Hormonal Control of Reproduction

Question 1

Hormone

Answer 1

Chemical substance, produced by a gland and carried in blood, which alters activity of specific target organs (and is the destroyed by liver).

Question 2

Pituitary gland

Answer 2

‘Master gland’ situated at base of brain

Question 3

Examples of glands

Answer 3

Thyroid - thyroxine
Adrenal - adrenaline
Ovaries - Oestrogen
Testes - testosterone

Question 4

Hormones are involved in control of…

Answer 4

Onset puberty, menstrual cycle and sperm production

Question 5

Ages of puberty

Answer 5

10-16

Question 6

Changes occur during puberty due to…

Answer 6

hormones

Question 7

Onset of puberty

Answer 7

Hypothalamus gland in brain begins to secrete a releaser hormone which targets pituitary gland

Question 8

Releaser hormone stimulates pituitary gland to release what 2 hormones?

Answer 8

1. FSH follicle stimulating hormone
2. Interstitial Cell stimulating hormone ICSH / Luteinising hormone (LH)

Question 9

How do these hormones travel and where to?

Answer 9

Through blood to ovaries and testes

Question 10

In Males

Answer 10

ICSH stimulates testes to produce testosterone - causes development of male sexual organs and male secondary sexual characteristics

Question 11

In females

Answer 11

LH stimulates ovaries to produce oestrogen - causes development of female sexual organs and female secondary sexual characteristics

Question 12

FSH promotes/where

Answer 12

Sperm production in seminiferous tubules

Question 13

ICSH promotes what/where?

Answer 13

Interstitial cells to release testosterone

Question 14

Testosterone stimulates what/where

Answer 14

Sperm production in seminiferous tubules and activates prostate gland and seminal vesicles to produce their secretion

Question 15

Release of testosterone negative feedback system

Answer 15

1. build up of testosterone concentration in blood inhibits secretion of FSH and ICSH in pituitary gland
2. reduction of FHS and ICSH results in drop in production of testosterone
3. reduction of testosterone concentration in blood stops inhibition of ICSH and ICSH production
4. production and release of FSH and ICSH increases, stimulating increase production of testosterone.

Question 16

How long does menstrual cycle last?

Answer 16

28 days

Question 17

When is day one of menstrual cycle?

Answer 17

First day of period - blood - loss of lining of uterus with a limit

Question 18

Day 5 of menstruation

Answer 18

Loss of blood stops

The lining of uterus begins to re-grow and an egg cell starts to mature in one of the ovaries

Question 19

Around day 14 of menstruation

Answer 19

Mature egg is released form ovary - this is called ovulation. Egg travels through oviduct towards uterus

Question 20

If egg doesn’t meet a sperm cell in oviduct

Answer 20

Lining of uterus begins to break down and cycle repeats

Question 21

FSH

Answer 21

Causes the maturation of an egg in the ovary

pituitary gland

Question 22

LH

Answer 22

Stimulates release of egg

pituitary gland

Question 23

Oestrogen

Answer 23

Involved in repairing and thickening of uterus lining

ovaries

Question 24

Progestrone

Answer 24

Maintains uterus lining

Ovaries

Question 25

Oestrogen in cycle

Answer 25

Gradually increases and peaks approx on 12th day Drops days 13 and 14

Question 26

Progesterone in cycle

Answer 26

Stay approx at same level and begins to increase slightly from around day 12

Question 27

Menstrual cycle is controlled by negative feedback loop

Answer 27

1. The pituitary gland produces FSH which causes the development of a follicle in ovary 2. As egg develops inside the follicle, the follicle produces hormone oestrogen 3. Oestrogen causes growth and repair of lining of uterus wall. Oestrogen inhibits FSH 4. When oestrogen rises to a high enough level it causes a surge in LH from pituitary gland which causes ovulation where an egg is released from follicle (day 14 of cycle). 5. The follicle becomes the corpus luteum and this produces oestrogen and progesterone which inhibits FSH and LH production by pituitary. This is example of negative feedback. 6. progesterone maintains uterus lining 7. If egg fails to be fertilised, corpus luteum dies and progesterone levels drop. This causes menstruation, where the uterus lining breaks down - period

Question 28

If women becomes pregnant

Answer 28

Placenta produces progesterone This maintains lining of uterus during pregnancy and means menstruation does not happen