Thursday, July 10, 2008

Compendium Review Unit 4 Major Topic: Reproduction

I. Reproductive System
A. Human Life Cycle
B. Male Reproductive System
C. Female Reproductive System
E. Female Hormone Levels
F. Control of Reproduction
G. 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. Functions of reproductive organs
a. production
b. transport
c. delivery
d. fertilization, nourishment
e. hormones
2. Mitosis and meiosis
a. mitosis - duplication division for growth and repair, diploid # 46 chromosomes
b. meiosis - reduction division, to produce sex cells, haploid # 23 chromosomes
B. Male Reproductive System
1. Organs - testes, epididymides, vasa deferentia, seminal vesicles, prostate gland, urethra, bulbourethral glands, penis - see definitions for functions
Figure 16.2 from the text illustrates the male reproductive system
2. Orgasm in males
a. nitric oxide release leads to production of cGMP (cyclic guanosine monophosphate)
b. cGMP cuases smooth muscle of incoming arterial walls to relax
c. erectile tissue fills with blood
d. outgoing venous walls compress, erection
e. sperm enter urethra from each vas deferens, glands contribute secretions
3. Male gonads, the testes
a. seminiferous tubules - location of spermatogenesis, Sertoli cells
b. interstitial cells - lie between seminiferous tubules, secrete androgens
Figure 16.4 from the text depicts the testis and sperm and spermatogenesis.
4. Hormonal regulation in males
a. hypothalamus secretes GnRH
b. GnRH stimulates anterior pituitary to secrete gonadotropic hormones (FSH, LH)
c. GnRH, FSH, LH involved in neg feedback relationship - maintains constant production of sperm and testosterone
C. Female Reproductive System
1. The genital tract
a. egg - ovary->fimbriae->cilia/oviduct->uterus, lives 6-24 hrs unless fertiized
b. fertilization (zygote formation) usually takes place in oviduct
c. implantation after several days
d. uterus, endometrium, cervix, vagina
Figure 16.6 from the text illustrates the female reproductive system.
2. External genitals vulva: labia majora, mons pubis, labia minora, glans clitoris, urethra, vagina
3. Orgasm in females
a. labia minora, vaginal wall, clitoris engorge with blood
b. blood vessels in vaginal wall & mucus-secreting glands beneath labia minor secrete lubricating fluid
D. Female Hormone Levels
1. Ovarian cycle (phases): nonpregnant
a. hypothalamus secretes GnRH
b. GnRH stimulates anterior pituitary to secrete gonadotropic hormones (FSH, LH)
c. FSH & LH not present in constant amounts, secreted at different rates during cycle
d. follicular phase - FSH promotes development of follicles that secrete estrogen
e. estrogen level in blood provides neg feedback to ant pituitary secretion of FSH - ends follicular phase
f. spike in estrogen - large amt of GnRH secreted - surge of LH - ovulation day 14
g. luteal phase - LH promotes development of corpus luteum - secretes progesterone
Figure 16.8 from the text illustrates the ovarian cycle and shows oogenesis.
2. Estrogen and progesterone
Figure 16.10 from the text shows the female hormone levels during a complete menstrual cycle (no pregnancy).
3. Uterine cycle: nonpregnant
4. Fertilization and pregnancy
a. fertilization occurs in oviduct
b. pregnancy begins when developing embryo implants in endometrium
c. placenta produces HCG which stimulates corpus luteum to produce more progesterone
d. progesterone shuts down hypothalamus & anterior pituitary - prevent new follicles from beginning
Figure 16.11 shows the effect of pregnancy on female hormone levels.
E. Control of Reproduction
1. Birth control methods
a. abstinence
b. contraceptives - birth control pill, IUD, diaphragm, female & male condums, implants, injections, vaccines
c. vasectomy and tubal ligation
d. morning after pills
2. Infertility
a. causes
i. male - low sperm, abnormal sperm=temperature, sedentary, smoking, alcohol
ii. female - body weight=small follicles; blocked oviducts=pelvic inflammatory disease, endometriosis
b. assisted reproductive technologies
i. artificial insemination by donor (AID), intrauterine insemination (IUI)
ii. in vitro fertilization (IVF)
iii. gamete intrafallopian transfer (GIFT)
iv. surrogate mothers
v. intracytoplasmic sper injection (ICSI)
F. Sexually Transmitted Diseases
1. STDs caused by viruses
a. HIV infections - primary host is helper T lymphocyte, immune system becomes severly impaired, treatment=HART
b. genital warts caused by human papillomaviruses
c. genital herpes caused by herpes simplex virus
d. hepatitis infects the liver
2. STDs caused by bacteria
a. chlamydia (chlamydia trachomatis) - burning during urination, mucoid discharge
b. gonorrhea (neisseria gonorrhoeae) - pain upon urination, greenish yellow urethral discharge, can spread to eyes, mouth throat
c. syphilis (treponema pallidum) - chancre, rash, affects cardiovascular sys
3. Two other infections
a. bacterial vaginosis (gardnerella vainalis)
b. trichomonas vainalis, candida albicans

