Sex steroid physiology Flashcards
What is a polar body?
Produced in oogenesis. Doesn’t have the ability to be fertilised
What does the presence of two polar bodies mean?
Sperm entry and completed 2nd meiotic division
What are the two stages of the ovarian cycle?
Follicular stage
Luteal stage
What is a primary follicle?
Primary oocyte surrounded by a single layer of granulosa cells
What process ends the follicular phase?
Ovulation
What is the corpus luteum?
Follicular cells which are lutenised
What hormone does the corpus luteum secrete?
Progesterone
What does the progesterone do?
Prepares the uterus lining for implantation
How long does the corpus luteum grow for?
8-9
What happens to the corpus luteum if pregnancy does not occur?
It degenerates
What hormone does the hypothalamus secrete which acts on the anterior pituitary?
Gonadotropin releasing hormone GnRH
Which two hormones does the anterior pituitary secrete?
FSH
LH
What does FSH do?
Acts on the ovary and stimulates the development of follicles
What does LH do?
Acts on ovary and stimulates follicle maturation, ovulation and development of the corpus luteum
What are theca cells?
Cells which make up the follicle
What do theca cells do?
Produce androgen which are converted to oestrogens
What does oestradiol do?
Thickens the endometrium and thins cervical mucus
What suppresses FSH production?
Oestrogen
What do the granulosa have?
LH receptors
What happens to hormone levels during ovulation?
LH and FSH levels fall
How is ovulation detected?
? High levels of LH
What happens if no hCG is produced?
Corpus luteum degenerates and forms the corpus albicans
What is the corpus albicans?
Connective tissue of type I collagen which forms form the corpus luteum
Which enzyme converts androgens from theca cells to oestrogens?
Aromatase enzyme
Where does the converting enzyme come from?
Granulosa cells
What stimulates the theca cells to produce androgens?
LH
What does FSH do?
Stimulates granulosa cells to convert androgens
In which phase of the cycle is LH high?
Follicular phase
What will inhibit FSH?
High oestrogen levels due to negative feedback
What happens when oestrogen peaks?
LH rises
What happens when LH rises?
Ovulation occurs
What happens during ovulation?
Oocyte is released from the ovary into the fallopian tube
What do the granulosa and theca cells develop into?
Corpus luteum
If progesterone levels are too high what will happen?
FSH/ LH is inhibited
