Compendium Review: Unit 4: Chapters 16 & 17

Compendium Review: Unit 4: Chapters 16 & 17

Reproduction
Table of Contents:
I. Introduction
II. Human Life Cycle
A. Events of Human Life Cycle
III. Meiosis: Eggs and Sperm
A. Male Reproductive Organs
1. structure and function
2. process of meiosis
3. vasectomy
B. Female Reproductive Organs
1. structure and function
2. process of meiosis
3. menstrual cycle
C. Birth Control Options
D. Sexually Transmitted Diseases
1. types of STDs
2. Hepatitis
3. other common infections
4. prevention of STDs
IV. Fetal Development and Birth
A. Fertilization and Implantation
B. Early Embryonic Development
1. early weeks
2. from fetus to adult
C. Fetal Development
D. Pregnancy
1. change in female anatomy
E. Birth
1. stages
2. birthing, cultures, children
V. Conclusion

I was shocked when I first realized that I was going to become a parent. Originally, I had not planned to start a family in the fall of 2005, but instead I was going to school full-time and enjoying my early twenties. But, when I look upon the past today, I am so blessed that the choices I had made has given me such a beautiful and amazing spirit. She has shown a new world to me through different eyes, giving the purpose and drive for my life. And, my daughter has made me into such an empowered individual. In accordance with Human Biology, the different processes of reproduction are very important to the continuation of life, not only on a spiritual level but on a biological level as well. There are three major parts of life that contribute to reproduction, which are: the human life cycle, meiosis (eggs and sperm), and fetal development and birth.

In the human life cycle, there are several events that take place. They are: meiosis, fertilization, fetal development, birth, childhood/adolescence, adulthood (meiosis), aging, and death. The process of meiosis is a reduction division of cells, because “…meiosis involves two divisions… (with)…four daughter cells. Each daughter cell has one of each kind of chromosome and, therefore, has as many chromosomes in the parent” (Mader 385). Meiosis allows for the process of fertilization to take place, because it combines the DNA of the male sperm and the female egg that creates a new individual with a complete set of inherited chromosomes. The process of fertilization leads to the growth of a new individual from fetal development. In fetal development, the new life matures within the uterus of the female parent for a time period of nine months until the baby is brought into the world by the occurrence of birth. Birth allows for the uterus to contract and eases the baby into the external environment via the birth canal. Then, the baby grows into childhood/adolescence and adulthood, where development of the brain and other bodily systems continues. Also, in adulthood, the process of meiosis begins to occur in order for the process of reproduction to occur over and over again. As the individual proceeds to mature, the slow process of aging occurs. This causes the changes in the human body that contributes to increase risk of illness, disease, and eventually the occurrence of death. One of the major events of the human life cycle, meiosis, occurs in particular regions within the human body.

The event of meiosis in the human life cycle occurs within the reproductive organs in males and females. The male reproductive system consists of several structures and functions. Some of the reproductive organs of males are: the testes, the epididymides, the vas deferens, the seminal vesicles, the prostate gland, the urethra, and the penis. The testes are the primary sex organs, or male gonads, which are perched in pairs inside sacs. This is where the sperm and sex hormones are mainly produced. The epididymides is a, “…tightly coiled duct lying just outside each testis” (Mader 321) and is where the maturation of sperm occurs. After the sperm is fully matured, they leave the epididymides and travel through the vas deferens. The vas deferens is a small tube that passes up into the area of the abdominals and around the bladder. This organ allows for the sperm to be stored for a certain period of time. The vas deferens also empties into an ejaculatory duct that leads to the urethra, which is located at the base of the penis. The urethra is a tubular structure that manages sperm and also permits the passage of urines from the bladder. After the incidence of ejaculation, where the sperm is expelled out of the penis in fluid called semen, the seminal vesicles and prostate gland add particular secretions to the semen fluid. The seminal vesicles are located at the base of the bladder in pairs, that each lead to ducts of the vas deferens. And, the prostate gland, which is donut-like in appearance, is located just below the bladder and surrounds an upper portion of the vas deferens. Lastly, the penis is the, “…male organ of sexual intercourse” (Mader 322) that is shaped as a long shaft with an inflated tip. The semen is ejaculated from the penis from intensity of sexual stimulation. The process of meiosis happens within particular parts of these reproductive organs.
Figure 1: The male reproductive system: testes, epididymides, vas deferens, seminal vesicles, prostate gland, urethra, & penis.

