Unit 2.2 Hormonal Control of Reproduction Flashcards
What are hormones
Chemical messengers produced by endocrine glands that take information around the body
What do target tissues have so only that tissue is affected by the hormone
Target tissues have : cells with complementary receptor proteins - for specific hormones, so only that tissue is affected
How do hormones travel
By the bloodstream
What do hormones control in reproduction
- the onset of puberty
- sperm production
- the menstrual cycle
What does the hypothalamus do at puberty
Secretes a releaser hormone whose target is the pituitary gland
How does the pituitary gland respond to the releaser hormone
By producing 2 hormones ( FSH + ICSH in males // FSH + LH in females)
What is FSH
A follicle stimulating hormone
What is ICSH
An interstitial cell-stimulating hormone
What is LH
A luteinising hormone
What do the release of hormones by the pituitary gland trigger
The onset of sperm production (males) and the menstrual cycle (females)
What does FSH do (males)
Promotes sperm production in the seminiferous tubules
What does ICSH do
Stimulates the interstitial cells to produce testosterone
What does testosterone do
- stimulates sperm production
- activates the seminal vesicles & prostate gland to produce secretions (fluids)
What is negative feedback control
The body had self-regulating mechanisms called negative feedback, allowing the body to correct changes. When a factor affecting the body’s internal environment deviates from its norm (set point) the body responds to correct the change)
Example of negative feedback control
As testosterone concentration builds up in bloodstream it reaches a level that inhibits FSH & ICSH secretion.
This leads to a decrease in testosterone concentration.
So, the pituitary gland releases FSH & ICSH again.
What does FSH (females)
- Stimulates the development & maturation of each follicle.
- Stimulates the ovary to secrete oestrogen by the follicle in the follicular phase
What does LH do
-Triggers ovulation
-Brings about development of the corpus luteum from the follicle, the corpus luteum then secretes progesterone
What are the ovarian hormones
Oestrogen & Progesterone
What does oestrogen stimulate
The proliferation (cell division) of the endometrium (inner layer of the uterus). This prepares the uterus for implantation of an embryo
What do high levels of oestrogen stimulate
The cells lining the cervix to secrete a watery mucus making it more easily penetrated by sperm
What do peak levels of oestrogen stimulate
-A surge in the secretion of LH which triggers ovulation.
-The production of LH by the pituitary.
What does the follicle do in the luteal phase
Develops into a corpus luteum & secretes progesterone
What does progesterone promote
The further development & vascularisation of the endometrium, preparing it for implantation if fertilisation occurs
Vascularisation meaning
Formation of blood vessels
