Physiology and Health: Hormonal Control of Reproduction

Question 1

What are hormones?

Answer 1

Chemical messengers that are produced by the endocrine glands

Question 2

Hormones are released directly into where?

Answer 2

The bloodstream and travel to their target tissue or organ where they have an effect

Question 3

Hormones control what?

Answer 3

The onset of puberty, sperm production and the menstrual cycle

Question 4

What happens at puberty?

Answer 4

The hypothalamus in the brain secretes a releaser hormone that targets the pituitary gland

Question 5

The pituitary gland is stimulated to release what two hormones in women and what one hormone in men?

Answer 5

Follicle stimulating hormone (FSH) and luteinising hormone (LH).
Interstitial cell stimulating hormone (ICSH)

Question 6

What hormones trigger the onset of puberty in females and in males?

Answer 6

In females, FSH and LH.

In males, ICSH.

Question 7

In males, FSH and ICSH do what?

Answer 7

FSH promotes sperm production in the seminiferous tubules of the testes.
ICSH stimulates the interstitial cells in the testes to produce the male sex hormone testosterone.

Question 8

What does testosterone also do?

Answer 8

Stimulates sperm production and activates the prostate gland and seminal vesicles to produce their secretions

Question 9

Overproduction of testosterone is prevented by what?

Answer 9

A negative feedback mechanism

Question 10

How does the negative feedback effect work on overproduction of testosterone?

Answer 10

High testosterone level inhibits the secretion of FSH and ICSH from the pituitary gland, resulting in a decrease in the production of testosterone by the interstitial cells

Question 11

The menstrual cycle takes approximately how many days and begins when?

Answer 11

Takes approximately 28 days.

With the first day of menstruation regarded as day one of the cycle.

Question 12

What hormones are associated with the menstrual cycle?

Answer 12

Pituitary hormones - FSH and LH

Ovarian hormones - Oestrogen and Progesterone

Question 13

What happens in the follicular phase (first half of the cycle)?

Answer 13

FSH stimulates the development and maturation of a follicle surrounding the ovum and the production of the sex hormone oestrogen by the follicle

Question 14

What does oestrogen do during the menstrual cycle?

Answer 14

It stimulates the repair and vascularisation of the endometrium, thickening it and preparing it for implantation. It also affects the consistency of the cervical mucus making it more easily penetrated by sperm.

Question 15

What does a peak level of oestrogen stimulate?

Answer 15

A surge in the secretion of LH by the pituitary gland

Question 16

In the luteal phase (second half of the cycle), this surge in LH triggers what?

Answer 16

Ovulation

Question 17

What is ovulation?

Answer 17

The release of an egg (ovum) from a follicle in the ovary

Question 18

When does ovulation occur?

Answer 18

Around the mid-point of the menstrual cycle

Question 19

What does LH also stimulate during the menstrual cycle?

Answer 19

The development of the corpus luteum from the follicle and stimulates the corpus luteum to secrete the sex hormone progesterone

Question 20

What does progesterone do?

Answer 20

Promotes further development and vascularisation of the endometrium preparing it for implantation if fertilisation occurs

Question 21

High levels of oestrogen and progesterone inhibit what?

Answer 21

The secretion of FSH and LH by the pituitary gland, which prevents further follicles from developing

Question 22

The inhibition of FSH and LH by high levels of oestrogen and progesterone is an example of what?

Answer 22

Negative feedback control

Question 23

The lack of LH leads to what?

Answer 23

The degeneration of the corpus luteum with a subsequent drop in progesterone level, leading to menstruation

Question 24

If fertilisation does occur, what happens to the corpus luteum?

Answer 24

It does not degenerate and progesterone level remains high