16.1 Human Life Cycle
16.2 Male Reproductive 16.3 Female Reproductive System
16.4 Female Hormone Levels
16.5 Control of Reproduction
16.6 Sexually Transmitted Disease
16.1 Human Life Cycle
Male and females have quite different reproductive systems.
Sexual maturity is called puberty, it occurs in females a earlier, usually between ages 11-13 and in males, between 14-16.
Reproductive organs are called genitals.
Males-
(1) sperm is produced in testes
(2) sperm are transported in ducts and exit the male through the penis
(3)the penis delivers sperm to a females vagina
(4) testes produce sex hormones for masculization.
Females-
(1) eggs are produced within ovaries
(2)eggs are transported in uterine tubes to the uterus
(3) the vagina receives sperm from the male, transports menstrual flow out of the body, is the birth canal
(4) Fertilized eggs develop in the uterus, breasts produce milk for the newborn after birth.
(5) ovaries produce sex hormones for feminization and pregnancy.
Mitosis and Meiosis
Mitosis is “duplication division” of the 46 chromosomes within the nucleus.
Mitosis takes place in the life cycle of a human during times of growth and repair.
Meiosis is a type of cell division in humans that is referred to as “reduction division”.
It is very specific in its occurrence, in males it only takes place during the production of sperm and in females during production of eggs.
Meiosis reduces the chromosome count of 46 (diploid) in half to 23 (haploid).
In meiosis there are two cell divisions, called meiosis I and meiosis II.
The small flagellated sperm is specialized to carry chromosome to the egg. The egg is specialized in its waiting for sperm to bring chromosomes and also it provides cytoplasm as well as chromosomes.
The zygote ends up with 46 chromosomes because the sperm provides 23 and the egg provides 23.
Meiosis is the reason why the newly formed “zygote” ends up with 46 total chromosomes:
without meiosis, the zygote would end up with 92 chromosomes, 46 from the sperm and 46 from the egg.
16.2 Male Reproductive System
The primary sex organs in the male are the paired testes (gonads) suspended in sacs of the scrotum
The following are the male reproductive organs:
Testes- produce sperm/sex hormones
Epididymides-ducts for sperm storage and maturation
Vasa deferentia- conduct and store sperm
Seminal vesicles- contributes nutrients and fluid to semen
Prostrate gland- contributes fluid to semen
Urethra- conducts sperm
Bulbourethral glands- contribute mucus- containing fluid to semen
Penis- organ for sexual intercourse
Seminal fluid is made of ingredients that have functions toward reproduction.
Orgasm in Males:
Penis has long shaft with enlarged tip called glans penis, which is covered by foreskin, unless circumcision has taken place. Circumcision is the surgical removal of the foreskin, typically done when the male is still an infant.
During sexual arousal autonomic nerves release nitric oxide,NO. This stimulus leads to CGMP
production, next the smooth muscle walls relax, which leads to the erectile tissues to fill with
blood. An erection occurs because the blood vessels that carry blood away are compressed.
Erectile dysfunction occurs when the expansion of the penis is not enough to compress the veins.
Contractions expelling seminal fluid are part of male orgasm. Orgasm includes psychological and
physiological satisfaction. Refractory period is the time after orgasm when the penis returns to
normal size and there is a loss of sexual arousal. As a male ages the refractory period lengthens.
During ejaculation there may be up to 400 million sperm in semen.
The hypothalamus plays a vital role in sexual function because it secretes and regulates hormones.
Testosterone is the main male sexual hormone. It is responsible for normal development,
secondary sexual characteristics and greater muscular development.
16.3 Female Reproductive System
The female sexual organs include:
Ovaries-which produce eggs and hormones
Oviducts- which conduct eggs, location of fertilization (uterine or fallopian tubes)
Uterus (womb)- which houses the developing fetus
Cervix- is the opening to the uterus
Vagina- which receives the penis, serves as the birth canal and is the exit for menstrual flow.
