Ovarian Function Flashcards
What are the two phases of the mestrual cycle?
Which hormone is present in each?
Follicular/Proliferative phase: oestrogen
Luteal/Secretory phase: progesterone and oestrogen
Which secondary sex characteristics are controlled by which hormones in females?
Oestrogen: breats development, distribution of body fat
Adrenal androgens: growth of pubic and axillary hair, sex drive
Describe the structure of the ovary?
Surface epithelium > theca > basal lamina > granulosa cells > antral fluid
Describe the structure of the uterus?
Endometrium > myometrium > outer connective tissue > uterine artery
Which parts of the ovary produce hormones?
Theca and granulosa cells
Describe the timing of the phases of the menstrual cycle?
What is happening to the follicle in each stage?
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
Describe the changes that occur in the endometrial lining during the menstrual cycle?
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
Describe the menstrual and uterine cycles?
What is the corpus albicans?
Regressed form of corpus luteum that appoears when pregnancy does not occur
Describe the hormonal control in the follicular phase of the menstrual cycle?
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)
Describe the hormonal control of menstruation during ovulation?
High oestrogen > switch to positive feedback to GnRH > LH and FSH surge
High inhibin > inhibits FSH
Low progesterone > positive feedback on GnRH and LH
Why does inhibin inhibit FSH during ovulation?
Getting ready for conception > don’t need a new follicle
Describe why oestrogen levels drop after ovulation?
No more follicle to produce it
Describe the cervical mucous that is present during ovulation?
Abundant, clear, non-viscous
Describe the hormonal control of the menstrual cycle during the early luteal phase?
Corpus luteum formed from granulosa cells, secretes:
High oestrogen
High progesterone
High inihibin
Decreased GnRH, LH and FSH
Why are progesterone, oestrogen and inhibin high during the early luteal phase?
Oestrogen and progesterone: maintain endometrium
Inhibin: prevent new follicle formation
Describe the cervical mucous produced during the early luteal phase?
Thick, sticky, viscous mucous
Protect intrauterine environment (don’t need any more sperm)
Describe the change in body temperature that occurs in the mestrual cycle?
Rises by 0.5 degrees during the early luteal phase
Describe the hormonal control of the menstrual cycle during the late luteal phase?
Pregnancy: maintain high hormones
No pregnancy: CL dies > low oestrogen and progesterone, low inhibin > increased FSH
Increased LH
Describe the process of fertilisation?
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
What is the purpose of the cortical reaction?
Prevents more than one sperm from entering
What are the lifespans on sperm and secondary oocytes?
Sperm: 48 hours
Secondary oocyte: 12-24 hours
Describe the process of zygote development, from ovulation to implantation?
Ovulation >
Day 1: fertilisation
Days 2-4: cell division
Days 4-5: blastocyst reaches uterus
Days 5-9: blastocyst implants
Describe how the endometrium changes after implantation?
Trophoblastoic cells of blastocyst invade endometrium > blastocyst becomes completely buried > endometrium becomes decidus
