Hormones In The Human Reproductive System

Question 1

Stage 1 of the Menstrual Cycle

Answer 1

• First day of period (day 1)

- Usually lasts anywhere from 3-7 days

Question 2

Stage 2 of the Menstrual Cycle

Answer 2

• At the beginning - FSH (follicle stimulating hormone) is released, after being produced in the pituitary gland
• FSH - stimulates ovaries to produce mature eggs

Question 3

Stage 3 of the Menstrual Cycle

Answer 3

• FSH stimulates a number of follicles to develop and produce oestrogen
• Level of oestrogen is lowest on the first day of periods and increases as the follicle reaches oestrogen

Question 4

Stage 4 of the Menstrual Cycle

Answer 4

• Level of oestrogen is still increasing
• Eventually causes a rapid rise in the LH (luteinising hormone) ‘LH surge’ but inhibits the production of FSH
• Causes the dominant follicle to rupture + release a mature egg from the ovaries, where it enters the Fallopian tube. OVULATION BEGINS

Question 5

Stage 5 of the Menstrual Cycle

Answer 5

• As soon as you’ve ovulated, the empty follicle start to produce progesterone

Question 6

Stage 6 of the Menstrual Cycle

Answer 6

• Progesterone causes the further build up of the lining of your uterus, in preparation for a fertilised egg

Question 7

Stage 7 of the Menstrual Cycle

Answer 7

• As the empty follicle shrinks (the egg isn’t fertilised), levels of progesterone decrease
• Without high levels of progesterone, the thick womb lining stats to break down.
• The body sheds this lining, marking the start of your period + menstrual cycle

Question 8

FSH:

• where is it produced
• what does it do in the menstrual cycle
• target organ?

Answer 8

• Produced in pituitary gland
• Stimulates ovaries to produce mature eggs
• Target organ: Ovaries

Question 9

Oestrogen:

• where is it produced
• function in the menstrual cycle
• target organ?

Answer 9

• Made by follicles in the ovaries
• Stimulates the production of LH, inhibits the production of FSH
• Target organ : Pituitary gland

Question 10

LH:

• where is it produced
• what is it’s function in the menstrual cycle
• target organ?

Answer 10

• Made in the pituitary gland
• Causes the dominant follicle to rupture and release a mature egg
• Target organ: Ovaries

Question 11

Progesterone:

• where is it produced
• what is it’s function in the menstrual cycle
• target organ?

Answer 11

• Produced in the empty follicle (CORPEUS LUTEUM)
• Causes further build up of the uterus’ lining for another fertilised egg
• Target Organ: Uterus

Question 12

High levels of oestrogen inhibit the production of FSH in the pituitary gland.
Explain how this is an example of negative feedback.

Answer 12

• As the follicle becomes CORPUS LEUTEM, more oestrogen and progesterone are produced, sending signals to the pituitary gland to not produce more FSH

Question 13

What does IVF stand for?

Answer 13

In Vitro Fertilisation- fertilisation in the laboratory outside the mother’s body

Question 14

How can clomiphene be used to treat infertility?

Answer 14

• This drug causes more FSH and LH to be released by the body, stimulating egg maturation and ovulation
• By knowing when the woman will be ovulating, a couple can improve their chances of pregnancy by trying for a baby near to ovulation

Question 15

What are the steps of IVF?

Answer 15

• A drug is given to suppress the production of FSH and LH - stops the usual cycle of egg maturation + ovulation
• A larger dose of LH is given - causes many egg cells to grow and mature in both ovaries
• A larger dose of FSH is given everyday for several days - completes egg maturation, so that many mature eggs are released at once
• While the egg cells are in the lab, progesterone is given - prepares the uterus for an embryo, by thickening it’s lining

Question 16

What are some other methods of contraception?

Answer 16

• Oestrogen - produced in high amounts, inhibits the production of FSH, stopping egg development + production after a while
• Progesterone - stimulates the production of thick cervical mucus, prevents sperm getting through to the cervix and uterus
• Combined pill of oestrogen and progesterone
• Physical barriers - eg: condoms, diaphragms- fit over uterus opening (used with spermicide to kill sperm)