Eggs are stored in the ovaries and when an egg is released it travels down the fallopian tube
toward the uterus. The egg can live approximately 6-24 hours and unless it becomes fertilized
(usually in the fallopian tube) by a sperm, then it does not become implanted in the uterine wall.
Implantation occurs when an egg becomes fertilized and then a zygote is formed.
An egg is usually released once a month, fertilization occurs in the oviduct (fallopian tube) and
development takes place in the uterus.
External female genitals are called the vulva. Included are two folds of skin called the labia
majora, labia minora, mons pubis, and clitoris, which is the female equivalent to the male penis,
as it is the organ of sexual arousal.
Orgasms in Females
Sexual stimulation occurs and the labia minora, vaginal wall and clitoris become engorged with
blood-the vagina expands and elongates, the vagina becomes lubricated. Orgasm occurs at
height of sexual response and the walls of the uterus contract rhythmically. Females require no
refractory (resting time) and can experience multiple orgasms in one sexual encounter.
16.4 Female Hormone Levels
Follicles are inside the ovary and each follicle contains an immature egg. Only a small number of the follicles are ever used during the reproductive years of a female because typically only one egg is released every month.
The ovarian cycle is as follows:
1-Primary follicle contains oocyte and produces estrogen
2-Secondary follicle contains secondary oocyte and produces estrogen and some progesterone
3-Graafian develops
4- Ovulation-secondary oocyte released
5-Corpus Luteum makes progesterone and some estrogen
6-Corpus Luteum degenerates
The hypothalamus controls the hormones responsible for sexual function in the female just like in the male.
Estrogen is responsible for secondary sex characteristics.
Estrogen and progesterone affect the uterus and breast development and also milk production.
The pelvic girdle is typically wider in females.
Menopause os when the ovarian cycle ceases in a woman’s life. Menstruation becomes irregular and then ceases.
Twenty-eight cycles of the Uterine Cycle are as follows:
Days 1-5/Low level of estrogen and progesterone
Days 6-13/increase production of estrogen
(Days 1-13) FSH secretion begins/follicle maturation occurs/estrogen secretion is prominent
Day 14/ ovulation usually occurs
(Day 14) LH spike occurs
Days 15-28/increase production of progesterone
(Day 15-28) LH secretion continues/corpus luteum forms/progesterone secretion is prominent.
Fertilization and Pregnancy
If an egg becomes fertilized with a sperm then the endometrium will receive the zygote and it becomes implanted in the lining.
The placenta sustains the developing embryo and later the fetus. It produces HCG/In time the placenta produces progesterone and some estrogen.
16.5 Control of Reproduction
Birth control is used to prevent pregnancies.
Abstinence is the best way and simply means to abstain from sex. Some other effective birth
control methods are: IUD, hormone skin patch, Depo-Provera, diaphragm, female condom, Male condom, and oral contraception.
The morning after pill is an emergency contraceptive and consists of four hormones, it blocks the progesterone receptor proteins and causes the bodily loss of the implanted embryo.
Infertility means the failure to achieve pregnancy.
Low sperm count or abnormal sperm can be cause, female obesity can cause.
Artificial Insemination can be used to implant sperm in female to impregnate egg.
In Vitro Fertilization can be used to conceive in laboratory and then implant within the female uterus.
Gamete Intrafallopian Transfer can be used and is more successful than IVF.
Surrogate Mothers, paid women usually to carry the parents sperm and egg.
16.6 Sexually Transmitted Disease
HIV- sexually transmitted disease (STD) AIDS is the last stage of the HIV virus.
38.6 million people are thought to be infected with HIV worldwide and 25 million people have died from AIDS.
HIV compromises the persons immune system and it is typically an opportunistic infection that kills the person, not the actual virus. There is no cure for AIDS but there is an antiretroviral therapy that can stop HIV reproduction.
Genital Warts-caused by HPV- often carriers do not show signs- genital warts are associated with cervical cancer and at this time there is a vaccine for warts which is exciting for the potential help with cervical cancer.
Genital Herpes- caused by the herpes simplex virus-Type I associated with cold sores/ Type II associated with genital herpes. Type II usually occurs during adulthood- Can cause neurological disorders in newborns and even lead to death.
