 2 billion species have evolved during the past 600 million years.
Changes occur in living organisms that serve to increase their adaptability, or potential for survival and reproduction, in the face of changing environments. Evolution apparently has no built-in direction or foreordained purpose. A given kind of organism may evolve only when it occurs in a variety of forms differing in hereditary characteristics, or traits, that are passed from parent to offspring. Purely by chance, some varieties prove to be ill adapted to their current environment and thus disappear, whereas others prove to be adaptive, and their numbers increase. The elimination of the unfit, or the "survival of the fittest," is known as NATURAL SELECTION because it is nature that discards or favors a particular variant. Basically, evolution takes place only when natural selection operates on a population of organisms containing diverse inheritable forms. Recently, natural selection was demonstrated for the first time outside of the laboratory when scientists observed guppies change their reproductive behavior over an 11-year period in direct response to being transferred to a new environment that had different predators.

Chapter 23 Review

Ecology is the scientific study of the relationship between plants and animals and their environment. Ecologists study and analyze the complex interactions between organisms and the world around them in populations, communities and ecosystems. By studying the inter-relationships between living and non-living things, ecologists gain valuable information that can be used to help protect and preserve the environment for future generations. Before we discuss ecology on a global scale, we must first define some of the common terms used in ecology.
A habitat is an organism’s environment. Related to the habitat is the niche of an organism, which is the function of that organism within a habitat. In other words, the habitat describes where a living thing dwells, while the niche tells what it does.
The word ‘population’ is used in ecology to describe a single species population. A group of individuals belonging to one species (of bacteria, fungi, plant, or animal) living in an area is a population. The subfield of ecology that deals with populations focuses on the number of organisms that live in a particular area and the biological and physical factors that sustain them.
A community is a group of populations of different organisms that interact with one another in a given habitat or area. Within a community, all the organisms are interdependent (that is, they depend on each other for survival).
An ecosystem is a large area where materials are exchanged between living communities and nonliving things. This exchange of materials depends on the decomposition of living organisms and the intake of inorganic materials into living organisms (to put it simply, this means eating). Balance is extremely important in an ecosystem, where disturbances and slight fluctuations in stability can threaten the lives of the organisms within the system. Ecosystems are basically self-contained energy and nutrient cycles. Soil, air, water, sunlight, minerals, and nutrients are all important components of a healthy ecosystem.
Finally, a biome is the largest ecological unit. It consists of many ecosystems which interact with each other in complex ways. Different biomes are distinguised from each other by variations in climate, rainfall, soil type, food sources, plants and animals. There are nine major terrestrial biomes: coniferous forest, desert, grassland, mediterranean, mountain, rainforest, savanna, temperate forest, and tundra. There are also aquatic biomes: coastal waters, coral reef, freshwater, and open ocean, to name only a few.
Unfortunately, human activity has caused significant damage to ecosystems and biomes worldwide. Pollution has destroyed many ecological habitats throughout the world beyond hope of repair. Myriad species of organisms have become extinct without ever being discovered and potential forms of medicine have died with them. The devastation that the human species has caused through the exploitation of natural resources and the sake of making money is sickening. Disturbing the global ecology of our planet will have serious repercussions in the future. For this reason, ecology is an important field of study. By studying the relationships between biotic and abiotic things, we will gain an understanding of and an appreciation for the incredibly complex world we live in. This understanding will help us improve the environment, manage natural resources and ultimately protect the health of the planet Earth.(http://library.thinkquest.org/C003763/index.php?page=planet04)

Chapter 24:

Birth rate (b) − death rate (d) = rate of natural increase (r).
birth rate expressed as number of births per 1000 per year (currently 14 in the U.S.);
death rate expressed as the number of deaths per 1000 per year (currently 8 in the U.S.);
So the rate of natural increase is 6 per thousand (0.006 or 0.6%).
Although the value of r is affected by both birth rate and death rate, the recent history of the human population has been affected more by declines in death rates than by increases in birth rates.
The graph shows birth and death rates in Mexico since 1930. The introduction of public health measures, such as
better nutrition
greater access to medical care
improved sanitation
more widespread immunization has produced a rapid decline in death rates, but until recently there was no corresponding decline in birth rates. In 2007, r is 1.7%. (Data from the Population Reference Bureau.)
Although death rates declined in all age groups, the reduction among infants and children had — and will continue to have — the greatest impact on population growth. This is because they will soon be having children of their own.
This situation, resulting in a rapid rate of population growth, is characteristic of many of the poorer regions of the world.
The Demographic Transition
Slowly declining birth rates following an earlier sharp decline in death rates are today characteristic of most of the less-developed regions of the world.
The shift from high birth and death rates to low birth as well as death rates is called the demographic transition.
This graph (based on data from the Population Reference Bureau) shows that the demographic transition began much earlier in Sweden than in Mexico and was, in fact, completed by the end of the nineteenth century. The spike in deaths in the interval between 1901 and 1926 was caused by the worldwide influenza pandemic of 1918–1919.
The birth rate in Sweden is now (2007) 12/1000; the death rate 10/1000, giving a rate of natural increase (r) of 0.2

Unit IV Online-Lab

*** I'm Sorry but the pictures were not wanting to save and upload for this lab idk why. I could only get 1 to save. **

1. What was your high fertility rate country and what was its fertility rate?The United States. The fertility rate set at 10.2. What was your low fertility rate country and what was its fertility rate?China. The fertility rate set at 2.3. 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?When the fertility rate was increased, then the fertility rate results in a high percentage of young people in the population. This would affect future population growth because there would be more young people having children, and therefore the percentage of young people would continue to rise.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.The set fertility rate was set at two, which can result in a high population in middle age groups. This would affect future population growth because there would be more adults, and therefore the percentage of children would decrease.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 (phoenix, Arizona?). Then do the same for a situation with lots of children in the population.Younger population: Chaotic, crazy, immature, weird, riot, loud, noisy, disorganized, incompetent, confused, unorganized and low income, more welfare.

Unit IV Overview

REGARDING YOUR OWN PERFORMANCE
1. What were the three aspects of the assignments I've submitted that I am most proud of? My Species Lab, my photos, and my ch. 16 review
2. What two aspects of my submitted assignments do I believe could have used some improvement? Possibly both of my quizzes
3. What do I believe my overall grade should be for this unit? I believe an A. I worked hard and took several hours reserching for the lab and doing photos.
4. How could I perform better in the next unit?
Well every unit i learned from and felt like overall i kept getting better over the semester and really enjoyed this class.

REGARDING THE UNIT (adapted from Stephen Brookfield, University of St. Thomas "Critical Incident Questionnaire")
At what moment during this unit did you feel most engaged with the course? During the lab while taking the photos.

At what moment unit did you feel most distanced from the course? During the online lab with pregnancy

What action that anyone (teacher or student) took during this unit that find most affirming and helpful? The teacher by doing the online verbal sessions.

What action that anyone (teacher or student) took during this unit did you find most puzzling or confusing? There was none at all.

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 to you.) At first i did not feel that i was going to like this unit at all and i suprisingly did.

Online Lab Unit IV

The Photos above all show the different stages of development during the weeks of pregnacy.