Inside the organ of the testes, there are small compartments that contain tightly curved seminiforous tubules. Inside the walls of the seminiforous tubules, the process of spermatogenesis, which is meiosis in males, takes place. The sperm cells begin with a single producer that divides into the primary spermatocytes that constantly undergo the process of meiosis. After the stage of meiosis is complete, the spermatocytes finally change into sperm. Then, the sperm are collected in the epididymides, where it follows the functions of the different reproductive organs and is eventually ejaculated. But, sperm that is not ejaculated is taken back into the tissue of the testes. The male reproductive organs can also be altered by scientific methods.
A particular process, called vasectomy, allows for the occurrence of sterility of an individual. The method of a vasectomy consists of cutting the vas deferens, so the sperm cannot be combined with the semen that is ejaculated by the penis. The sperm still follow the same process though, but are reabsorbed into the tissue of the testes due to the unnecessary use of them. Along with the male reproductive system, the event of meiosis also occurs in the reproductive system of females.
The female reproductive system consists of several structures and functions. Some of the reproductive organs of females are: the ovaries, the oviducts, the uterus, the cervix, and the vagina. The ovaries are the primary sex organs, or female gonads, that lie in depressions of the upper pelvic cavity in pairs. This is where the eggs and female sex hormones are produced. The oviducts extend from the uterus and lead to the ovaries and are, “…finger-like projections called fimbriae that sweep over the ovaries” (Mader 324). This is where the eggs are controlled after it bursts out of the ovary. And, once the egg is within the oviduct, it is slowly moved towards the uterus by ciliary actions and muscle contraction. The uterus is as muscular organ that is surrounded by a thick wall of muscle. It lies above the urinary bladder and at the top portion, is joined by the oviducts, and at the bottom portion, is joined by the cervix. It is within the uterus that the developing fetus is housed, if an egg is fertilized. And, the cervix, which is located at the end of the uterus and enters into the vagina, is the opening to the uterus. Lastly, the vagina is muscular tube that consists of folds that allows for the facilitation of sexual intercourse, the birth of babies, and the exit of menstrual flow. The vagina also contains external structures that make up the genitals. It consists of the clitoris and the labia majorium. The clitoris is the organ of sexual arousal that extends from the pubic bone and is alike in structure to the penis, which contains a shaft of erectile tissue. And, the labia majorium is a fatty prominence that lies underneath the pubic hair that surrounds the clitoris, urethra, and vaginal opening. The process of meiosis happens within particular parts of these reproductive organs.
Figure 2: The female reproductive system: ovaries, oviducts, uterus, cervix, & vagina.