Hepatitis- infects the liver, can lead to liver failure, cancer, and death.
There are 6 virus’ that cause hepatitis (A,B,C,D,E,G)
STD’s Caused by Bacteria
These types of sexually transmitted diseases can be cured with antibiotics.
Chlamydia/ infection of the lower reproductive tract.
Gonorrhea- in men a urethral discharge of thick, greenish-yellow. In men and women it leads to
pelvic inflammatory disease, can cause sterility in males.
Syphilis- has three stages, in third stage will cause death. When the bacteria crosses the placenta
it will cause blindness in the newborn.
Health focus on page 339
This article focuses on ways to avoid contracting STD’s. Abstinence is the best way to avoid any
This article focuses on ways to avoid contracting STD’s. Abstinence is the best way to avoid any
STD’s. Multiple sex partners and choosing to have sex with people who have multiple sex
partners is risky. Bisexuals and homosexuals have higher rates of HIV virus in population so
protection and awareness are important. Unprotected sex with IV drug users is risky as is anal
sex.
Chapter 17/ Developing and Aging
17.1 Fertilization
17.2 Pre- Embryonic and Embryonic Development
17.3 Fetal Development
17.4 Pregnancy and Birth
17.5 Development After Birth
17.1 Fertilization
The union of a sperm and an egg is called fertilization. This union forms a zygote.
1- Sperm makes its way through the corona radiata.
2- Acrosomal enzymes digest a portion of zona pellucida.
3- Sperm binds to and fuses with egg plasma membrane.
4- Sperm nucleus enters cytoplasm of egg.
5- Cortical granules release enzymes; zona pellucida becomes fertilization membrane.
6- Sperm and egg pronulclei are enclosed in a nuclear envelope.
17.2 Pre- Embryonic and Embryonic Development
Computer generated imagery of DNA double-helix with methylation. The very beginnings of life-DNA :Genetic Blueprint
Processes of Development
Cleavage- the zygote begins to divide immediately after fertilization. Cell division is miotic and the zygote receives full set of chromosomes and genes.
Growth- Cell division increases in size of daughter cells.
Morphogenesis- Refers to shaping of the embryo and movement along with migration of certain cells.
Differentiation- Refers to specific structure and function of cells, which occurs first in the nervous system.
Extraembryonic Membranes are located outside the embryo. The function of the
Extraembryonic Membranes in human beings is specific to the species because humans develop in the uterus.
(1)Chorion- this is the fetal half of the placenta after development (the placenta is organ that nourishes and carries waste)
(2)Allantois- accumulates urine
(3)Yolk Sac- it is the first site of blood cell formation
(4)Amnion- contains fluids to cushion and protect
280 days is considered “normal gestation period” mathematically it is figured as: 280 days added to the start date of the last menstruation cycle.
Pre-embryonic Development- (first week) sperm enters egg and fertilization occurs in the fallopian tube…..as zygote moves along the oviduct cleavage occurs to produce morula, also the blast cyst forms and lodges into the lining of the uterus.
Embryonic Development-(second week till end of 8th week) the umbilical cord takes shape- gastrulayion begins
17.3 Fetal Development
Progesterone and estrogen are produced by the placenta during a pregnancy and these two
hormones along with negative feedback from the hypothalamus and pituitary no new follicles can
mature- the hormones also prevent any further menstruations during pregnancy.
Path of fetal blood travels through the umbilical cord. At the placenta there is an exchange of
molecules between fetal and maternal blood across the walls of the chorionic villi.
Science Focus page 362 / Cloning Humans: Can it be Done?
1997 was the first successful cloning experiment and although today we consider cloning of animals to be fairly commonplace, there are still a number of problems associated with it.
(1) A large number of the pregnancies are not successful because they do not end in full term live births.
(2) Abnormalities with the clone’s growth are common.
(3) Often spontaneous abortion occurs.
(4) Typical abnormalities occur.
(5) Appearance may look normal however disease and other difficulties soon arise often times.
