Hormonal Control Of Reproduction

Question 1

What are hormones ?

Answer 1

They are chemical messengers which travel in the bloodstream to their target tissue which has specific receptors. They are produced in endocrine glands

Question 2

What do hormones play a pivotal role in?

Answer 2

Sexual reproduction in both male and females.

Question 3

What do hormones control?

Answer 3

The onset of puberty

Question 4

What is puberty?

Answer 4

The process of physical changes through which a child’s body matures into an adult body capable of sexual reproduction

Question 5

What is puberty initiated by?

Answer 5

Hormonal signals

Question 6

What is the pituitary gland stimulated to release?

Answer 6

Follicle-stimulating hormone, luteinising hormone (females) or interstitial cell stimulating hormone (males) by a releaser hormone produced in the hypothalamus

Question 7

What does FSH do in terms of males?

Answer 7

Promotes sperm production

Question 8

What does ICSH stimulate in terms of males?

Answer 8

The production of testosterone

Question 9

What does testosterone also stimulate?

Answer 9

Sperm production (by stimulating meiosis in seminiferous tubules) and activates secretion from the prostate gland and seminal vesicles

Question 10

Describe negative feedback control?

Answer 10

The body has self-regulating mechanisms, called negative feedback that allows the body to correct changes. When a factor affecting the body’s internal environment deviates from the norm (or set point), the body responds to correct the change

Question 11

What happens if the concentration of testosterone gets to a high level?

Answer 11

It inhibits the secretion of FSH and ICSH, which decreases the testosterone concentration.

Question 12

In males what is the LH the same as ?

Answer 12

ICSH

Question 13

What does the pituitary gland release in females?

Answer 13

FSH and LH

Question 14

How does FSH affect the ovaries ?

Answer 14

Stimulates the development and maturation of each follicle . It also stimulates follicular tissue to secrete oestrogen

Question 15

When oestrogen reaches high levels I.e its peak what happens ?

Answer 15

It stimulates a surge in LH by the pituitary gland

Question 16

What does LH do?

Answer 16

Triggers ovulation.
It also brings about the development of the corpus luteum from the old follicle and stimulates the secretion of progesterone and some oestrogen

Question 17

What does oestrogen do in terms of hormonal control of the menstrual cycle?

Answer 17

Stimulates the proliferation of the endometrium thereby effecting its repair following menstruation and preparing it for implantation of a blastocyst e.g. thickening

In high levels it stimulates a surge in LH by the pituitary gland

Question 18

What does progesterone do in terms of the hormonal control of the menstrual cycle?

Answer 18

Promotes further development and vascularisation of the endometrium into a spongy layer rich in blood vessels, making it ready to receive a blastocyst (should fertilisation occur).
In high levels it inhibits the secretion of FSH &à LH

Question 19

How long does the menstrual cycle usually last?

Answer 19

approx 28 days

Question 20

What is first day of the cycle?

Answer 20

the first day of a woman’s period (menstruation)

Question 21

How long does the period usually last?

Answer 21

for 3-7 days

Question 22

What is the period made up of?

Answer 22

blood and the endometrium

Question 23

What happens to the period?

Answer 23

it passes out of the body through the vagina

Question 24

What are the 2 phases the menstrual cycle is divided into?

Answer 24

Follicular phase (1st) 
Luteal phase (2nd)

Question 25

What happens as the concentration of oestrogen builds?

Answer 25

it brings about the repair and proliferation of the endometrium following the previous menstruation

Question 26

What does a high concentration of oestrogen (peak) trigger?

Answer 26

a surge in the production of LH and FSH at anout day 14.

Question 27

What does a surge in LH cause?

Answer 27

ovulation

Question 28

What happens when the egg is released and how long can it survive and what does this mean for fertilisation?

Answer 28

it slowly moves along the oviduct & can survive for only 1-2 days. However, sperm can survive for 3-4 days and so fertilisation may occur in 3-4 day window each month.

Question 29

What is fertility in terms of females?

Answer 29

cyclically fertile

Question 30

What does high levels of progesterone and oestrogen trigger?

Answer 30

an inhibitory effect on the pituitary gland. Concentrations of FSH and LH drop (and no new follicles develop

Question 31

What does the lack of LH due to the inhibition by progesterone lead to?

Answer 31

the degeneration of the corpus luteum by about day 22. Hence the levels of oestrogen and progesterone drop

Question 32

What happens by day 28 in terms of the endometrium?

Answer 32

the levels of oestrogen and progesterone are so low that the endometrium can no longer be maintained and starts to break down (menstruation begins)