Inside the organ of the ovaries, there are several follicles that contain oocytes, which are immature of eggs. During the ovarian cycle, a follicle will mature and will allow for the process of oogenesis, which is the process of meiosis in females. A mature follicle will undergo the reduction of cells that result in the haploid daughter cells that contain half their chromosomal number. But, the second phase of meiosis, which creates four daughter cells, can only occur if an egg becomes fertilized by a sperm. The oocyte will not complete the second stage of meiosis if left unfertilized and will die shortly after the follicle bursts and releases it from the ovary and is transported by the oviducts. This causes the uterine cycle, or menstrual cycle.
The menstrual cycle consists of an average time frame of twenty-eight days that contains three phases. The first phase, called menstruation, causes the endometrium (lining of the uterus) to disappear and its blood vessels to rupture. This creates a passing of these tissues out of the vagina in a form of blood that makes it the menstrual period. The menstrual period usually lasts up to five days. The second phase, called the proliferative phase, allows for the endometrium to rebuild from the increase of estrogen hormones by a developing oocyte. This phase occurs after menstruation ends and can last up to day thirteen of the cycle. And, the last phase, called the secretory phase, causes the increase in the hormone progesterone by the developing ovary. This creates the thick, membranous buildup of the endoterinum and the secretion of thick mucous for the receiving of the developing embryo. But, if the egg is not fertilized, the process occurs again. Along with the method of a vasectomy of males, there are other ways to prevent pregnancy.
There are several different birth control options. They consist of: the intrauterine device, the diaphragm and spermicidal jelly, female condom, male condom, implant, injections, vaccines, and oral contraceptive. The intrauterine device is a small piece of structured plastic that is placed within the uterus by a healthcare professional. It alters the overall internal environment of the uterus and the oviducts that lower the chances of fertilization taking place, but if fertilization does happen, the egg cannot implant due to the appearance of the device. The diaphragm is a soft cup that fits over the cervix and is wedged behind the pubic bone (must be fitted by a healthcare professional). Spermicidal jelly is added to its external features to kill any sperm that try to pass the barrier. The female and male condoms are polyurethane and latex sheaths that are either inserted in the vagina (female condom) or placed over an erect penis (male condom). The ring of the female condom fits over the opening of the cervix to prevent any entry of semen and the male condom catches the ejaculated semen within it. An implant uses synthetic female hormones to, “…prevent ovulation by disrupting the ovarian cycle” (Mader 332). They are surgical placed underneath the skin of a woman’s arm and can last as long as three years. Injections consist of synthetic combinations of female hormones that prevent the chances of pregnancy and are applied from a few weeks to every three months. Vaccines, which are newly developed, are intended to immunize women against the hormone needed to allow for implantation of an embryo. And, oral contraceptives are medications that are taken to reduce the chance of pregnancy. Unfortunately, the occurrence of sexually transmitted diseases hinders the practicality of safe sexual intercourse.
Sexually transmitted diseases consist of two types of diseases. One type is the viral diseases that cannot be treated with antibiotics. Some viral diseases consist of HIV infections, genital warts, genital herpes, and hepatitis. Another type is the bacterial diseases that can be treated with antibiotics, but can leave debilitating effects on the body later in life. Some bacterial diseases are Chlamydia, gonorrhea, and syphilis. All of these sexually transmitted diseases, whether they are viral or bacterial, have very negative side effects to the human body, especially the STD hepatitis.
The sexually transmitted disease, hepatitis, is an infection of the liver that can, “…lead to liver failure, liver cancer, and death” (Mader 337). And, there are six different types of hepatitis such as, A, B, C, D, E, and G. The most common form of hepatitis that is transmitted by sexual contact and blood is hepatitis B. And unfortunately, hepatitis B, “…persists for decades after patients’ recovery from acute viral hepatitis despite active maintenance of (T-cells)” (www.nature.com/nm/wilma/v2n10.861158388.html).

Figure 3: Visual of the sexually transmitted disease Hepatitis B

There are also other common infections of the reproductive tract.
There are three types of infections that can also occur within the reproductive tract. The first is bacterial vaginosis that is caused by disruption of healthy bacteria in the vagina. This leads to overgrowth of certain bacteria and causes 50% of vaginitis in American women. The second is trichomoniasis that is caused by a flagellated protozoan. This leads to symptoms of a frothy discharge, itching, and foul smell. Also, this infection is another common cause of vaginitis. And, the last is candidiasis that is caused by overgrowth of yeast in the vagina. This leads to symptoms of red, inflamed, and itchy external genitalia and a white, curdy discharge. Also, women are prone to this infection from the use of birth control and antibiotics. Along with birth control options, there are also options that help protect against sexually transmitted diseases.
There are four major ways that individuals can protect themselves against STDs. The first way is the choice of abstinence. This is the choice of abstaining from sexual intercourse with a partner and is the best way to prevent transmission of diseases sexually. The second way is developing a long-term monogamous relationship. The third way is creating awareness to whether or not a partner uses intravenous drugs. This knowledge is important, because IV users have a higher rate of contracting STDs from sharing needles with other users. And the forth way is practicing safer safe by using condoms, avoiding oral sex, cleanliness of the reproductive tract, and limiting use of drugs or alcohol that reduces inhibitions and logical thinking. Along with meiosis being a major event of the human life cycle, there are also several others that have significance.