About 1 month before conception: Almost all adult males produce thousands of spermatozoa (male germ cells) each second. It would take about 500 of them lined up in a row to total 1 inch in length. They take a month or so to travel from a testicle, through a long tube called the "vas deferens," to reach a small reservoir inside the man's prostate gland. Here, semen (a mixture of spermatozoa and various fluids) is formed. Each spermatozoon contains human DNA. They certainly appear to be living organisms. As seen in a microscope, they seem to be moving energetically with the sole motivation of fusing with an ovum. Most people consider them to be a form of human life, because they appear alive and contain human DNA. Some scientists define "life" so strictly that spermatozoon are not considered alive. Its movements are due to chemical reactions.
Perhaps one day before conception: The woman ovulates and produces one mature ovum (egg cell). It travels down one of her fallopian tubes towards her uterus. It is about 1/100" in diameter, and is barely visible to the naked eye. It also considered by most of the public to be a form of human life, for the above reasons. But it does not meet some scientists' strict definition of a living organism, because it lacks one factor: the ability by itself to reproduce. It can only reproduce with the assistance of a spermatozoon. Some of these scientists have described an ovum as an "inert globule of organic matter." It does carry a cargo of human DNA.
At conception: One very lucky spermatozoon out of hundreds of millions ejaculated by the man will penetrate the outside layer of the ovum and fertilize it. This happens typically in the outer third of one of the woman's Fallopian tubes. The surface of the ovum changes its electrical characteristics and normally prevents additional sperm from entering. A genetically unique entity is formed shortly thereafter, called a zygote. This is commonly referred to as a "fertilized ovum." However that term is not really valid because the ovum ceases to exist after conception. Half of the zygote's 46 chromosomes come from the egg's 23 chromosomes and the other half from the spermatozoon's 23. It has a unique DNA structure, different from that of the ovum and the spermatozoon. The zygote "...is biologically alive. It fulfills the four criteria needed to establish biological life:
metabolism,
growth,
reaction to stimuli, and
reproduction." 1
It can reproduce itself through twinning at any time up to about 14 days after conception; this is how identical twins are caused.Conception is the point that most, or all, pro-life groups and conservative Christians define as the beginning of pregnancy. 8 Most of these groups define the start of a human person as occurring at conception. The medical definition of the start of pregnancy is about 10 days later, at implantation. The zygote divides into two cells, called blastomeres. They subdivide once every 12 to 20 hours as the zygote slowly passes down the fallopian tubes.
About 3 days after conception: The zygote now consists of 16 cells and is called a 16 cell morula (a.k.a. pre-embryo). It has normally reached the junction of the fallopian tube and the uterus.
5 days or so after conception: A cavity appears in the center of the morula. The grouping of cells are now called a blastocyst. It has an inner group of cells which will become the fetus and later the newborn; it has an outer shell of cells which will "become the membranes that nourish and protect the inner group of cells." 3 It has traveled down the fallopian tubes and has started to attach itself to the endometrium, the inside wall of the uterus (a.k.a. womb). The cells in the inside of the blastocyst, called the embryoblast, start forming the embryo. The outer cells, called the trophoblast, start to form the placenta. It continues to be referred to as a pre-embryo. 2
9 or 10 days after conception: The blastocyst has fully attached itself to endometrium. Primitive placental blood circulation has begun. This blastocyst has become one of the lucky ones. Most never make it this far in the process.
12 days or so after conception: The blastocyst has started to produce hormones which can be detected in the woman's urine. This is is the event that all (or almost) all pro-choice groups and almost all physicians (who are not conservative Christians) define to be the start of pregnancy. If instructions are followed exactly, a home-pregnancy test may reliably detect pregnancy at this point, or shortly thereafter.
13 or 14 days after conception: A "primitive streak" appears. It will later develop into the fetus' central nervous system. This is the point at which spontaneous division of the blastocyst -- an event that sometimes generates identical twins -- is not longer possible. The pre-embryo is now referred to as an embryo. It is a very small blob of undifferentiated tissue at this stage of development.
3 weeks: The embryo is now about 1/12" long, the size of a pencil point. It most closely resembles a worm - long and thin and with a segmented end. Its heart begins to beat about 18 to 21 days after conception. Before this time, the woman might have noticed that her menstrual period is late; she might suspect that she is pregnant and conduct a pregnancy test. If it is an unwanted pregnancy, she might have already arranged and carried through with an abortion.
4 weeks: The embryo is now about 1/5" long. It looks something like a tadpole. The structure that will develop into a head is visible, as is a noticeable tail. The embryo has structures like the gills of a fish in the area that will later develop into a throat.
5 weeks: Tiny arm and leg buds have formed. Hands with webs between the fingers have formed at the end of the arm buds. Fingerprints are detectable. The face "has a distinctly reptilian aspect." 1 "...the embryo still has a tail and cannot be distinguished from pig, rabbit, elephant, or chick embryo." 3
6 weeks: The embryo is about 1/2" long. The face has two eyes on each side of its head; the front of the face has "connected slits where the mouth and nose eventually will be." 1
7 weeks: The embryo has almost lost its tail. "The face is mammalian but somewhat pig-like." 1 Pain sensors appear. Many conservative Christians believe that the embryo can feel pain. However, the higher functions of the brain have yet to develop, and the pathways to transfer pain signals from the pain sensors to the brain have not developed at this time.
2 months: The embryo's face resembles that of a primate but is not fully human in appearance. Some of the brain begins to form; this is the primitive "reptilian brain" that will function throughout life. The embryo will respond to prodding, although it has no consciousness at this stage of development. The brain's higher functions do not develop until much later in pregnancy.
10 weeks: The embryo is now called a fetus. Its face looks human; its gender may be detectable via ultrasound.
13 weeks or 3 months: The fetus is about 3 inches long and weighs about an ounce. Fingernails and bones can be seen. Over 90% of all abortions are performed before this stage. 9
17 weeks or 3.9 months: It is 8" long and weighs about a half pound. The fetus' movements may begin to be felt. Its heartbeat can usually be detected.
22 weeks or 5 months: 12" long and weighing about a pound, the fetus has hair on its head. Its movements can be felt. An abortion is usually unavailable at this gestational age because of state and province medical society regulations, except under very unusual circumstances. Half-way through the 22nd week, the fetus' lungs may be developed to the point where it would have a miniscule chance to live on its own. State laws and medical association regulations generally outlaw almost all abortions beyond 20 or 21 weeks gestation. "A baby born during the 22nd week has a 14.8 percent chance of survival. And about half of these survivors are brain-damaged, either by lack of oxygen (from poor initial respiration) or too much oxygen (from the ventilator). Neonatologists predict that no baby will ever be viable before the 22nd week, because before then the lungs are not fully formed." 4 Of course, if someone develops an artificial womb, then this limit could change suddenly.Fetal survival rate: "Most babies at 22 weeks are not resuscitated because survival without major disability is so rare. A baby's chances for survival increases 3-4% per day between 23 and 24 weeks of gestation and about 2-3% per day between 24 and 26 weeks of gestation. After 26 weeks the rate of survival increases at a much slower rate because survival is high already." 5
26 weeks or 6 months: The fetus 14" long and almost two pounds. The lungs' bronchioles develop. Interlinking of the brain's neurons begins. The higher functions of the fetal brain turn on for the first time. Some rudimentary brain waves can be detected. The fetus will be able to feel pain for the first time. It has become conscious of its surroundings. The fetus has become a sentient human life for the first time.
7 months: 16" long and weighing about three pounds. Regular brain waves are detectable which are similar to those in adults.
8 months: 18" long and weighing about 5 pounds.
9 months: 20" long and with an average weight of 7 pounds, a full-term fetus' is typically born about this time.

