HPA Axis II Flashcards
Name the hypothalamic stimulating hormone that causes the release of GnRH [1]
Kisspeptin
What do you need to remember about the structure of TSH, LH, FSH & HCG? [1]
Have same alpha subunit; different beta subunit
Explain oestrogen positive feedback of puberty cycle for LH / FSH
Gonad makes oestrogen, which has a positve effect on kisspeptin via GPR54 receptor
Kisspeptin neurones stimulate GnRH
GnRH stimulates gonadotrophs, which makes LH & FSH
Dsecribe the seperate regulation of LH and FSH via pulse frequency
Fast pulsing of LH causes high LH and low FSH
Low pulsing of LH: less LH and more FSH.
What happens if there is continious GnRH drive (as opposed to pulsatile drive) [1]
Which conditions would these be wanted in? [2]
What type of drugs would you use to achieve this? [1]
Causes receptor desensitisation
Used for when have prostate and breast cancer
Use GnRH analogues
How do you stimulate GnRH axis? [1]
Create pulsatile GnRH (from specific devices)
Describe path of GnRH neurone formation
What two phenotypes that occur if this process occurs innappropiately [2]
GnRH neurones develop in the olfactory epithelium.
During embryonic development GnRH neurones migrate through cribiform plate, guided by Kal protein & migrate to the hypothalamus
(neurones migrate with cells responsible for smell but go to olfactory bulb not the hypothalamus)
Causes a lack of smell and hypogonadism
Describe pathphysiology of Kallman syndrome [3]
Mutation in Kal protein [1]
During embryonic development these cells can’t enter brain: doesnt take neurones to hypothalamus / olfactory bulb
Cross stalk between two sides of the brain is innappropriate (so cant do movements with one hand indivdually)
How would you test for Kallman syndrome? [2]
Have shorter 4th metacarpal:
Test by putting pencil between small finger and middle finger metacarpal:
- Normal person the pencil wont touch if placed there
- Does in Kallman syndrome
Also: have greater span than height
Role of oxytocin? [4]
Giving birth, milk ejection
Social recognition
– “love hormone”
Pro-sociality
– For and maintain attachment bonds with others
Perceptual selectivity/social salience
– intranasal oxytocin increases gaze to the eye region
ADH MoA?
- Binds to collectng duct cell (binds V2 receptor)
- Causes increase in cAMP
- Activates PKA
- Causes increase in aquaporin synthesis
- Aquaporin molecules insert into luminal wall -> allow more water to be reabsorbed into the plasma.
Which disease is caused by an absence of ADH? [1]
How do you treat? [1]
(cranial / central) diabetes insipidus
Treat with desmopressin (ADH)