Definitions for Chapter 16 can be found here.

II. Development and Aging
A. Fertilization
1. Steps of fertilization
a. egg plasma membrane - zona pellucida (extracellular matrix), corona radiata (follicular cells)
b. sperm penetrate zona pellucida, 1 enters cell after acrosome forges pathway through zp, sperm and egg membranes fuse
c. upon sperm touching egg, egg's plasma membrane depolarizes
d. only sperm nucleus fuses to egg
Figure 17.1 from the text illustrates the steps of fertilization.
B. Pre-Embryonic and Embryonic Development
1. Processes of development
a. cleavage - mitotic cell division, no increase in size, each cell rcvs full complement of chromosomes and genes
b. growth - cell division accompanied by increase in size of daughter cells
c. morphogenesis - shaping of embryo, certain cells migrate in relation to other cells
d. differentiation - cells take on specific structure and function, 1st sys to become visibly differentiated is nervous sys
2. Extraembryonic membranes named for function in shelled animals
a. chorion - develops into fetal half of placenta - provides nourishment, oxygen, removes waste, blood vessels w/in chorionic villi - continuous w/umbilical blood vessels
b. allantois - collects urine, later becomes bladder, its blood vessels become umbilical blood vessels (umbilical arteries - O2 poor, umbilical veins - O2 rich)
c. yolk sac - first embryonic membrane to appear, contains many blood vessels, first site of blood cell formation
d. amnion - enlarges w/embryo/fetus, fluid cushion
Figure 17.2 from the text illustrates the extraembryonic membranes.
3. Stages of development
a. pre-embryonic development - first week, zygote->morula->blastocyst
Figure 17.3 from the text illustrates pre-embryonic development.b. embryonic development - 2nd wk
i. implantation chorion secretes enzymes and HCG
ii. HCG serves to maintain corpus luteum-> secretes progesterone so endometrium maintained (no menstruation)
iii. inner cell mass via gastrulation-> embryonic disk, yolk sac, & amniotic cavity
iv. primary germ layers formed from embryonic disk
c. embryonic development - 3rd wk
i. nervous sys - first to be visible
ii. heart development begins
d. embryonic development - 4th & 5th wk
i. body stalk connects embryo to chorion
ii. allantois in body stalk
iii. head and tail lift, body stalk moves anteriorly => umbilical cord
iv. limb buds appea
v. head enlarges, sense organs become more prominent, eyes, ears, nose apparent
Figure 17.6 from the text shows and illustrates a human embryo at the beginning of the fifth week.
e. embryonic development - 6th thru 8th weeks
i. embryo changes to form that resembles human being
ii. neck region develops, head in normal relationship with body
iii. nervous sys development allow reflex actions
Figure 17.4 from the text illustrates the stages of embryonic development.
Figure 17.5 from the text illustrates the course of development for the 3 primary germ layers.
C. Fetal Development
1. functions of progesterone & estrogen during pregnancy (source is placenta)
a. neg feedback on hypothalamus & anterior pituitary - prevent new follicles from maturing
b. maintain endometrium - no menstruation
2. Path of fetal bloodexchange of nutrients, oxygen, wastes is across chorionic villi
Figure 17.7 from the text shows the path of fetal cirulation.
3. Events of fetal development
a. 3rd and 4th months
i. head growth slows
ii. hair develops
iii. cartilage gets replaced by bone
iv. distinguish male from female
v. heartbeat heard with stethoscope
b. 5th through 7th months
i. movement felt by mom
ii. fetal position
iii. eyelids open
iv. lanugo & vernix caseosa
c. 8th through 9th months
i. weight gain 1 lb per week
ii. fetus rotates, head pointed down
4. Development of male and femal genitals differentiation depends on hormones present
a. normal development of the genitals
i. internal genitals - gonads develop during 7th wk
ii. prior to 7th wk, males & females both have Mullerian & Wolffian ducts
iii. external genitals
iv. small bud, urogenital groove
b. abnormal development of the genitals
i. presence or absence of SRY gene can cause XY female or XX male syndrome
ii. SRY gene causes testes to form, testes secrete: testosterone, anti-Mullerian hormone, dihydrotestosterone
iii. ambiguous sex determination - androgen insensitivity syndrome (plasma membrane receptors for testosterone ineffective), male pseudohermaphroditism
Figure 17.9 from the text illustrates the development of the internal and external genitals in males and females.
D. Pregnancy and Birth
1. energy level fluctuates, increase in weight
2. progesterone - relaxes smooth muscle-uterus & arterial walls, low blood pressure: renin-angiotensin-aldosterone mechanism by estrogen

