Sex Hormones W4

Question 1

The male reproduction system

Answer 1

Brain secretes hormones that control the testes and this is the hypothalamus

Hormone is secreted and circulates the anterior pituitary which secreted 2 hormoes to target the testes. This is the brain testicular axis

Question 2

What is secreted by the hypothalamus

Answer 2

GNRH which targets the interior pituitary which circulates and causes the anterior to release LH and FSH which circulate to the testes and control testicular secretion

Question 3

2 main structural components of the testes

Answer 3

Interstitial cells - fill the gaps between the seminiferous tubules and produce testosterone

Seminiferous tubules = site of sperm production

Question 4

LH

Answer 4

Stimulates interstitial cells in testes to produce testosterone which them drives spermogenesis and maintain 2ndary sex characteristic

Question 5

FSH

Answer 5

Stimulates seminiferous cells which are found in the tubules and stimulate these cells to release androgen binding ATP. This enhances thr ability of the sperm to bind to testosterone

Question 6

Female reproductive system

Answer 6

Same as in males : GnRH to anterior to produce LH and FSH

But these will then travel to the ovaries

Ovaries have blood vessels and through capillaries the hormoes can enter

Question 7

Ovaries

Answer 7

In each there are follicles and each month some will mature into primary follicles and continue maturing but only one will ovulate

Question 8

Menstrual cycle phases

Answer 8

1. Folicular
2. Luteal

Question 9

Folicular phase

Answer 9

is the first phase and follicle stimulating hormonal into the ovaries

essentially they will stimulate full maturation of the primary molecules and so some of the primary follicles were mature into secondary follicles

While they are maturing they produce oestrogen in the first 10 days of the menstrual cycle.

Question 10

Oestrogen effect

Answer 10

Negative feedback on pituitary and inhibitors the release of LH

Makes a steady level of LH even though there is an increase in GnRH

Question 11

FSH women

Answer 11

Secreted primarily in response to low oestrogen

When oestrogen rises, FSH will fall

As follicles mature they produce more oestrogen and so this rise will cause decrease in FHSH

Question 12

Peripheral effects of oestrogen

Answer 12

Stimulating bone and muscle growth and stimulating endometrial growth and maintain female 2ndary characteristics and glands

Question 13

After 10 days women

Answer 13

Oestrogen continue to rise and follicles matures

After these 10 days the oestrogen rises and will have positive feedback and stimulate release of LH

Question 14

At low concentrations, oestrogen will……. LH secretion, but at high concentrations oestrogen will……LH secretion

Answer 14

Inhibit

Stimulate

Question 15

What triggers ovulation of the most mature follicle

Answer 15

Spike in LH conc

So LH triggers ovulation and an egg is released after

Question 16

After ovulation

Answer 16

The follicle will turn into corpus luteal - a dead follicle

It will slowly degrade but still has purpose as it secretes oestrogen, progesterone and inhibin

Question 17

oestrogen, progesterone and inhibin

Answer 17

Oestrogen increase until ovulation and then drop slightly., inhibin wasn’t present until after ovulation and then begins to increase and progesterone levels were low until after ovulation during the luteal phase.

Question 18

At 21 days

Answer 18

Progesterone is increasing

Inhibin is increasing and has neg feedback and will inhibit the secretion of FSH - we dont want anymore follicles to mature

Oestrogen is still detectable

Question 19

As the 2ndary luteal corpus develops….

Answer 19

Inhibin secretion will suppress FSH

Question 20

Most important hormoe in the luteal phase ?

Answer 20

Progesterone

Has many functions including having a neg feedback on hypothalamus, inhibiting GnRH secretion

Progesterone increases slowly after ovulation and oestrogen decreases and this suppresses GnRH

Question 21

Main effect of progesterone

Answer 21

Stimulate endometrial growth and endometrial lining is of the uterus which sheds each month or it is where the egg implants if fertilised

Question 22

If there is no fertilisation

Answer 22

Corpus luteum in the ovary will degenerate, allowing a new set of follicles to mature and its hormones will also decrease

Question 23

When the corpus degenerates…

Answer 23

Progesterone will decrease and so cannot inhibit GnRH secretion and so this will increase and allow a new menstrual cycle to occur

Question 24

The decrease in progesterone and oestrogen causes

Answer 24

Uterus to shed as cannot maintain the lining - have a period and a new cycle begins

Question 25

Prolactin

Answer 25

Inhibited by dopamine and stimulates milk secretion but also has effects in:
- decreasing gonadal activity by decreasing GnRH
- hyperprolactinaemia