KA2 Hormone control of reproduction Flashcards
What are hormones?
Chemical messengers that are secreted into the blood stream
What controls the onset of puberty?
At the onset of puberty, the hypothalamus produces a releaser hormone which targets the pituitary gland
Which hormones are released from the pituitary gland?
FSH (men and women)
ICSH (men)
LH (women)
What does FSH promote in males?
FSH stimulates the production of sperm by the seminiferous tubules in the testes
What does ICSH promote in males?
ICSH stimulates the production of testosterone by the interstitial cells in the testes
What are the roles of testosterone?
Stimulates the production of sperm,
Stimulates the seminal vesicles and prostate gland to produce their secretion (semen)
What happens when there are high concentrations of testosterone?
At high concentrations it inhibits the secretion of FSH and ICSH by the pituitary gland, this is an example of negative feedback control
What are the four female hormones included in the menstrual cycle?
FSH (pituitary) Oestrogen (ovarian) LH (pituitary) Progesterone (ovarian) Think FOLP
How long does a woman’s menstrual cycle last?
28 days, the first day of menstruation is regarded as day one of the cycle
What does FSH do? (In women)
FSH stimulates the development/ maturation of a follicle within the ovary
FSH stimulates ovary cells to produce the hormone oestrogen
What does oestrogen do?
Oestrogen stimulates the proliferation of the endometrium preparing it for implantation of a blastocyst.
Oestrogen affects the consistency of cervical mucus making it more easily penetrated by sperm.
What stimulates a surge in the secretion of LH?
Oestrogen
What does LH do?
LH triggers ovulation
LH causes the development of the corpus lutuem
LH also stimulates the corpus lutuem to produce the hormone progesterone
What does progesterone do?
Progesterone stimulates the vascularisation of the endometrium into a spongy layer rich in blood vessels.
What is the negative feedback control in women?
Progesterone inhibits the secretion of FSH and LH from the pituitary gland. This prevents further follicles from developing.
What are the two stages of the menstrual cycle?
1- The follicular phase
2- The luteal phase
What happens during the follicular phase of the menstrual cycle?
FSH is released causing a follicle to develop and mature in the ovary.
Oestrogen is produced and causes the proliferation of the endometrium.
High levels of oestrogen trigger a surge in the release of LH, this causes ovulation and an egg is released into the oviduct. During the next three to four days fertilisation may occur if the egg meets a sperm.
What happens in the Luteal phase of the menstrual cycle?
LH stimulates the follicle to become the corpus lutuem which produces progesterone and oestrogen. Progesterone causes the vascularisation of the endometrium. High levels of progesterone has an inhibitory effect on the pituitary gland therefore concentrations of FSH and LH drop preventing any new follicles maturing during this time.
What is ovulation and when does it occur?
Ovulation is the releases of an egg (ovum) from a follicle in the ovary. It usually occurs around day 14 of the menstrual cycle.
What happens if fertilisation does not occur?
A lack in LH leads to the degeneration of the corpus lutuem. This results in a rapid drop in the concentrations of progesterone and oestrogen. By day 28 the levels of ovarian hormones are so low that the endometrium cannot be maintained and menstruation begins.
What happens if fertilisation occurs?
The corpus lutuem is maintained and progesterone levels remain high