References that were used:
Carl Sagan, "Billions and Billions", Random House, New York NY (1997), Pages 163-179.
This ultrasound picture of a fetus at 2.8 month/12 week gestation was donated by a visitor to this web site.
C. George Boeree, "General Psychology: Prenatal development," at: http://www.ship.edu/~cgboeree/genpsyfetaldev.html
Franklin Foer, "Fetal Viability," The Gist, 1997-MAY-25, at: http://www.slate.com/id/1060/
"Chances for Survival," University of Wisconsin Medical School, 2004-APR-22, at: http://www.pediatrics.wisc.edu/patientcare/preemies/anticipating.html#survival

Unit IV Lab

YUCCA

SCIENTIFIC NAME: YUCCA SCHDIGERA

ECOLOGICAL Principle: Commensal

Common Name: Yucca

This is a domesticated plant species & is used very often

Pine tree:

Scientific name: pinus monticola

Common name :Pine tree

Ecological principle :mutualism

This is considered a domesticated species because we are able to have them in our yards.

Quail:

Scientific name -Colinus virginianus

Common name -Quail

Ecological principle -Commensal

A non-domesticated species of bird, and people don’tCommonly own these.

Rose:

Scientific Name:

Common Name: Rose

Ecological Principle: Mutualism

A domesticated plant species, people do own these

Spruce:

Scientific name -Picea

Common name -Spruce

Ecological principle - Commensal

A domesticated plant species, but is free also

Weeping Willow

Common Name: Weeping Willow

Ecological Principle: Commensal

A domesticated plant species, as well as free.

