Reproduction: Uterine cycle, menstrual cycle, fertilization

Question 1

What are the 4 phases of the uterine cycle?

Answer 1

menstruation;
proliferative phase;
secretory phase;
premenstruation

Question 2

when does the uterine cycle begin?

Answer 2

day 1 of menses => degeneration of corpus luteum

Question 3

When does the proliferative phase begin?

Answer 3

after menses in latter portion of follicular phase of menstrual cycle and ending near ovulation

Question 4

What is the hormone responsible for the proliferative phase?

Answer 4

estrogen

Question 5

What does elevated estrogen provide in the proliferative phase?

Answer 5

proliferation of endometrial cells;
increase in length and number of endometrial glands;
increase blood flow to uterus

Question 6

What is the interaction of estrogen and progesterone in proliferative phase?

Answer 6

estrogen stimulates progesterone receptor increase on the endometrium for fertilization preparation

Question 7

What occurs in the uterus at the end of the proliferative phase and into the secretory phase?

Answer 7

edema in the uterus

Question 8

Secretory phase and what menstrual cycle phase are the same?

Answer 8

luteul phase

Question 9

What characterizes the secretory phase?

Answer 9

endometrial cell hypertrophy;
increased vascularity;
edema

Question 10

What is the principle hormone of the secretory phase?

Answer 10

progesterone

Question 11

What do elevated levels of progesterone lead to?

Answer 11

thick secretion of glycoproteins, sugars, amino acids;
increases cell proliferation;
increases vascularization;
depresses uterine contractility

Question 12

Describe the premenstrual phase of the uterine cycle

Answer 12

artery constriction => ischemia, anoxia;

superficial layer of endometrium degenerates => blood and tissue in uterine lumen

Question 13

what are 4 phases of menstrual cycle

Answer 13

menses;
follicular phase;
ovulation;
luteal phase

Question 14

When does the variation occur in the menstrual cycle?

Answer 14

follicular phase has variation;

luteal phase is always 14 days

Question 15

Menses marks day 1. What triggers this?

Answer 15

decrease in estrogen and progesterone

Question 16

What does a decrease in estrogen and progesterone cause?

Answer 16

loss of endometrium support=> tissue necrosis, arterial rupture => sloughing of superficial layer and bleeding

Question 17

What is the significance of the follicular phase’s decrease in progesterone and estrogen?

Answer 17

negative feedback is removed => increase in frequency of GnRH pulses => stimulates FSH secretion for follicular growth

Question 18

What leads to the dominant follicle?

Answer 18

one secretes more estradiol to become dominant => atresia occurs to others

Question 19

What leads to the FSH and LH secretion spike during the follicular phase leading to ovulation?

Answer 19

Estrogen rises until critical point where it is positive feedback on GnRH to pulsatile stimulation of LH and FSH

Question 20

What causes ovulation?

Answer 20

LH surge and high estrogen levels trigger ovulation

Question 21

What happens to the follicle during ovulation?

Answer 21

follicle ruptures 24-36 hours after LH surge => oocyte resumes meiosis and 1st polar body extruded

Question 22

What occurs to the follicle during the luteal phase?

Answer 22

forms corpus luteum => secretes high levels of progesterone and low estrogen

Question 23

What is the purpose of high progesterone during the luteal phase?

Answer 23

negative feedback to slow GnRH pulse => LH and FSH remain low

Question 24

What happens to the corpus luteum if no fertilization occurs?

Answer 24

luteolysis causing progesterone and estrogen to decrease until hormonal suppor for endometrium declines and cells undergo apoptosis

Question 25

What is the purpose of the semen associated with the sperm?

Answer 25

neutralize the acidic vaginal fluids to permit sperm survival

Question 26

In preparation for fertilization, what hormone is released and what is its action?

Answer 26

estrogen is increased to thin the cervical mucus for easier transit of sperm to uterus

Question 27

Define capacitation

Answer 27

uterine fluid solubilizes the glycoproteins coating the sperm

Question 28

Purpose for capacitation

Answer 28

aids in fertilization by increasing energy metabolism, enhancing motility, allowing acrosome rxn at zona pellucida

Question 29

What aids in sperm movement through the uterus?

Answer 29

contraction of the female reproductive tract => mostly the uterus

Question 30

Name the path the oocyte must take to reach the uterus. What enables this process?

Answer 30

fimbria => infundibulum => ampulla => isthmus => uterus;

via peristaltic contractions

Question 31

How long are sperm viable after ejaculation?

Answer 31

72 hours

Question 32

What happens after sperm reaches the oocyte?

Answer 32

binds to zona pellucida to under acrosome reaction

Question 33

Once the acrosome reaction takes place, what is the next step?

Answer 33

sperm and oocyte membranes fuse and sperm cell contents enter oocyte

Question 34

What disease will limit the membrane fusion? Why?

Answer 34

Kartagener’s syndrome => poor sperm motility

Question 35

Define cortical reaction

Answer 35

occurs when membranes fuse and zona pellucida hardens to prevent additional sperm from entering oocyte

Question 36

Before male and female pronuclei fuse, what occurs to the oocyte?

Answer 36

undergoes 2nd meiotic division producing 2nd polar body and female pronucleus

Question 37

What forms the embryo?

Answer 37

male pronucleus and female pronucleus

Question 38

Why does an embryo remain in the ampulla for several days?

Answer 38

allows progesterone levels to decline =>uterine and fallopian tube musculature relaxes => easier pass into uterus

Question 39

When does the embryo arrive in uterus and implant?

Answer 39

arrives 3 days after fertilization;

implants in uterus 3 days after arriving

Question 40

Before implanting in the uterus, what must the embryo do?

Answer 40

develop a vasculature to aid in nutrient receiving