3.2 - Hormones and the Menstrual Cycle

whyyyyy do periods even HAPPEN ahhhh

What is a hormone?

a chemical messenger made and released by an endocrine gland into the blood which has an effect on a specific organ

What hormones involved in the menstrual cycle are secreted by the pituitary gland?

FSH, LH

What hormones involved in the menstrual cycle are secreted by the ovaries?

oestrogen, progestrone

What does the FSH do?

• causes eggs to mature

• stimulates ovaries to produce estrogen

What does LH do?

causes egg to be released from the ovary

What does oestrogen do?

• stimulates growth of uterus lining

• stops FSH being produced to ensure that only one egg matures in a cycle

• stimulates the pituatary gland to release LH

What does progestrone do?

• inhibits both FSH and LH production to keep the body ready for pregnancy until it is clear the egg is not fertilised

• maintains uterus lining during middle part of menstrual cucle and during pregnancy

What is Day 1-5 of the Menstrual Cycle called?

menstruation

What happens at Day 1-5 of the menstrual cycle?

• uterus lining is broken down

• FSH levels rise, stimulating the egg to mature

What happens on Day 7-13 of the menstrual cycle?

• As FSH levels rise, oestrogen levels rise

• Uterus lining starts to thicken

• Rising oestrogen, causes decrease in FSH (prevents more eggs developing)

• LH levels increase

What happens on Day 13-15 of the menstrual cycle?

LH levels reach a peak and ovulation occurs

What happens on Day 15-28 of the menstrual cycle?

• oestrogen levels decrease, progestrone increases

• uterus lining thickens

• FSH/LH inhibited

What happens on Day 28 of the menstrual cycle?

• if egg is fertilised: oestrogen and progestrone levels stay high

• if egg is not fertilised: uterus lining breaks down