Butterfly

Common Name: Butterfly

Ecological Name: Commensal

A non-domesticated species of ansects cause they are not usually owned as pets.

Cheese:

Scientific name: Caseus

Common name :Cheese

Ecological principle: Commensal

A domesticated species because it is in our food

Coyote:

Scientific name :Canis latrans Say

Common name : Coyote

Ecological principle: Commensal

A non-domesticated version of a dog, which people don’t usually own.

Juniper:

Scientific name :Juniperus

Common name :Juniper

Ecological principle :Commensal

A domesticated plant species, people can have these

Mango:

Common Name: Mango

Ecological Principle: Commensal

Domesticated species because it is in our food.

Mesquite:

Scientific name: Prosopis

Common name:Mesquite

Ecological principle:Commensal

A domesticated plant species, but is free also

Lizard:

Scientific Name:Cope

Common Name: Lizard

Ecological Name: Commensal

A non-domesticated species of reptile, people can own them but do not usually.

Banana:

Scientific name:Musa acuminata Colla

Common name:Banana

Ecological principle:Commensal

A domesticated species because it is in our food Sagebrush:

Scientific name:Artemisia

Common name:Sagebrush

Ecological principle:Commensal

A domesticated plant species

Cricket:

Scientific name:Anabrus simplex

Common name:Cricket

Ecological principle:Commensal

A non-domesticated species of insect because people don’t usually own as pets

Cactus:

Scientific name:Peromyscus eremicus

Common name:Cactus

Ecological principle:mutualism

A domesticated species because it is a plant that people can have, but usually grows outdoors

MILK:

Scientific Name: Silybum, Common Name: Mmilk, Ecological Principle- Commensal, domesticated species because its in our food.

Squirrels:

Scientific name:Sciurus aberti Common name:Squirrel Ecological principle:Commensal, a non-domesticated species, because people don’tUsually own squirrels as pets

Yogrut :

Scientific name :Lactobacillus bulgaricus Common name:Bacteria in yogurt Ecological principle: Commensal, A domesticated species because it is in our food

Skunk:

Scientific name:Conepatus mesoleucus Common name:Skunk Ecological principle:Parasitic, A non-domesticated species because people don’tUsually own these as pets, and avoid contact with them

CROW:

Scientific name:Geococcyx californianus Common name: CROW Ecological principle: Commensal. A non-domesticated species of bird, which people don’t usually own.

Pigeons:

Scientific name ~ Columba fasciata Common name~ Pigeon Ecological principle ~ Commensal. A non-domesticated species of bird, which peopleDon’t usually own

Green algae:

Scientific name: Halimeda cuneata Common name:Green algae Ecological principle: Commensal. A non-domesticated species because it grows freely outdoors

PUGS:

Scientific name: Canis familiaris Common name: PUG Ecological principle:Symbiotic

A domesticated species because of evolution.

BOSTON TERRIER:

Scientific name: Canis familiaris Common name: Boston Terrier Ecological principle: Symbiotic. A domesticated species because of evolution.

BigHorn Sheep:

Common Name: Big horn, Ecological Priniciple: Commensal. A non-dometicated species, people do not normally own them.

Buffalo:

Common Name. Buffalo, Ecologoical Name: Commensal, A non-domesticated animal they normally live on thier own.

CHIMPUNK:

Scientific Name: Eutamias, Common Name: Chipmunk, Ecological Principle: Commensal, non-domesticated because people usually do not own them as pets.


