Unit 4 Compendium 1- Reproduction

Table of Contents

I. Reproductive System
A. Human Life Cycle
B. Male Reproductive System
C. Female Reproductive System
D. Female Hormone Levels
E. Control of Reproduction
F. Sexually Transmitted Diseases
II. Development and Aging
A. Fertilization
B. Pre-Embryonic and Embryonic Development
C. Fetal Development
D. Pregnancy and Birth
E. Development After Birth



I. Reproductive System
A. Human Life Cycle
1. The life cycle of higher organisms, such as humans, requires two types of cell division.
a. Mitosis- growth and repair of tissues; 46 chromosomes in each cell.
b. Meiosis- gamete production; reduces from 46 to 23 chromosomes in each cell.
B. Male Reproductive System
1. The external genitals of males are:
a. Penis- organ for sexual intercourse.
b. Scrotum- contains the testes.
2. Spermatogenesis, occurring in seminiferous tubules of the testes, produces sperm.
a. Mature sperm are stored in the epididymides.
b. Sperm pass from the vasa deferentia to the urethra.
c. The seminal vesicles, prostate gland, and bulbourethral glands add fluids, by secretion, to sperm.
d. Sperm and secretions are called semen or seminal fluid.
3. Orgasm in males results in ejaculation of semen from the penis.
4. Hormone Regulation in Males
a. Hormone regulation, involving secretions from the hypothalamus, the anterior pituitary, and the testes, maintains a fairly constant level of Testosterone.
b. FSH from the anterior pituitary promotes spermatogenesis.
c. LH from the anterior pituitary promotes Testosterone production by interstitial cells.
C. Female Reproductive System
1. Oogenesis occurring within the ovaries typically produces one mature follicle each month.
a. The follicle balloons out of the ovary and bursts, releasing an egg that enters an oviduct.
b. The oviducts lead to the uterus, where implantation and development occur, if the egg is fertilized.
2. The female external genital area includes: the vaginal opening, the clitoris, the labia minora, and the labia majora.
a. The vagina is the organ for sexual intercourse and the birth canal in females.
3. Orgasm in females culminates in uterine and oviduct contractions.
D. Female Hormone Levels
1. Ovarian Cycle: Non Pregnant
a. The ovarian cycle is under the hormonal control of the hypothalamus and the anterior pituitary.
b. During the cycle's first half, FSH from the anterior pituitary causes maturation of a follicle that secretes Estrogen and some Progesterone.
c. After ovulation and during the cycle's second half, LH from the anterior pituitary converts the follicle into the corpus luteum.
d. The corpus luteum secretes Progesterone and some Estrogen.
2. Uterine Cycle: Non Pregnant
a. Estrogen and Progesterone regulate the uterine cycle.
b. Estrogen causes the endometrium to rebuild.
c. Ovulation usually occurs on day 14 of a 28 day cycle.
d. Progesterone produced by the corpus luteum causes the endometrium to thicken and become secretory.
e. A low level of hormones causes the endometrium to break down as menstration occurs.
3. Fertilization and Pregnancy
a. If fertilization takes place, the embryo implants itself in the thickened endometrium.
b. The corpus luteum is maintained because of HCG production by the placenta, and therefore, Progesterone production does not cease.
c. Menstration usually does not occur during pregnancy.
E. Control of Reproduction
1. Numerous birth control methods and devices are available:
a. Intrauterine Device (IUD), Hormone Skin Patch, Depo-Provera, Diaphram with Spermicidal Jelly, Female Condom, Male Condom, Implant, Oral Contraceptive (the pill), Cervical Shield or Cap, Morning-After Pills, Vaginal Ring, Douching, Withdrawal Method, Natural Family Planning, Abstinence.
b. Effectiveness of each varies.
2. Assisted reproductive technologies may help infertile couples to have children. Some of these technologies are:
a. Artificial Insemination by Donor (AID)
b. In-Vitro Fertilization (IVF)
c. Gamete Intrafallopian Transfer (GIFT)
d. Intracytoplasmic Sperm Injection (ICSI)
F. Sexually Transmitted Diseases (STDs) are caused by viruses, bacteria, protists, fungi, and animals.
1. STDs caused by viruses:
a. AIDS is caused by the Human Immunodeficiency Virus (HIV).
