1. WALT ; Describe how the menstrual cycle works All can identify the 4 hormones involved. Most can describe how they regulate the menstrual cycle Some can explain how the negative feedback mechanism controls the menstrual cycle

2. The menstrual cycle?

3. Fertility 3 hormones are involved in the menstrual cycle: oestrogen, LH and FSH. Here’s how: Step 3: LH stimulates the release of the mature egg in the middle of the menstrual cycle Artificial fertility: 1)To INCREASE fertility FSH is given to stimulate maturation of eggs. 2)To DECREASE fertility oestrogen is given (“The Pill”) to inhibit FSH production stopping eggs from maturing. Step 1: FSH produced by the pituitary gland causes both an egg to mature and the ovaries to start producing oestrogen Step 2: The rising levels of oestrogen cause the pituitary gland to stop producing FSH and produce LH instead

4. Inside the ovary What happens in the ovary during the menstrual cycle? Day 1-13: egg developing inside the growing follicle Day 14: ovulation – egg released from follicle Day 15-28: empty follicle turns into corpus luteum (yellow body) immature eggs

5. Uterus lining The lining of the uterus becomes thicker with blood vessels and more stable during the menstrual cycle. Why is this important? 210684121416182022242628 days after start of period uterus lining thickness period A fertilized egg will bury itself (implant) in the uterus lining. The egg needs a plentiful supply of oxygen and nutrients to develop.

6. Hormone levels

7. Pregnancy If the egg is fertilized, the uterus lining must not break down otherwise the fertilized egg will not develop. corpus luteum: continues to produce progesterone and oestrogen egg fertilized: uterus lining maintained, egg implanted progesterone memo To: uterus From: corpus luteum Maintain uterus lining. oestrogen memo To: pituitary From: corpus luteum Don’t send FSH.

8. How does the contraceptive pill work? progesterone memo To: pituitary From: contraceptive pill Stop sending FSH. Contraceptive pills contain progesterone and need to be taken every day. How do they work? no FSH received: no egg maturing Contraceptive pills mimic pregnancy, which means that the ovaries do not produce any eggs.

9. Summary of fertility hormones