Coffee:

Scientific name:Gymnocladus dioicus Common name: Coffee Ecological principle: Commensal This is considered a domesticated species because it is in our food

Unit IV Write-Up Sec. 1

16 & 17 Reproducative System

16.1 Human Life Cycle

There are about four stages to the human life cycle (depending on how you look at it). They are Infancy, Childhood, Adolescence and Adulthood. Most likely if you are in Jr. High School or High School, you are in the adolescence stage.
The four stages will be described below briefly to help you understand what the basic of the human life cycle are.
Infancy- From the age of being a newborn to the age of two years, you were an infant. Changes you may have experienced were more coordination and teeth growing rapidly. The body was also quite out of proportion . These were all part of the infancy stage.
Childhood- Childhood lasts from the age of two years to adolescence. Your bones and teeth were growing rapidly and soon changes such as teeth being replaced with permanents happen. You also develop your intellectual skills (ABC's, reading/writing) and pretty much you have quite changed from being an infant.
Adolescence- Adolescence is the age where the body becomes sexually mature. Changes you may be going through are acne, increased growth and deeper voice. Girls also gain extra weight during this time. It is sometimes a emotionally distressing time for teenagers.
Adulthood- Adulthood is the age where the body slowly slows down. Certain changes such as hair falling out and physical activity decreasing are normal as you age . If you are over forty, you are considered a older adult. This however doesn't stop someone from doing the things they enjoy.

16.2 Male Reproductive System

The purpose of the organs of the male reproductive system is to perform the following functions: To produce, maintain and transport sperm (the male reproductive cells) and protective fluid (semen), To discharge sperm within the female reproductive tract during sex, To produce and secrete male sex hormones responsible for maintaining the male reproductive system. Penis: This is the male organ used in sexual intercourse. It has 3 parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped part at the end of the penis. Scrotum: This is the loose pouch-like sac of skin that hangs behind the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. Testicles (testes):

These are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes.

16.3 Female Reproductive System

The female reproductive system contains two main parts: the vagina and uterus, which act as the receptacle for the man's sperm, and the ovaries, which produce the female's ova. All of these parts are always internal; the vagina meets the outside at the vulva, which also includes the labia, clitoris and urethra. The vagina is attached to the uterus through the cervix, while the uterus is attached to the ovaries via the Fallopian tubes. At certain intervals, the ovaries release an ovum, which passes through the fallopian tube into the uterus.If, in this transit, it meets with sperm, the sperm penetrate and merge with the egg, fertilizing it. (Wikipedia)

16.4 Femal Hormone Level

Although we tend to think of hormones kicking in at puberty, they affect our bodies even during early childhood. At puberty, hormones will begin to make major, lasting changes to a girl's body. Her breasts will get bigger and take on the shape of an adult woman's breasts. She will develop underarm and pubic hair and will get noticeably taller as a significant growth spurt occurs. Eventually her periods will start, usually as the growth spurt is beginning to slow down. Female sex hormonesThe most important hormones made by the ovaries are known as female sex hormones (sex steroids) and the two main ones are oestrogen and progesterone. If the egg released from the ovary is fertilised and a pregnancy results, a woman's hormones change dramatically. The usual fall in oestrogen and progesterone at the end of the menstrual cycle doesn't occur, so no period is seen. After childbirth, what then? Levels of oestrogen, progesterone and other hormones fall sharply, causing a number of physical changes. The womb shrinks back to its non-pregnant size, pelvic floor muscle tone improves and the volume of blood circulating round the body returns to normal. The next significant hormonal change for most women occurs around the time of the last period - the menopause. Over three to five years leading up to a woman's last period, the normal functioning of her ovaries begins to deteriorate. This can cause her menstrual cycle to become shorter or longer, and sometimes it becomes quite erratic. Periods may become heavier or lighter. Eventually, the ovaries produce so little oestrogen that the lining of the womb fails to thicken up and so periods stop altogether.

16.5 Control Of Reproduction

There are several types of control now such as birth control pill, diaphragm, and condom. Also assistantce in trying to have a baby, invitro fertilization, and GIFT.

16.6 Sexualy Transmitted Diseases

A sexually transmitted disease (STD) or venereal disease (VD), is an illness that has a significant probability of transmission between humans or animals by means of sexual contact, including vaginal intercourse, oral sex, and anal sex. Increasingly, the term sexually transmitted infection (STI) is used, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without showing signs of disease. Some STIs can also be transmitted via kissing, use of an IV drug needle after its use by an infected person, as well as through childbirth or breastfeeding. Sexually transmitted infections have been well known for hundreds of years.