Two major events that occur within the reproductive system of females are that of fetal development and birth. The process for which fetal development can occur begins with the process of fertilization and implantation. Fetilization happens in a series of five steps. In the first step, the sperm navigates it way through the egg's exterior, adhering cells. Then, the sperm's external enzyme caseing breaks down the adhering cells and is able to finally fuse with the egg's internal membrane. The third step consists of the sperm's nucleus entering the cytoplasm of the egg and the outside of the egg releases fertilization enzymes. Lastly, the nucleus of the sperm and egg join together into a nuclear envelope.
After fertilization occurs, the cell begins mitosis, which allows for the cells to repeatedly multiply. Then, it passes down the oviduct and into the uterus for implantation. During implantation, the egg becomes a part of the uterine wall for proper future growth. But, an ectopic pregnancy can happen, which the egg implants itself somewhere besides the uterus. When this does happen, emergency surgery must take place in order for the body not to experience internal hemorrhaging. Then the process of embryonic development occurs, if implantation is successful.
Embryonic development happens within the first couple months of pregnancy. The embryo implants itself within the uterian walls and begins developing the embryonic disk, which contains membranes for blood cell formation, the nervous system, all the major body systems, glands of these body systems. These systems are also laid out in fetal germ layers that resemble early fetal form from the future adult body. Also, the amniotic fluid develops, that protects the embryo. After the membranes have fully developed, the actual start of the heart and nervous system appear. Then, towards the end of the second month of gestation, the umbilical cord connects to the placenta, little limbs begin to pop out of the embryo, sense organs are more defined, and the embryo begins to resemble a human being. After the development of the embryo, fetal development occurs.
Figure 4: The stages of embryonic development

Fetal development is the continuing maturation of the forthcoming individual that occurs from month three to month nine. The second trimester, which includes months four, five and six, has many developments in the fetus. For example, the, “…muscles begin to develop and sex organs form…and the child’s spontaneous movements can be observed” (www.wprc.org/parenting/fetal-development/). Also, the fetus learns how to grasp, seat glands develop, and the skin changes from a transparent appearance to an opaque appearance. The third trimester, which includes months seven, eight, and nine, has many more developments in the fetus. For example, the baby learns to use its lungs by inhaling and exhaling and the eyes are completely formed. At the end of gestation, which is the end of the third trimester, development is complete and the fetus is ready to live outside the female’s uterus. Pregnancy for females also creates new developments for internal and external anatomy.
There are several changes that happen to female anatomy. The internal organs of the bladder, rectum, and stomach are pushed superiorly and compressed. This leads to changes in urination, defecation, and eating patterns. For example, pregnant women tend to urinate more often, have repeated occurrences of constipation, and eat more often, but ingest smaller amounts of food at each meal. The immune system within the female body also changes. The immune response creates an environment of protection for the fetus by changes in appetite. This possibly creates avoidance of poisons in foods that can harm the baby.

