2.2- hormonal control of reproduction

Question 1

what are hormones?

Answer 1

chemical messengers produced by endocrine glands and secreted directly into the bloodstream

Question 2

3 things hormones control

Answer 2

onset of puberty

sperm production

menstrual cycle

Question 3

what happens at the onset of puberty?

Answer 3

the hypothalamus secretes a releaser hormone which acts on the pituitary gland

Question 4

what is stimulated for hormones to be released?

Answer 4

the pituitary gland

Question 5

2 hormones that influence puberty in males

Answer 5

FSH- follicle stimulating hormone

ICSH- interstitial cell stimulating hormone

Question 6

2 hormones that influence puberty in females

Answer 6

FSH- follicle stimulating hormone

LH- luteinising hormone

Question 7

what do FSH and ICSH trigger in males?

Answer 7

sperm production

Question 8

what does FSH and LH trigger in females?

Answer 8

menstrual cycle

Question 9

what does FSH do when it arrives in the bloodstream?

Answer 9

promotes sperm production in the seminiferous tubules

Question 10

what does ICSH do when it arrives in the bloodstream?

Answer 10

stimulates the interstitial cells to produce the male sex hormone testosterone

Question 11

2 functions of testosterone

Answer 11

stimulates sperm production in the seminiferous tubules

activates prostate gland and seminal vesicles to produce their secretions

Question 12

how is testosterone regulated and what by?

Answer 12

self regulated

by negative feedback control

Question 13

what happens when the concentration of testosterone builds up in the bloodstream?

Answer 13

testosterone concentration reaches a level where it inhibits the secretion of FSH and ICSH from the pituitary gland

Question 14

what does the inhibition of the secretion of FSH and ICSH lead to and what happens?

Answer 14

leads to a decrease in testosterone concentration

then the pituitary gland becomes active again and making FSH and ICSH

Question 15

where does FSH and LH come from?

Answer 15

pituitary gland

Question 16

2 functions of FSH in the follicular phase

Answer 16

stimulates the development and maturation of each follicle

stimulates ovary tissue to secrete the sex hormone oestrogen

Question 17

what is the name given to the lining of the uterus?

Answer 17

endometrium

Question 18

2 functions of oestrogen

Answer 18

stimulates proliferation of the endometrium preparing it for implantation

affects the consistency of cervical mucus

Question 19

what effect does the thin consistency of the cervical mucus have?

Answer 19

mucus more easily penetrated by sperm

Question 20

what happens at peak levels of oestrogen and what is triggered?

Answer 20

surge of LH is stimulated

triggers ovulation

Question 21

what is ovulation and when does it occur?

Answer 21

release of an egg from a follicle in the ovary

often occurs around the midpoint of the menstrual cycle (day 14)

Question 22

2 phases of the menstrual cycle

Answer 22

follicular phase (1 - 13)

luteal phase (15 - 28)

Question 23

what 2 things happens to the follicle in the luteal phase?

Answer 23

develops into a corpus luteum

secretes progesterone

Question 24

what does progesterone do and what effect does it have?

Answer 24

promotes further development and vascularisation of the endometrium

this prepares endometrium for implantation if fertilisation occurs

Question 25

what is triggered during the luteal phase and what by?

Answer 25

an inhibitory effect (negative feedback control) on the pituitary gland

triggered by the combined high levels of oestrogen and progesterone

Question 26

what 2 things happen as a result of the inhibitory effect on the pituitary gland?

Answer 26

concentrations of FSH and LH drop

no new follicle develops at this time

Question 27

2 things that happen if fertilisation does not occur during the luteal phase

Answer 27

lack of LH leads to the degeneration of the corpus luteum with a subsequent drop in progesterone levels

hormones at such a low level by day 28 that endometrium can no longer be maintained and menstruation begins

Question 28

approximately when is the corpus luteum degenerated?

Answer 28

day 22

Question 29

what is menstruation?

Answer 29

loss of the inner layer of the endometrium accompanied by a small volume of blood

Question 30

2 things that happen if fertilisation does occur during the luteal phase

Answer 30

embryo secretes a hormone that maintains the corpus luteum

corpus luteum does not degenerate and progesterone levels remain high which prevents menstruation from taking place

Question 31

what does the placenta do and when?

Answer 31

begins secreting progesterone at about 6 weeks