a. aldosterone - sodium, water intake, blood volume increases 40%
b. increase in red blood cells, cardiac output increases 20-30%
3. Pulmonary values increase
a. increase in uterus size pushes internal organs superiorly, widens thoracic cavity
b. carbon dioxide levels fall - concentration gradient favorable to flow of CO2 from fetal blood
4. Other effects
a. enlargement of uterus compresses bladder and ureters
b. compression of inferior vena cava - decreases venous return=> edema varicose veins
c. placent produces peptide hormones - one makes cells resistant to insulin
d. striae gravidarum, darkening of skin
5. Birth
a. positive feedback - cervix stretches - causes uterine contractions & release of oxytocin from posterior pituitary gland
b. oxytocin stimulates uterine muscles
c. uterine contractions push fetus down, cervix stretches more cycle continues
6. Stage 1
a. effacement - cervical canal slowly disappears, babies head acts as wedge to assist cervical dilation
7. Stage 2
a. contractions - 1 minute each, 1-2 minutes apart
b. back of head faces up
c. episiotomy
d. umbilical cord cut & tied
8. Stage 3
a. afterbirth expelled
Figure 17.11 from the text shows the birthing process.
E. Development after Birth
1. Hypotheses of aging
a. genetic in origin - mitochondrial hypothesis of aging
b. whole-body process - changes to hormonal system, immune system, changes to tissue
c. extrinsic factors - diet, exercise, habits
2. Effect of age on body systems
a. skin - becomes thinner & less elastic; less adipose tissue in subcutaneous layer; sagging, wrinkling caused by loss of thickness. fewer sweat glands - skin cracks, fewer hair follicles
b. processing and transporting
i. heart shrinks, reduced cardiac output
ii. arteries harden, blood pressure rises over time
iii. blood flow to liver reduced, drugs not metabolized as efficeiently - lower doses required
iv. blood supply to kidneys reduced
v. loss of teeth
c. integration and coordination
i. loss in short-term memory, but can learn and remember new material
ii. neuron death may be due to reduced blood flow
iii. reaction time slows, more stimulation needed for senses
iv. hearing impacted
v. loss of skeletal muscle, reduction of bone density
d. the reproductive system
i. menopause, andropause

Definitions for Chapter 17 can be found here.

REFERENCES:
Mader, Syliva S. Human Biology. New York, NY: McGraw-Hill (2008).

Links provided throughout the summary take you to online sources.


IMPORTANT NOTE: Any time "text" or "the text" is referenced in the above summary, I am referring to the textbook Human Biology by Sylvia Mader (cited directly above).

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