Feedback mechanisms are used in living organisms both to promote and respond to change.
Describe the hormone feedback mechanisms that help to prepare a woman's body for pregnancy, sustain the pregnancy and then give birth.
Preparing the woman's body for pregnancy:
FSH stimulates estrogen secretion by the developing follicle.
Estrogen increases FSH receptors, boosting estrogen production/causing positive feedback.
Estrogen stimulates repair/thickening of the endometrium/uterus lining.
High levels of estrogen stimulate LH production/inhibit FSH secretion (negative feedback).
LH surge/peak stimulates ovulation.
Sustaining pregnancy:
LH stimulates development of the corpus luteum / corpus luteum secretes progesterone.
Progesterone inhibits FSH/LH secretion (negative feedback).
Progesterone maintains the lining of the uterus/endometrium for pregnancy/implantation of the embryo.
Progesterone inhibits uterine contractions.
HCG secreted by the embryo stimulates maintenance of the corpus luteum.
Childbirth:
Oxytocin stimulates uterine/myometrial contractions which stimulate oxytocin secretion.
Positive feedback mechanism is used to stimulate childbirth.