hormonal control of reproduction 2.2

Question 1

hormones

Answer 1

chemical messengers produced by endocrine glands, they secreted directly into the bloodstream and travel to their target tissue where they bring about specific responses

Question 2

what do hormones control

Answer 2

onset of puberty, sperm production and the menstrual cycle

Question 3

what is puberty

Answer 3

the sequence of physical changes in which a child’s body develops into an adult, capable of reproduction

Question 4

what happens at puberty

Answer 4

the hypothalamus secretes a released hormone that targets the pituitary gland

Question 5

what are the two hormones the pituitary gland secretes in males

Answer 5

FSH and ICSH

Question 6

what are the two hormones the pituitary gland secretes in females

Answer 6

FSH and LH

Question 7

what does FSH promote in males

Answer 7

sperm production in the seminiferous tubules

Question 8

what does ICSH stimulate in males

Answer 8

the interstitial cells to produce testosterone

Question 9

what does testosterone stimulate

Answer 9

the seminiferous tubules to produce sperm and activates the prostate gland and the seminal vesicles to produce their secretions

Question 10

negative feedback control of testosterone

Answer 10

high concentration of testosterone inhibit the pituitary gland from secreting FSH and ICSH so interstitial cells produce less testosterone

Question 11

how long is the menstrual cycle

Answer 11

approximately 28 days

Question 12

the 2 phases of the menstrual cycle

Answer 12

the follicular phase and luteal phase

Question 13

the follicular phase

Answer 13

-FSH stimulates the development of the follicle and the production of oestrogen by the follicle
-oestrogen stimulates the proliferation of the endometrium to prepare it for implantation, it also affects the consistency of the cervical mucus making it more easily penetrated by sperm
-around day 14 (midpoint of the menstrual cycle) peak levels of oestrogen stimulates a surge of LH released by the pituitary gland
-the surge of LG triggers ovulation which is the release of an egg (ovum) from the follicle in the ovary
-the ovum moves slowly along the oviduct and in the next 3/4 days fertilisation may occur

Question 14

the luteal phase

Answer 14

-LH also stimulates the follicle to develop into the corpus luteum which secretes progesterone
-progesterone promotes further development and vascularisation of the endometrium preparing it for implantation of a blastocyst if fertilisation occurs
-progesterone causes thickening of the cervical mucus preventing sperm from entering and protection the blastocyst from infection

Question 15

negative feedback in women

Answer 15

-high levels of progesterone inhibits the secretion of FSH and LH by the pituitary gland
-lack of FSH prevents further development of the follicle
-lack of LH leads to degeneration of the corpus luteum which had a subsequent drop in progesterone levels
-by day 22 these hormone levels are so low that the endometrium breaks down and triggers the start of menstruation

Question 16

pregnancy

Answer 16

-if fertilisation (and therefore pregnancy) occurs the corpus luteum does not degenerate and continues to produce progesterone which maintains the endometrium and prevents miscarriage
-the placenta then takes over the production of progesterone a few weeks into pregnancy