BIOL 110 Lecture Notes - Vas Deferens, In Vitro Fertilisation, Spermicide
Document Summary
At birth, progesterone levels fall prolactin levels increase. Breastfeeding promotes production of milk by positive feedback: nerve impulses travel to hypothalamus, stimulates pituitary gland to secrete oxytocin and prolactin, the more milk is removed, the more hormones are secreted. Oxytocin: stimulates contraction of milk ducts squeezes milk out. Inhibits secretion of fsh and lh prevents ovulation less likely to conceive. 99% effective (<1:100 women will get pregnant in a year) Progestogen-only pill: thickens cervical mucus reduces sperm motility. Inhibits lh production may prevent ovulation (depends on dose) Long-acting progestogen can be given for up to 3mo by injection. Morning-after pill: contains high doses of progestogen, works for up to 72h after intercourse - works best within 12h. Inserted into uterus for up to 10yrs: stimulates release of prostaglandins by endometrium, copper kills sperm. Risk of ectopic pregnancy (ovulation not inhibited) and infection.
