Ch. 20 Day 2

Question 1

Procreation

Answer 1

Sexual response varies between genders and individuals

Question 2

Procreation: excitation

Answer 2

increased muscle tone, vasocongestion of sexual organs; aka arousal

Question 3

Procreation: plateau

Answer 3

continued vasocongestion

Question 4

Procreation: orgasm

Answer 4

contraction of uterus/vagina and male ejaculatory organs

Question 5

Procreation: resolution

Answer 5

body returns to pre-excitation condition

• -men experience refractory period: not able to ejaculate
• -females don’t really have refractory period

Question 6

T/F: Stimulation or inhibition of erection can occur with or without input from higher brain centers.

Answer 6

True

-whole process of stimulation starts w/ nitric oxide

Question 7

Parasympathetic stimulates or inhibits?

Answer 7

Stimulates

Question 8

Sympathetic stimulates or inhibits?

Answer 8

Inhibits

Question 9

Mechanism of penile vasodilatory response and basis for action of Sildenafil, similar vasoactive drugs work by inhibiting ____.

Answer 9

Phosphodiesterase (PDE-5)

PDE-5 activates Ca2+ channels, stimulates smooth muscle contraction –> vasoconstriction –> no erection

PDE-5 blocks Ca2+ entry, promotes smooth muscle relaxation –> vasodilation –> erection

Question 10

Are there any comparable drugs currently marketed for female sexual dysfunction?

Answer 10

No

Question 11

Male contraception

Answer 11

Vasectomy

• a) most widely used and reliable form of male contraception
• b) vas deferens cut and tied to prohibit sperm transport
• c) does NOT affect testosterone production or ejaculation

Newer methods of contraception:

• a) suppressing gonadotropin secretion
• b) gossypol - interferes w/ sperm production

Question 12

Female contraception

Answer 12

Contraceptive pill

• a) includes synthetic estradiol and progesterone
• b) acts like prolonged luteal phase
• c) promotes negative feedback inhibition of GnRH –> no ovulation
• d) endometrium still proliferates
• e) placebo pills taken for 1 week to allow menstruation
• f) newer pills have reduced risk for endometrial and ovarian cancers and reduction of osteoporosis

Question 13

The most effective types of female contraceptives are those that?

Answer 13

Require the least effort by the user

–ex: implant, vasectomy, female sterilization

Question 14

After ovulation, how long are the egg & sperm viable?

Answer 14

Egg is viable for about 1-2 days

Sperm survive 5-6 days in female reproductive tract

Question 15

After fertilization, describe: Day 1, Days 2-4, Days 4-5, Days 5-9

Answer 15

Day 1: fertilization

Days 2-4: cell division

Days 4-5: blastocyst reaches uterus

Days 5-9: blastocyst implants in uterine wall

Question 16

In order to become mfertilization-conpetant, sperm must undergo ____ in the female reproductive tract.

Answer 16

Capacitation

–enzymes on head of sperm are removed, sperm is now ready to fertilize egg

Question 17

Sperm and fertilization

Answer 17

Over 300 million sperm enter female at ejaculation

• only about 100 of these live to enter fallopian tube
• in order to fertilize ovum, sperm must become capacitated; takes at least 7 hours after ejaculation
• -> pH increases
• -> hyperactivation of flagellum
• capacitated sperm guided to oocyte by chemotaxis and thermotaxis

Question 18

Fertilization occurs in?

Answer 18

Distal part of fallopian tube

sperm penetrates outer layers via enzymatically-mediated acrosomal reaction

Question 19

Cortical reaction

Answer 19

when sperm enters oocyte, Ca2+ is released from endoplasmic reticulum

• calcium wave travels through oocyte to opposite side from entry of sperm
• Ca2+ has several effects:
• -> prevents other sperm from entering oocyte (polyspermy)
• -> activates oocyte to finish meiosis to become haploid ovum

Question 20

Fertilization

Answer 20

12 hours after sperm enter oocyte, nuclear envelope around ovum disappears, and chromosomes join to form a diploid zygote

• -a) monozygotic (identical) twins - single ovum splits
• -b) dizygotic (fraternal) twins - 2 eggs fertilized by sperm

Sperm contributes 1/2 chromosomes, centrosome

Egg contributes 1/2 chromosomes, cytoplasm, all other organelles

Question 21

Are mitochondria maternally or paternally inherited?

Answer 21

Maternally

Question 22

Why are mitochondria maternally inherited?

Answer 22

Autophagy is cellular process whereby worn-out/damaged proteins and organelles are degraded and their components recycled

There’s a type of autophagy that is mitochondrial-specific: mitophagy

Mitophagy of sperm-derived mitochondria upon fertilization
–unknown why sperm-derived mitochondria are selectively targeted

Question 23

Zygote

Answer 23

begins dividing in fallopian tube, implants in uterus as a blastocyst (~100 cells) 710 days post-fertilization

High levels of progesterone limit muscular contractions, so movement through fallopian tube to uterus is slow

Question 24

Blastocyst

Answer 24

hollow ball of cells formed as division of zygote continues

Layers:

• 1) inner cell mass –> fetus
• 2) trophoblast –> chorion –> placenta

Question 25

Cleavage

Answer 25

rapid mitosis, which form small of cells (Morula) - enters uterus about 3 days post-fertilization begins 30-36 hours after fertilization

Question 26

6 days post-fertilization

Answer 26

trophoblast cells secrete enzyme that allows blastocyst to "eat" into endometrium

Question 27

7-10 days post-fertilization

Answer 27

blastocyst completely implanted

Question 28

Implantation

Answer 28

Between days 7-12, chorion splits into: - 1) cytotrophoblast (inner) - 2) syncytiotrophoblast (outer) Developing cytotrophoblast and inner cell mass separated by amniotic cavity Syncytiotrophoblast secretes protein-digesting enzymes and creates blood-filled cavities in endometrium Cytotrophoblast sends villi into these pools of maternal blood, forming chorion frondosum Placental structures are "immunologically privileged site" - barrier preventing direct contact between maternal blood and fetal antigens

Question 29

Fetal part of blastocyst becomes?