CHAPTER 17

17.1 Fertilization

Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. It is also the initiation of prenatal development.
Fertilization constitutes the penetration of the oocyte which the sperm performs, fusion of the sperm and oocyte, succeeded by fusion of their genetic material.

17.2 Pre-Embryonic an Embryonic Development

Fertilization occurs about 24 hours before the egg is laid. A sperm cell, actually a number of sperm cells, penetrates the blastodisc on the yolk, and a new life begins. When the egg is laid, the blastoderm contains several hundred cells. When the egg cools, embryonic development stops. Embryonic development starts again when the temperature is increased. If the temperature is then decreased to room temperature a second time, the embryo will die.
Prior to incubation, all cells in the embryo look the same and have the same function. That changes, however, during the first 4 days of incubation. As cell division continues, the cells receive messages that cause them to become different types of tissues and organs. Some cells will develop into the circulatory system, others into the brain, and still others into muscles. The process in which similar cells are instructed to take on different functions is called differentiation. The first 4 days are a time of dramatic change. Mistakes sometimes occur in this process. If it is a serious mistake, the defect is lethal and the embryo dies. In the incubation process, these mistakes cause "early deads." If the biological mistake is not as serious, the embryo may develop longer before dying, or it may survive with a congenital defect.
While the embryo is developing, temporary structures are formed to support life. They are called extra-embryonic, because they do not become a part of the embryo. The one that is visible at the earliest stage of development is the amnion. It looks like a small pool in which the embryo is floating. Its purpose is to protect the embryo. The allantois is a structure that collects the waste that the embryo produces before it hatches. Many of the nutrients that the embryo needs are removed from the yolk by the yolk sac. Its blood vessels can carry nutrients from the yolk to the embryo. The last structure is the chorion, which lies between the embryo and the shell. An important function is for it to exchange the carbon dioxide produced by the embryo and bring oxygen to the embryo. The chorion also is important for dissolving mineral from the shell and making it available to the chick for forming bones.

17.3 Fetal Development

Day 1 - conception takes place.
7 days - tiny human implants in mother’s uterus.
10 days - mother’s menses stop.
18 days - heart begins to beat.
21 days - pumps own blood through separate closed circulatory system with own blood type.
28 days - eye, ear and respiratory system begin to form.
42 days - brain waves recorded, skeleton complete, reflexes present.
7 weeks - photo of thumbsucking.
8 weeks - all body systems present.
9 weeks - squints, swallows, moves tongue, makes fist.
11 weeks - spontaneous breathing movements, has fingernails, all body systems working.
12 weeks - weighs one ounce.
16 weeks - genital organs clearly differentiated, grasps with hands, swims, kicks, turns, somersaults, (still not felt by the mother.)
18 weeks - vocal cords work – can cry.
20 weeks - has hair on head, weighs one pound, 12 inches long.
23 weeks - 15% chance of viability outside of womb if birth premature.*
24 weeks - 56% of babies survive premature birth.*
25 weeks - 79% of babies survive premature birth.*

17.4 Pregancy at Birth

is the culmination of a human pregnancy or gestation period with the delivery of one or more newborn infants from a woman's uterus. The process of human childbirth is categorized in 3 stages of labour. The first stage accomplishes the shortening and then the dilation of the cervix. It is deemed to have started when the cervix is 3 cm dilated, and ends with full dilation. Contractions begin in the first stage of labour although they may be irregular and sporadic at first. The second stage, often called the pushing stage, starts when the cervix is fully dilated and ends with the expulsion of the fetus. In the third stage, the placenta detaches from the uterine wall and is expelled through the birth canal.Preceding the onset of labour is a period called the latent phase. This phase may last many days, and the contractions are an intensification of the Braxton Hicks contractions that start around 26 weeks gestation. Latent phase ends with the onset of active first stage labour.

17.5 Development after Birth
For nine months the placenta feeds and nourishes the foetus while also disposing of toxic waste. Without it the foetus would not survive. After the baby is born, the placenta, while thought by most to no longer serve a function, actually has two. If not severed, it supplies the symbiote foetus with oxygenated blood cells as it makes the transition to become an air-breathing infant and it contains all the nutrients and ingredients needed by the mother to replenish those excreted during the birth process and thus help her body recover.