Physiology and Health Unit 2 KA 2 Flashcards
Hormonal Control of Reproduction
What is a Hormone?
A Hormone is a chemical that is produced at one site, and has an effect at another site
What produces Hormones?
Hormones are produced by endocrine glands and are secreted directly into the blood stream
What happens when a Hormone reaches a target tissue?
When a Hormone reaches a target tissue, it brings about a specific effect
Hormones produced in the ____ and the ____ ____ control what? (3)
(Fill in the blanks)
Hormones produced in the Hypothalamus and the Pituitary gland control:
the onset of puberty, sperm production, the menstrual cycle
At puberty, the Hypothalamus secretes a releaser hormone, what is the target?
At puberty, the Hypothalamus secretes a releaser hormone whose target is the pituitary gland
What three hormones does the Pituitary gland release?
1) Follicle-stimulating hormone (FSH) (M+F)
2) Interstitial cell-stimulating hormone (ICSH) (M)
3) Luteinising hormone (LH) (F)
What does the hormone FSH promote in males? Where does this occur?
FSH promotes sperm production in the seminiferous tubules (in the testes)
What does the hormone ICSH promote in males? Where does this occur?
ICSH stimulates the interstitial cells to produce testosterone (male sex hormone)
This happens in the testes
What does Testosterone stimulate?
Testosterone stimulates sperm production in the seminiferous tubules, it activates the prostate gland and seminal vesicles to produce their secretions
How is Testosterone production regulated?
Testosterone production is regulated by a negative feedback control
As the concentration increases in the bloodstream, it reaches a level where it inhibits the production of FSH and ICSH by the pituitary gland, leading to a decrease which then triggers the pituitary gland to produce more hormones again
How long is the Menstrual cycle? (approx)
The Menstrual cycle is approximately 28 days long
How is Menstruation indicated?
Menstruation is indicated by blood flow
What are the two stages of the Menstrual cycle?
1) Follicular phase
2) Luteal phase
What does the hormone FSH stimulate in females? Where?
FSH stimulates the development and maturation of each follicle
It also stimulates the production of oestrogen by the follicle in the Follicular phase (1st)
This occurs at the ovaries
What does the hormone LH trigger in females? Where?
LH triggers ovulation and brings about the development of the corpus luteum from the follicle (after ovulation)
It also stimulates the corpus luteum to secrete progesterone (female sex hormone)
What happens when the ovary wall secretes Oestrogen? (4)
As the concentration of Oestrogen builds up it stimulates proliferation (cell division) and repair of the endometrium following menstruation
2) Alters cervical mucus - becomes thin and watery so it is more easily penetrated by sperm
3) Peak levels of oestrogen stimulates a surge in the secretion of LH by the pituitary gland (approx day 14 of cycle)
4) Surge in LH triggers ovulation
What does Progesterone do? (2)
1) Promotes the further development of the endometrium, preparing it for implantation
2) Inhibits the secretion of FSH and LH by the pituitary gland
How many days are women fertile for?
Women are fertile for 2-3 days
When fertilisation occurs, the Embryo secretes a hormone called HCG, what does this do?
HCG has the same effect as LH
It maintains the corpus luteum so it doesn’t degenerate and will continue to secrete progesterone
This prevents menstruation from taking place
If fertilisation doesn’t occur, what happens to the Corpus luteum?
If fertilisation doesn’t occur the corpus luteum will degenerate because of the lack of LH
The lack of LH leads to a subsequent drop in progesterone and oestrogen
This leads to menstruation
