Biology - 11 Hormonal Coordination - 11.4 The Role of Negative Feedback & 11.5 Human Reproduction & 11.6 Hormones and the Menstrual Cycle

What is used to produce thyroxine?

iodine

What does thyroxine do? [2]

- regulates the basal metabolic rate
- affects the development of a child's brain

TSH

Thyroid Stimulating Hormone (thyrotropin)

What does TSH do?

stimulates thyroid to produce thyroxine

TRH

Thyrotropin Releasing Hormone

What releases TRH?

the hypothalamus

What releases TSH?

the pituitary gland

What does TRH do?

stimulates pituitary gland to release TSH

Why is adrenaline released?

in response to stressful or scary situations

What are the effects of adrenaline? [5]

- increase in heart rate and breathing rate
- glycogen converted to glucose for respiration
- pupils dilate to let in light
- mental awareness increases
- blood is diverted away from digestion and to limb muscles

How does adrenaline cause effects?

boosts delivery of oxygen and glucose to brain and muscles

Oestrogen

main female reproductive hormone, produced in the ovaries

What does oestrogen do? [2]

- triggers gradual changes of puberty
- involved in menstruation

Ovulation

release of an egg from the ovary

FSH

Follicle Stimulating Hormone

What does FSH do? [2]

- causes eggs to mature
- stimulates oestrogen release

LH

Luteinising Hormone

What does LH do? [2]

- causes ovulation
- forms corpus luteum (empty follicle)

What does oestrogen do in the menstrual cycle? [3]

- thickens uterine lining
- inhibits FSH
- (in high levels) stimulates release of LH

What does progesterone do in the menstrual cycle?

- maintains uterine lining
- inhibits FSH and LH

Testosterone

main male reproductive hormone, produced in the testes

Stage 1 of the menstrual cycle

menstruation

Stage 2 of the menstrual cycle

uterine lining starts to build up

Stage 3 of the menstrual cycle

ovulation

Stage 4 of the menstrual cycle

maintaining the lining of the uterus

How do levels of oestrogen vary throughout the cycle? [2]

- rise until ovulation to develop uterine lining and stimulate release of LH
- fall as lining maintains and menstruation starts

How do levels of progesterone vary throughout the cycle? [2]

- stays constant until rising in stage 4 to maintain lining and inhibit FSH and LH
- falls to begin menstruation

How do levels of FSH vary throughout the cycle? [3]

- raises in stage 1 to cause release of oestrogen
- falls in stage 2 due to oestrogen inhibiting
- low peak at ovulation, when egg matures

How do levels of LH vary throughout the cycle? [2]

- stay constant most of cycle
- peak at stage 3, causing ovulation