b. Genital Warts are caused by the Human Papillomavirus (HPV); these viruses cause warts or lesions on genitals and are associated with certain cancers.
c. Genital Herpes is caused by the Herpes Simplex virus type II; causes blisters on genitals.
d. Hepatitis is caused by Hepatitis visuses A, B, C, D, E, and G. A nad E are usually aquired from contaminated water, B and C from bloodborne transmission, and B,D, and G are sexually transmitted.
2. STDs caused by bacteria:
a. Chlamydia is caused by Chlamydia Trachomatis; PID can result.
b. Gonorrhea is caused by Neisseria Gonorrhoeae; PID can result.
c. Syphilis is caused by Treponema Pallidum; has three stages, with the third resulting in death.
3. Two Other Infections:
a. Bacterial Vaginosis is caused by Gardnerella Vaginalis.
b. Trichomoniasis is an overgrowth of Candida Albicans.
II. Development and Aging
A. Fertilization
1. A single sperm is drawn into the egg by microvilli of its plasma membrane. With the help of enzymes from the acrosome, a sperm makes its way through the zona pellucida. After a sperm binds to the plasma membrane of the egg, changes occur that prevent other sperm from entering the egg. Fertilization is complete when the sperm pronucleus and the egg pronucleus contribute chromosomes to the zygote.
B. Pre-Embryonic and Embryonic Development
1. Processes of Development.
a. Cleavage- Immediately after fertilization, the zygote begins to divide so that there are first 2, then 4, 8, 16, and 32 cells, and so forth. Increase in size does not accompany these divisions. Cell division during clevage is mitotic, and each cell recieves a full complement of chromosomes and genes.
b. Growth- during embryonic development, cell division is accompanied by an increase in size of the daughter cells.
c. Morphogenesis- refers to the shaping of the embryo and is first evident when certain cells are seen to move, or migrate, in relation to other cells. By these movements, the embryo begins to assume various shapes.
d. Differentiation- when cells take on a specific structure and function, differentiation occurs. The first system to become visibly differentiated is the nervous system.
2. The extraembryonic membranes (chorion, allantois, yolk sac, and amnion) function in internal development.
C. Fetal Development
1. At the end of the embryonic period, all organ systems are established, and there is a mature and functioning placenta.
2. The umbilical arteries and umbilical vein take blood to and from the placenta, where exchanges take place.
a. Exchanges supply the fetus with oxygen and nutrients and rid the fetus of carbon dioxide and wastes.
b. The venous duct joins the umbilical vein to the inferior vena cava.
c. The oval duct and arterial duct allow the blood to pass through the heart without going to the lungs.
3. Fetal development extends from the third through the ninth month.
a. During the third and forth month, the skeleton is becoming ossified.
b. The sex of the fetus becomes distinguishable. If an SRY gene is present, testes and male genitals develop. Otherwise, ovaries and female genetals develop.
c. During the fifth through the ninth month, the fetus continues to grow and to gain weight.
D. Pregnancy and Birth
1. Major changes occur in the mother's body during pregnancy.
a. Weight gain occurs as the uterus occupies most of the abdominal cavity.
b. Constipation, heartburn, darkening of certain skin areas, and pregnancy-induced diabetes, are due to the presence of placental hormones (hCG).
2. Birth
a. Apositive feedback mechanism that involves uterine contractions and oxytocin explains the onset and continuation of labor.
b. During stage one of parturition (birth), the cervix dilates.
c. During stage two, the child is born.
d. During stage three, the afterbirth is expelled.
E. Development After Birth- consists of infancy, childhood, adolescence, and adulthood.
1. Aging encompasses progressive changes, from about age 20 on, that contribute to an increased risk of infirmity, disease, and death.
2. Hypotheses of Aging
a. Aging may have a genetic basis.
b. Aging may be due to changes that affect the whole body (ex: decline of hormonal system).
c. Aging may be due to extrinsic factors (ex: diet and exercise).
3. Effect of age on body systems:
a. Deterioration of organ systems can possibly be prevented or reduced by utilizing good health habits.