Ovarian Function

Question 1

What are the two phases of the mestrual cycle?

Which hormone is present in each?

Answer 1

Follicular/Proliferative phase: oestrogen

Luteal/Secretory phase: progesterone and oestrogen

Question 2

Which secondary sex characteristics are controlled by which hormones in females?

Answer 2

Oestrogen: breats development, distribution of body fat

Adrenal androgens: growth of pubic and axillary hair, sex drive

Question 3

Describe the structure of the ovary?

Answer 3

Surface epithelium > theca > basal lamina > granulosa cells > antral fluid

Question 4

Describe the structure of the uterus?

Answer 4

Endometrium > myometrium > outer connective tissue > uterine artery

Question 5

Which parts of the ovary produce hormones?

Answer 5

Theca and granulosa cells

Question 6

Describe the timing of the phases of the menstrual cycle?

What is happening to the follicle in each stage?

Answer 6

Follicular/Proliferative: days 0-13 (variable)
Follicle growth in ovary

Ovulation at day 14 (variable)
Release of oocyte

Luteal/Secretory phase: days 15-28 (constant)
Ruptured follicle transforms into corpus luteum

Question 7

Describe the changes that occur in the endometrial lining during the menstrual cycle?

Answer 7

Menses: endometrium shed with no pregnancy

Proliferative phase: new layer of endometrium in preparation for pregnancy

Secretory phase: conversion of endometrium into a secretory structure to promote implantation

Question 8

Describe the menstrual and uterine cycles?

Answer 8

Question 9

What is the corpus albicans?

Answer 9

Regressed form of corpus luteum that appoears when pregnancy does not occur

Question 10

Describe the hormonal control in the follicular phase of the menstrual cycle?

Answer 10

FSH > stimulates follicular development
> granulosa cells produce oestrogen (positive feedback)

LH > stimulates thecal cells to produce androgens > converted to oestrogen in granulosa cells (under control of FSH)

Question 11

Describe the hormonal control of menstruation during ovulation?

Answer 11

High oestrogen > switch to positive feedback to GnRH > LH and FSH surge

High inhibin > inhibits FSH

Low progesterone > positive feedback on GnRH and LH

Question 12

Why does inhibin inhibit FSH during ovulation?

Answer 12

Getting ready for conception > don’t need a new follicle

Question 13

Describe why oestrogen levels drop after ovulation?

Answer 13

No more follicle to produce it

Question 14

Describe the cervical mucous that is present during ovulation?

Answer 14

Abundant, clear, non-viscous

Question 15

Describe the hormonal control of the menstrual cycle during the early luteal phase?

Answer 15

Corpus luteum formed from granulosa cells, secretes:
High oestrogen
High progesterone
High inihibin

Decreased GnRH, LH and FSH

Question 16

Why are progesterone, oestrogen and inhibin high during the early luteal phase?

Answer 16

Oestrogen and progesterone: maintain endometrium

Inhibin: prevent new follicle formation

Question 17

Describe the cervical mucous produced during the early luteal phase?

Answer 17

Thick, sticky, viscous mucous

Protect intrauterine environment (don’t need any more sperm)

Question 18

Describe the change in body temperature that occurs in the mestrual cycle?

Answer 18

Rises by 0.5 degrees during the early luteal phase

Question 19

Describe the hormonal control of the menstrual cycle during the late luteal phase?

Answer 19

Pregnancy: maintain high hormones

No pregnancy: CL dies > low oestrogen and progesterone, low inhibin > increased FSH
Increased LH

Question 20

Describe the process of fertilisation?

Answer 20

Sperm capacitation occurs in vagina > sperm reach oocyte in Fallopian tube > acrosomal reaction, zona pellucida and cell junctions dissolve > membranes fuse and sperm nucleus enters > cotrical reaction > diploid cell = zygote

Question 21

What is the purpose of the cortical reaction?

Answer 21

Prevents more than one sperm from entering

Question 22

What are the lifespans on sperm and secondary oocytes?

Answer 22

Sperm: 48 hours

Secondary oocyte: 12-24 hours

Question 23

Describe the process of zygote development, from ovulation to implantation?

Answer 23

Ovulation >

Day 1: fertilisation
Days 2-4: cell division
Days 4-5: blastocyst reaches uterus
Days 5-9: blastocyst implants

Question 24

Describe how the endometrium changes after implantation?

Answer 24

Trophoblastoic cells of blastocyst invade endometrium > blastocyst becomes completely buried > endometrium becomes decidus

Question 25

Describe the three phases of pregnancy?

Answer 25

Early pregnancy: weeks 1-2

Embryonic period: weeks 3-8

Foetal period: weeks 9-term

Question 26

Describe the susceptibility during early pregnancy?

Answer 26

Not susceptible to teratogens

Susceptible to chromosomal abnormalities

Environmental disturbances may interfere with implantation

Question 27

Describe the susceptibility during the embryonic period?

Answer 27

Most susceptible to teratogens

Question 28

When are all organ systems present?

Answer 28

Embryonic period

Question 29

Describe the susceptibilityduring the foetal period?

Answer 29

Physiological defects

Minor morphological abnromalities

Functional disturbances

Question 30

Describe the factors that influence normal foetal gorwth?

Answer 30

Genetic factors

Environmental factors:

• multiple pregnancies
• maternal malnutrition
• placental function
• smoking
• alcohol
• drugs
• infectious agents
• exercise
• environmental chemicals

Question 31

Describe the efficacy of various contraceptive methods?

Answer 31