Figure 5: The changes in female anatomy due to pregnancy

The external anatomy of a pregnant woman also changes. The posture of an individual changes due to anterior weight. This allows for appropriate compensation for the developing baby and the pregnant woman. Also, the breasts enlarge from the production of early milk, called colostrum. After fetal development is complete, then the process of birth occurs.
Another major event of the human life cycle is birth. At a biological standpoint, birth occurs in three stages. In the first stage of labor (process of birth), contractions of the uterus occur. These contractions allow for the cervix to dialate and disappear, which is called effacement. And, with continuing contractions, the baby head, “…acts as a wedge for cervical dilation” (Mader 369). Once the cervix has completely dilated, the second stage occurs. In the second stage of labor, the desire to push the baby through the birth canal is very great, due to the repetitive contractions. And, as the head of the baby continues to slowly enter the birth canal, the urge to push is even greater. Once the pushing stage has been completed, the head of the baby is delivered, along with the helping guide (by the physician or midwife) of the shoulders, and the rest of the baby. Generally, once the baby is breathing effectively, the umbilical chord that connected the baby to the placenta is cut. Once the baby is delivered, the third stage occurs. In the third stage of birth, the placenta is delivered several minutes after the baby is born. The uterus begins to contract again and the placenta is delivered through the vagina. As soon as this happens, the process of birth is finished. In accordance with the process of birth, there are several different approaches to birthing and child-raising.
There are many different approaches to the birthing process. Some processes include, natural birth, hospital birth, cesarean birth, etc. In my personal experiences with birth, I chose to have my daughter naturally in the environment of my home with a licensed midwife. During my labor, I used several different techniques like breathing, relaxation, massage, swaying, low-lighting, silence, walking, squatting, and warm water. I had originally planned to have a water birth, but I became so relaxed that the warm water was slowing down my contractions! So, I ended up giving birth to my daughter on our bed. Once she was born, she was immediately placed on my bare chest and the umbilical chord was not cut until it stopped pulsing, which my husband took the liberty of doing. Also, my mother and mother-in-law were also there to provide me with support during labor and birth. My birth story was an incredible experience! I was so lucky to able to experience my labor and birth in the most natural ways possible (in the United States). I was able to appreciate the birth of my daughter in an entire new realm, because I was able to push through whatever pain I was experiencing during labor and birth. She gave me power, strength, determination, spiritual enlightenment, and absolute love. There are also many different approaches to child-raising that leads to human populations and evolution.

I was shocked when I first realized that I was going to become a parent, but, when I look upon the past today, I am so blessed that the choices I had made has given me such a beautiful and amazing spirit. She has shown a new world to me through different eyes, giving the purpose and drive for my life. And, my daughter has made me into such an empowered individual. In accordance with Human Biology, the different processes of reproduction are very important to the continuation of life, not only on a spiritual level but on a biological level as well. There are three major parts of life that contribute to reproduction, which are: the human life cycle, meiosis (eggs and sperm), and fetal development and birth. The human life cycle consists of: meiosis, fertilization, fetal development, birth, childhood/adolescence, adulthood (meiosis), aging, and death. The event of meiosis happens within the reproductive systems of both males and females, called spermatogenesis and oogenesis. But, it only occurs in females if an egg is fertilized by a sperm, and if that does not occur, a normal menstrual cycle will take place. There are several birth control options to choose from such as: vasectomy, intrauterine devices, diaphragm, condoms, oral contraceptives, implants, and vaccines. And unfortunately, sexual intercourse can lead to sexually transmitted diseases like, hepatitis B, if individuals do not take proper prevention of STDs. The events of fetal development and birth begin with fertilization of an egg by a sperm that leads to implantation and early embryonic development. Then, fetal development occurs from month three to month nine, creating important internal and external features within the fetus and changing the internal and external anatomy of the pregnant female. The process of birth occurs after fetal development is complete in three stages. And, there are many different approaches to birthing and child-raising. In the end, it affects the outcomes of populations and their evolutions.

Sources:
Works:
Human Biology, 10e. Mader, Sylvia S.
www.wprc.org/parenting/fetal-development/
www.nature.com/nm/wilma/v2n10.861158388.html
Pictures:
health.yahoo.com/.../r7_malerepro.jpg
medpics.findlaw.com/imagescooked/7343W.jpg
www.cs.nyu.edu/els4/prevwk/prev/HepatitisB.jpg
embryology.med.unsw.edu.au/.../Images/Cst800.jpg
www.waukeshamemorial.org/.../anatomy.gif