Hormones

Hormones

chemical substances secreted by glands that help to regulate processes in the body

homeostasis

maintaining a constant internal environment in the body

What controls the internal environment?

hormones and the nervous system

FSH
(hormones of the menstrual cycle)

produced by the pituitary gland
1. causes the egg to mature in the ovary
2. stimulates the ovaries to release the hormone oestrogen

oestrogen
(hormones of the menstrual cycle)

produced by the ovary
1. stops the production of FSH so only 1 egg matures per cycle
2. stimulates pituitary gland to produce the hormone LH

LH

produced in the pituitary gland
causes the mature egg to be released from the ovary

oral contraceptive (the pill)

contains oestrogen or oestrogen and progesterone which inhibits the production of FSH in the pituitary so no eggs can mature in the ovaries

Fertitlity drugs

contain FSH which stimulates eggs to mature in the ovary

IVF

the egg is fertilised outside the woman's body and then implanted in the uterus

problems with oral contraceptive

changes in weight, mood, blood pressure
increased risk of blood clots

problems with fertility drugs

multiple conceptions (twins, triplets) may lead to problems in pregnancy and childbirth which may lead to premature or underweight babies

problems with IVF

ethical problems with parents choosing 'desirable' traits or the sex of their child