chapter 27 part 3

Question 1

ovarian follicle

Answer 1

individual developing oocyte surrounded by cells to form ovarian follicle

Question 2

function of ovarian follicle

Answer 2

nurture oocytes during development and releases hormones

Question 3

stages of development of follicles

Answer 3

primordial follicle
primary follicle
secondary follicle
graafian (mature vesicular) follicle

Question 4

primordial follicle

Answer 4

• First class of follicle formed
• single layer of cells surrounding primary oocyte

Question 5

primary follicle

Answer 5

• contains single layer of granulosa cells surrounding the primary oocyte
• Function: granulosa cells produce estrogen and progesterone

Question 6

secondary follicle

Answer 6

contains multiple layers of granulosa cells and thecal cells surrounding primary oocyte
oocyte secretes substances to form a transparent extracellular layer : zona pellucida

Question 7

zona pellucida

Answer 7

shell that surrounds primary oocyte inside of follicle

Question 8

graafian (mature vesicular) follicle

Answer 8

only seen after puberty
contains a secondary oocyte

Question 9

ovarian cycle

Answer 9

monthly series of events that leads to maturation of an ovum

Question 10

before puberty

Answer 10

release of small amounts of estrogen prevents GnRH release

Question 11

What makes hypothalamus insensitive to estrogen

Answer 11

increasing leptin
ages 8-9 : release GnRH, FSH and LH
release estrogen in ovaries

Question 12

FSH and LH release begins

Answer 12

hormone levels continue to rise for several years

Question 13

once adult cycle is reached

Answer 13

menarche occurs
first menstrual period: 11-13 years

Question 14

regulation of ovarian cycle by

Answer 14

HPG axis
ovarian cycle is completed once per month

Question 15

ovarian cycle steps

Answer 15

1. The hypothalamus releases GnRH
2. The anterior pituitary releases FSH and LH
3. FSH and LH influence follicles
   - FSH causes granulosa cells and thecal cells of follicles to grow and release estrogens
   - LH stimulates release of estradiol: primary hormone released by ovaries and is converted to estrogen
4. rising estrogen levels in blood plasma inhibits GnRH release
   - FSH relese drops rapidly
5. dominant follicle continues development to a Graafian follicle
6. LH surge triggers ovulation and formation of corpus luteum
7. rising progesterone and estrogen levels from corpus luteum inhibits GnRH release

Question 16

importance of FSH levels dropping

Answer 16

only the dominant follicle survives this drop in FSH: continues development
dominant follicle is the most mature follicle between the 2 ovaries

Question 17

corpus luteum

Answer 17

• yellow body
• formed from granulosa and thecal cells
• releases large amounts of - progesterone and estrogen
  makes sure oocyte survives

Question 18

progesterone

Answer 18

maintains uterine lining and affects hormone release from CNS

Question 19

in step 7

Answer 19

• FSH and LH drop: follicle development stops
• prevents multiple ovulation events

Question 20

phases of the ovarian cycle

Answer 20

1. follicular phase
2. ovulation
3. luteal phase

Question 21

follicular phase

Answer 21

• many large follicles grow in ovaries
• dominant follicle survives drop in FSH and releases large amount of estrogen : blood levels of estrogen rise
• the end of this phase is marked by completion of meiosis 1 to form secondary oocyte and first polar body

Question 22

ovulation

Answer 22

• rupture of ovary wall and release of secondary oocyte
• usually one secondary oocyte is ovulated
• sometimes oocytes can be released independently of hormonal cycle

Question 23

luteul phase

Answer 23

• occurs after ovulation
• always 14 days
• ruptured follicle collapses and remaining granulosa cells form corpus luteum

Question 24

corpus luteum may or may not persist

Answer 24

if fertilization does not occur: corpus luteum degenerates
release of progesterone ends: uterine lining no longer maintained
if fertilization does occur: corpus luteum remains and continues to release hormones
prevents spontaneous abortion
persist until placenta formation, then degenerates

Question 25

the uterine cycle

Answer 25

- also called the menstrual cycle - endometrium is highly responsive to estrogens

Question 26

phases of uterine cycle

Answer 26

1. menstrual phase 2. proliferative phase 3. secretory phase

Question 27

menstrual phase

Answer 27

- days 0-4 - occurs in early follicular phase - stratum functionalis detaches in the absence of progesterone: most of endometrial lining is shed

Question 28

proliferative phase

Answer 28

- days 5-14 - occurs during follicular phase - Estrogen release stimulates formation of new stratum functionalis - ends when ovulation occurs

Question 29

secretory phase

Answer 29

- days 15-28 - always 14 days - occurs during luteul phase - progesterone levels rise early in phase - endometrial layer thickens and endometrial glands supply lining w nutrients for embryo - cervical plug thiclens to prevent entry of extra sperm, bacteria or pathogens - if fertilization does not occur: corpus luteum degenerates and progesterone levels drop at the end of phase - functional layer will begin to shed: back to day 0

Question 30

rising estrogen levels

Answer 30

1. promotes oogenesis and follicle growth 2. promotes growth and maturation of female reproductive structures 3. causes sudden growth spurt and eventually cessation of bone growth 4. Appearance of secondary sex characteristics: breast development, increased body fat (hips/thighs: extra energy reserve during pregnancy), wider and lighter pelvis (easier for infant to release during birth)

Question 31

rising progesterone levels

Answer 31

1. Work in tandem w estrogen to establish/maintain the ovarian cycle 2. promotes changes in cervical mucus 3. maintains pregnancy