Difference between revisions of "Hypothalamus Differences in the Male and Female - Anatomy & Physiology"
Jump to navigation
Jump to search
Fiorecastro (talk | contribs) |
|||
(16 intermediate revisions by 4 users not shown) | |||
Line 1: | Line 1: | ||
+ | {{toplink | ||
+ | |backcolour =EED2EE | ||
+ | |linkpage =Reproductive System - Anatomy & Physiology | ||
+ | |linktext =Reproductive System | ||
+ | |maplink = Reproductive System (Content Map) - Anatomy & Physiology | ||
+ | |pagetype =Anatomy | ||
+ | |sublink1=Reproductive System - Anatomy & Physiology#Puberty | ||
+ | |subtext1=PUBERTY | ||
+ | }} | ||
+ | <br> | ||
+ | |||
== Introduction == | == Introduction == | ||
− | The [[Hypothalamus_- | + | * The [[Hypothalamus_-_Anatomy_%26_Physiology|hypothalamus]] is inherently female. |
+ | * [[Endocrine_System_-_Testes_-_Anatomy_%26_Physiology|Testosterone]] 'defeminizes' the brain during embryogenesis and eliminates the GnRH surge centre in males. | ||
+ | * The female foetus has no testes to produce [[Endocrine_System_-_Testes_-_Anatomy_%26_Physiology|testosterone]], thus developes a [[Hypothalamus_-_Anatomy_%26_Physiology|hypothalamic]] GnRH surge centre. | ||
== Defeminizing the Hypothalamus in the Male == | == Defeminizing the Hypothalamus in the Male == | ||
− | Testosterone crosses the [[ | + | * Testosterone crosses the [[Blood_Brain_Barrier_%28BBB%29|blood-brain barrier]] and is converted into oestradiol. |
+ | * In the brain, oestradiol 'defeminizes' the [[Hypothalamus_-_Anatomy_%26_Physiology|hypothalamus]]. | ||
+ | * Surge centre function is minimized. | ||
+ | * Complete 'defeminization' of the brain requires postnatal exposure to androgens. | ||
+ | * Continued exposure to androgens is required to render the surge centre inoperative. | ||
+ | * As a result, LH does not surge, it maintains a relatively consistent episodic pattern of secretion every day. | ||
+ | ** Episodes occur every 2-6 hours in the postpubertal male. | ||
+ | * Steady, pulsatile GnRH and LH release results in a steady, pulsatile release of [[Endocrine_System_-_Testes_-_Anatomy_%26_Physiology|testosterone]]. | ||
== The Female Hypothalamus == | == The Female Hypothalamus == | ||
− | Foetal ovaries produce oestradiol, but this does NOT defeminize the [[Hypothalamus_- | + | * Foetal ovaries produce oestradiol, but this does NOT defeminize the [[Hypothalamus_-_Anatomy_%26_Physiology|Hypothalamus]]. |
− | + | * A protein called alpha-fetoprotein binds oestradiol to prevent it from crossing the [[Blood_Brain_Barrier_%28BBB%29|blood brain barrier]], therefore oestradiol cannot effect the [[Hypothalamus_-_Anatomy_%26_Physiology|Hypothalamus]]. | |
− | Alpha fetoprotein functions as | + | * Alpha-fetoprotein is synthesized firstly by the embryonic yolk sac and then by the foetal liver. |
− | + | * Alpha fetoprotein functions as: | |
− | + | ** Foetal blood osmotic regulator | |
− | + | ** Carrier of fatty acids | |
− | + | * As GnRH surges, LH and Oestradiol surge about every 20 days in the female. | |
− | + | ** Surge frequency varies between species, dependent on the length of their [[Female_Reproductive_Tract_-Oestrous_Cycle_-_Anatomy_%26_Physiology|oestrous cycles]]. | |
− | + | * Between surges, there are low amplitude LH pulses. |
Revision as of 13:55, 4 September 2008
|
Introduction
- The hypothalamus is inherently female.
- Testosterone 'defeminizes' the brain during embryogenesis and eliminates the GnRH surge centre in males.
- The female foetus has no testes to produce testosterone, thus developes a hypothalamic GnRH surge centre.
Defeminizing the Hypothalamus in the Male
- Testosterone crosses the blood-brain barrier and is converted into oestradiol.
- In the brain, oestradiol 'defeminizes' the hypothalamus.
- Surge centre function is minimized.
- Complete 'defeminization' of the brain requires postnatal exposure to androgens.
- Continued exposure to androgens is required to render the surge centre inoperative.
- As a result, LH does not surge, it maintains a relatively consistent episodic pattern of secretion every day.
- Episodes occur every 2-6 hours in the postpubertal male.
- Steady, pulsatile GnRH and LH release results in a steady, pulsatile release of testosterone.
The Female Hypothalamus
- Foetal ovaries produce oestradiol, but this does NOT defeminize the Hypothalamus.
- A protein called alpha-fetoprotein binds oestradiol to prevent it from crossing the blood brain barrier, therefore oestradiol cannot effect the Hypothalamus.
- Alpha-fetoprotein is synthesized firstly by the embryonic yolk sac and then by the foetal liver.
- Alpha fetoprotein functions as:
- Foetal blood osmotic regulator
- Carrier of fatty acids
- As GnRH surges, LH and Oestradiol surge about every 20 days in the female.
- Surge frequency varies between species, dependent on the length of their oestrous cycles.
- Between surges, there are low amplitude LH pulses.