S2 EXAM- REPRODUCTION SYSTEM Flashcards
What does the follicle stimulating hormone do?
- From pituitary gland, targets the ovaries
- Stimulates the development and maturation of ovarian follicles
- Increases oestrogen
Luteinising hormone?
- from pituitary gland, targets ovaries
- promotes final maturation of ovarian follicle
- formation of corpus luteum, which secretes prog amd oest
Oestrogen?
From ovarian follicle, targets brain
Increases sexual maturation
Progesterone?
From corpus luteum, targets the brain
As prog increases, luteinising hormone decreases. Stops periods from coming
Human chorionic gonadotropin?
From placenta, targets the corpus luteum
Maintains the corpus luteum during the early stages of pregnancy
Oxytocin
From pituitary gland, targets the uterus and breasts
Causes uterine contractions amd promotes movement of milk In the breasts
Day 1-5 of cycle
Reduced oestrogen and progesterone causes the shedding of endometrium lining
Day 6-13
Follicles continue to divide and enlarge due to FSH. Secretes follicular fluid that protects and nourishes the oocyte. Forms mature follicle. FSH reduces.
The endometrium lining builds up, increasing blood vessels and mucous glands.
Day 14
Ovulation.
Mature follicle bursts, secondary oo the releases.
Most fertile phase- increased oestrogen causes increased FSH and massive spike in luteinising hormone
Day 15-25
Corpus luteum causes progesterone and oestrogen to increase. Lasts 8-10 days. If fertilisation, HcG produced by embryo maintains the corpus luteum to continue producing prog. Endometrial lining is maintained , secretes watery mucous to sustain possible embryo.
Oogenesis
Before birth- millions of oogonia develop. Finite number. Primary oocyte begins prophase 1.
At birth- 1000 still remain
At puberty- luteinising hormone and follicle stimulating hormone are released from pituitary gland. FSH acts on follicle cells, producing and releasing oestrogen. Oestrogen starts meiosis 1, primary oocyte becomes secondary oocyte, starts meiosis 2 but stops at day 14.
Ovulation - if no fertilisation, secondary oocyte remains dormant. If fertilisation, meiosis 2 is completed to produce mature ovum.
Spermatogenesis
Spermatogia begins dividing at puberty by mitosis. Some become primary spermatocytes. These undergo meiosis 1 and become secondary spermatocytes. These undergo meiosis 2 and become spermatids. Spermatids mature in spermatozoa.
Reproductive hormones in men
FSH- stimulates testes to create sperm
LH- stimulates testes to secrete testosterone
Testosterone- development of immature sperm into mature spermatozoa.
Oxytocin- movement of sperm, production of testosterone.
Infertility methods
Gamete intra fallopian transfer (GIFT); sper and eggs collected in a lab and inserted into a woman
In vitro fertilisation (IVF); hormones to stimulate ovaries and prepare uterine lining. Eggs and sperm mixed, embryo interred into uterus.
Surrogacy; another woman carries baby and gives it to couple.
Fertilisation
Occurs at top third of Fallopian tube. Enzymes in sperm head breaks down the corona radiata to enter ova. Only the head enters, fertilisation barrier forms around ovum so no other sperm an enter. Secondary oocyte completes meiosis 2 to form mature ovum.
Pronuclei fuse to make a diploid zygote—> starts mitosis to multiply