There are two types of cloning:
Reproductive Cloning is when the end result is an individual-
Therapeutic Cloning is when the desired outcome is embryonic cells that can then be shaped genetically into various cell types.
Events of Fetal Development (3rd through the 9th month) During the 3rd and the 4th month
The fetus can be recognized as a human being. During this stage of development many changes are taking place with the fetus head development. During this stage it becomes possible to detect the sex of the fetus. The babies heartbeat becomes strong and can be detected with a stethoscope.
During the 5th through the 7th month
Movement can now be felt by the mother.
The fetus skin is covered by fine down (like fur).
Eyelids are open.
The baby stands a chance of survival if it is born at this time during the pregnancy.
During the 8th and the 9th month
Baby will be about 20 ½ inches long and weigh about 7 ½ lbs prior to birth. Head is usually pointed toward the cervix to emerge into the world head first through the birth canal. A baby born feet first is calle3d “breech’’.
The sex of a child is actually determined at the moment of fertilization. Males = chromosomes X+Y….Females = X+X
There is no way to differentiate the sex of a fetus externally during the first few weeks of pregnancy. If SRY genes are present in the genetic make up then the script is for male genitals but w/o SRY genes then the code is for female sex organs.
17.4 Pregnancy and Birth
Placental hormones (estrogen and progesterone) are responsible for physical changes of the mother during pregnancy. During pregnancy a woman goes through many physiological changes.
Energy level changes, body weight, nausea, and back pain.
Placental hormones in the mothers body support the growth and well being of the fetus. Some of the changes are: arteries relax, changes in blood pressure, blood volume increases, cardiac output increases, decrease in intestinal tract motility.
The pulmonary values increase and also, bronchial tubes relax, uterus size increases, and blood carbon dioxide levels drop significantly. Compression of the ureters and bladder can cause incontinence. Stretch marks often times occur.
Birth
Braxton Hicks Contractions are “false labor” contractions.
“Parturition” refers to the process of giving birth to offspring
Stage 1 Labor: the cervical canal disappears as the lower part of uterus is pulled upward toward the baby’s head when the uterus is contracting (this phase is called affacement) the baby’s head acts as a wedge- amniotic fluid usually ruptures during this stage-this stage is complete once the cervix dilates completely.
Stage 2 Labor: during this stage of labor the physical desire to push increases greatly as the contractions become stronger and also closer together. The baby travels down the birth canal and once the head emerges then the rest of the body follows more easily- the umbilical cord is cut once the baby starts breathing.
Stage 3 Labor: The placenta is delivered and then the birth cycle is complete.
17.5 Development After Birth
Aging refers to the continuation of development that naturally occurs in the life cycle and can lead to disease and death.
Gerontology is the study of aging.
Hypotheses of Aging
Genetic in Origin: It is believed that aging has a genetic basis/ defective mitochondrial (defective DNA polymere) may accelerate the process of aging.
Whole Body Process: A decline in the hormonal system function causes aging/diabetes type 2 and menopause occur in older adults because cell receptors are ineffective. The immune system does not function as well in older adults as it does in younger ones. Aging may or may not be caused by system failures. Cross linking of proteins that support tissues may increase the organ break down process and promote the aging process. Cross linking may also explain the inability of certain organs, such as the heart, lungs, and blood vessels to operate in latter life the same way that they operate in younger people. Elasticity in tendons and ligaments decreases with aging, which is another by product of cross linking.
Glucose attaching to the protein molecules in a persons body is the first step in cross linking.
Extrinsic Factors: It may come to light someday that the actual signs of aging are caused in large part to years and years in early life of lack of good diet and exercise.
Skin becomes thinner as people age.
The homeostasis system does not adjust to or tolerate heat in the older person.
Cardiovascular disease are leading cause of death in the older adult population.
Blood flow to liver is decreased as is the flow to the kidneys.
Loss of teeth is more due to neglect than to aging. Brain function for learning and retention is slower but still quite functional.
Loss of skeletal muscle is common, as is weight gain.
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