Answer 29

1. Endoderm --> gut organs | 2. Ectoderm --> skin and nervous system

Question 30

Mesoderm

Answer 30

develops later --> muscle, bones and CT

Question 31

Chorion

Answer 31

portion of trophoblast layer which becomes embryonic portion of placenta

Question 32

ICM --> ?

Answer 32

embryo and extra embryonic membrane, including amnion, yolk sac

Question 33

Placenta and amniotic sac formation

Answer 33

As blastocyst develops, endometrium also changes to form decide basalis -1) joins w/ chorion frondosum to form placenta part of chorion envelops the growing embryo - 1) fluid-filled space between becomes amniotic sac - 2) amniotic fluid becomes from isotonic secretion, urine from fetus, and sloughed cells

Question 34

Circulation of blood in placenta

Answer 34

Umbilical arteries deliver fetal blood to placental vessels Blood circulates w/in placenta and returns to fetus via umbilical vein Maternal blood is also delivered to/from placenta Thus, maternal and fetal blood do NOT mix; are separated by only 2 cell layers Molecules (oxygen and nutrients) diffuse across tissues of placenta for exchange, from maternal blood to fetal blood Carbon dioxide and wastes diffuse from fetal blood to maternal blood Placenta degrades maternal molecules that may harm fetus

Question 35

Human chorionic gonadotropin (hCG)

Answer 35

Secreted from chorionic villi and placenta Binds to LH receptors on corpus luteum Maintains viability of C.L., which continues to produce progesterone By roughly 2-3 months, placenta takes over production of hormones Progesterone: supports endometrium, inhibits uterine contractions Estrogen: supports endometrium, development of milk glands

Question 36

From the 2nd trimester-parturition, ____ takes over production of progesterone, estrogen.

Answer 36

Placenta

Question 37

What is used in pregnancy tests to determine if pregnancy has occurred?

Answer 37

hCG

Question 38

Human placental lactogen (hPL)

Answer 38

Secreted by placenta in proportion to placental development Main function: induce metabolic shift in favor of fetus decreased maternal sensitivity --> increased maternal blood glucose decreased maternal glucose utilization --> spares glucose for fetus increased lipolysis --> increased free fatty acids for use by mother; glucose and ketone bodies used by fetus *Supports fetal nutrition even under conditions of maternal malnutrition

Question 39

Labor and Delivery

Answer 39

roughly 40 weeks precise initial trigger not clear, but probably due to combination of various factors: - 1) secretion of CRH by placenta --> uterine production of prostaglandins --> uterine contractions - 2) stretch of cervix induced by baby's head --> central reflex --> oxytocin secretion --> uterine contractions - 3) decrease of progesterone secretion by placenta --> removes inhibition of uterine contractions

Question 40

Mammary gland structure and lactation

Answer 40

composed of 15-20 lobes separated by adipose tissue each lobe made up of lobules composed of glandular alveoli that secrete milk in lactation milk flows from secondary tubules --> mammary ducts --> lactiferous duct --> nipple during pregnancy, cortisol, thyroxine, and insulin make mammary glands more sensitive to rising progesterone and estradiol levels - -progesterone stimulates alveoli growth - -estradiol stimulates tubule and duct growth

Question 41

Control of lactation

Answer 41

prolactin from pituitary gland stimulates production of milk proteins, casein and lactalbumin prolactin is inhibited by PIH (dopamine) from pituitary gland. PIH stimulated by estradiol secretion --when placenta is shed at birth, estradiol levels drop, lifting inhibition or prolactin

Question 42

Breast feeding and immunity

Answer 42

IgG antibodies passed from mother to child in utero IgA antibodies passed to child from breast milk - 1) these provide passive immunity for the first several months of life until baby can develop its own antibodies - 2) also promotes development of baby's own active immmunity

Question 43

Menopause

Answer 43

female (usually > 50 years) cessation of reproduction-competent phase of life - ovulation, menstrual cycles gradually becomes erratic and ultimately cease appears to be due to development of insensitivity to FSH, LH in ovaries --> decreased production of estrogen, progesterone

Question 44

Symptoms of menopause are due to loss of ____.

Answer 44

Estradiol

Question 45

Symptoms of menopause

Answer 45

a) hot flashes are produced by vasomotor disturbances b) walls of urethra and vagina atrophy, and vaginal glands no longer produce lubrication c) after menopause, risk for atherosclerosis and osteoporosis increases - -> estradiol is needed for bone deposition, so menopausal women are at increased risk for osteoporosis - -> adipose tissue does make a weak form of estradiol called estrone. Thus, heavier women have reduced risk of osteoporosis

Question 46

Andropause

Answer 46

male Testosterone production decreases with aging, but precise role of decreased testosterone is not clear, since physical and psychological symptoms of aging in men and have not been clearly linked to a decline in testosterone