Menstrual Cycle Flashcards
What are the basics of the menstrual cycle?
Preparation
- of gamete
- of endometrium
Ovulation
Waiting
What controls the menstrual cycle?
Gonadotrophins - act on the ovary
Ovarian steroids - act on tissues of reproductive tract
What are the main gonadotrophins?
LH
FSH
What are the effects of FSH?
Stimulates early development of the follicles
Binds to granulosa cells - supports oocytes
What are the effects of LH?
Responsible for LH surge
Maintains corpus luteum
What are the 2 main cycles of the menstrual cycles?
Ovarian cycle
Uterine cycle
What are the 2 stages of the ovarian cycle?
Follicular phase
Luteal phase
When does the follicular phase take place?
Before ovulation
What hormone controls the follicular phase?
FSH
What happens in the follicular phase?
FSH increases Early development of follicles Follicle produces oestrogen Oestrogen increases - causes positive feedback Inhibin increases When LH rises more than FSH = ovulation
What is the role of inhibin?
Prevent more than one follicle developing
What happens to the oocyte during ovulation?
Meiosis 1 completes
Meiosis 2 starts
Mature oocyte extruded through capsule of the ovary
When does the luteal phase occur?
After ovulation
How long does the luteal phase take?
14 days
What happens in the luteal phase?
Follicle luteinised
Follicle secretes large amounts of oestrogen and progesterone
Follicle produces inhibin
What happens if the oocyte is not fertilised?
Oestrogen, progesterone + inhibin levels drop
What is the uterine cycle?
Response of the uterus + endometrium in response to hormones
What are the stages of the uterine cycle?
Proliferative stage
Secretory stage
Menstrual stage
What is the histology of the uterus in the early proliferative stage?
Glands are sparse + straight
What is the histology of the uterus in the late proliferative stage?
Functional layer doubled
Glands coiled
What is the histology of the uterus in the early secretory stage?
Endometrium maximum thickness
Very pronounced coiled glands
What is the histology of the uterus in the late secretory stage?
Glands have saw tooth appearance
What happens in the proliferative stage?
Endometrium proliferates in response to oestrogen
What happens in the secretory stage?
Glands become secretory - due to progesterone
Endometrium prepares to shed lining
What happens in the menstrual stage?
Endometrial lining is shed
What is the normal duration for a menstrual cycle?
21-35 days
What factors can affect the menstrual cycle?
Pregnancy Lactation Hormonal contraception Emotional stress Low body weight
