Unit 2.2 - Hormonal Control Of Reproduction

Question 1

How long does the menstrual cycle approximately take?

Answer 1

28 days with the first day of menstruation regarded as day one of the cycle

Question 2

What are the two phases of the menstrual cycle?

Answer 2

Follicular phase - development of a follicle and ovulation

Luteal phase - development of the corpus luteum and menstruation

Question 3

Describe the follicular stage ( first half of cycle)

Answer 3

• Pituitary gland releases FSH
• FSH stimulates follicle development and maturation and production of oestrogen
• Oestrogen stimulates proliferation of the endometrium preparing it for implantation and effects the consistency of cervical mucas making It more easily penetrated by sperm
• peak levels of oestrogen stimulate a surge in the secretion of LH, which triggers ovulation

Question 4

Describe the luteal phase ( second half of the cycle)

Answer 4

LH stimulates follicle to form corpus luteum
Corpus Luteum secretes progesterone
Progesterone promotes further development and vascularisation of the endometrium and inhibits the pituitary gland
FSH and LH levels drop
Lack of LH causes the corpus luteum to breakdown
Progesterone levels decrease
By day 28 in the cycle progesterone is so low the endometrium cannot be maintained and menstration begins

Question 5

What does FSH do in females?

Answer 5

• Stimulates the development of the follicle

* Stimulates the production of oestrogen by the follicle in the follicular phase

Question 6

What does LH do?

Answer 6

Triggers ovulation

Question 7

What does FSH and LH trigger the ovaries to produce?

Answer 7

Oestrogen and progesterone

Question 8

What is ovulation?

Answer 8

The release of an egg from a follicle in the ovary, usually occurring around mid point of the menstrual cycle

Question 9

What happens if fertilisation does occur?

Answer 9

The corpus luteum does not degenerate and progesterone levels remain high

Question 10

What happens when the pituitary gland is stimulated?

Answer 10

•FSH and LH (females) or ICSH( males)
Is released by the released hormone produced in the hypothalamus
•This triggers the onset of puberty

Question 11

What does FSH, LH and ICSH Stand for?

Answer 11

FSH - follicle stimulating hormone
ICSH - Interstitial cell stimulating hormone
LH - luteinising hormone

Question 12

What does FSH do in males?

Answer 12

Promotes speed production

Question 13

What does ICSH do?

Answer 13

Stimulates the production of testosterone

Question 14

What does testosterone do?

Answer 14

• Stimulates sperm production

* Activated the prostate gland and seminal vesicles

Question 15

Describe the negative feedback mechanisms for controlling testosterone

Answer 15

• Build up of testosterone concentration in the blood inhibits the secretion of FSH and ICSH from the pituitary gland
• Reduction of FSH and ICSH results in drop in production of testosterone
• Reduction of testosterone concentration in the blood stops inhibition of FSH and ICSH production
• The production and release of FSH and ICSH increases, stimulating increased production of testosterone