Unit 2 KA2 - hormonal control on reproduction Flashcards
what is a hormone?
a chemical that is produced at one site and has an effect on another
produced by endocrine glands and secreted directly into the bloodstream
brings about a specific effect when it reaches a target tissue
describe the hormonal onset of puberty
the hypothalamus produces a releaser hormone whose target is the pituitary glans
the pituitary gland is stimulated to produce the hormones;
- follicle-stimulating hormone (male + female)
- interstitial cell-stimulating hormone (male)
- luteinising hormone (female)
the release of FSH and ICSH triggers the onset of sperm production in men and the release of FSH and LH triggers the onset of the menstrual cycle in women
what is the role of FSH in the hormonal control of sperm production?
FSH arrives in the bloodstream at the testes and promotes sperm production in the seminiferous tubules
what is the role of ICSH in the hormonal control of sperm production?
ICSH arrives in the bloodstream at the testes and stimulates the interstitial cells to produce the male sex hormone testosterone
……. arrives in the bloodstream at the…….. and stimulates the…………to produce the male sex hormone…………
ICSH, testes, interstitial cells, testosterone
what is the role of testosterone?
stimulates sperm production in the seminiferous tubules and activates the prostate gland and seminal vesicles to secrete fluids which maintain the mobility and viability of sperm
describe negative feedback control of testosterone by FSH and ICSH
as the concentration of testosterone builds up in the bloodstream, it reaches a level where it inhibits the secretions of FSH and ICSH from the pituitary gland
this leads to a decrease in testosterone concentration, which then triggers the pituitary gland to again make FSH and ICSH, and so on
how many days does the menstrual cycle last?
name the stages
28 days, 1 - follicular phase, 2 - luteal phase
describe the hormonal control of the menstrual cycle in stage 1
in the follicular phase, FSH levels increase which stimulates:
1 - development and maturation of a follicle
2 - production of oestrogen by the follicle
oestrogen promotes:
1 - proliferation of the endometrium
2 - reduces the viscosity of cervical mucus making it easier for sperm to penetrate
3 - towards the end of the phase has a stimulatory effect on the pituitary’s production of LH and FSH (positive feedback)
4 - on day 14 oestrogen triggers LH surge and ovulation occurs
describe the hormonal control of the menstrual cycle in stage 2
in the luteal phase, LH stimulates the follicle to develop into the corpus luteum
the corpus luteum secrete progesterone
the rise in progesterone concentration stimulates further development of the endometrium and increases vascularisation, preparing it for implantation if fertilisation has occurred
describe negative feedback control in the second stage of the menstrual cycle
negative feedback control of the pituitary hormones by the ovarian hormones prevents the development of more follicles
the low levels of LH cause the corpus luteum to degenerate which leads to a decrease in progesterone, which leads to the endometrium no longer being maintained, which leads to menstruation
what happens to the corpus luteum if fertilisation occurs?
it does not degenerate and mains high progesterone levels
what happens at the midpoint of the menstrual cycle?
ovulation
what is ovulation?
the release of the egg from a follicle in the ovary
the ovum moves along the oviduct and over 2-3 days, fertilisation may occur if the ovum meets a sperm
where is FSH secreted?
pituitary gland
