MET2 Revision 6 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
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
Label the different cranial nerves present in cavernous sinus
The anterior pituitary reqiures which transcription factors to develop? [1]
PIT1 [1]
What are developmental consequences of being deficient in PIT1? [2]
Hypothyroidism develops to create cretinism
Overall lacks TSH,GH and Prolactin
Label A-F
Roles of GHRH? [4]
- Stimulates GH release
- Stimulates GH synthesis
- Increases GH cell number
- Promotes GH cell clusters for coordinated responses
What type of receptor is GHRH receptor? [1]
Explain what happens when GHRH receptor is activated [2]
GPCR
Alpha subunit:
- cuts off a phosphate / hydrolises GTP to GDP which originally activated the alpha subunit (regulatory step: so that adenylyl cyclase isnt continually switched on
- activates adenylyl cyclase, which creates cAMP: second messenger to activte GH
Explain effect of gsp oncogene with regards to GHRH receptor and human pituitary tumours [1]
GSP oncogene:
Causes a mutant alpha subunit:
- cannot hydrolise GTP to GDP, which results with alpha subunit constantly activating adenylyl cyclase
Which syndrome is created by a mosaic mutation in GNAS gene? [1]
How do they present? [4]
McCune-Albright syndrome
(Cannot be inherited)
Syndrome has classic traid of:
* polyostotic fibrous dysplasia of bone
* precocious puberty
* café-au-lait skin pigmentation
* Acromegaly is seen in about 20% of patients with MA
How does GH bind to GH receptor?
Binding of GH to its receptor results in dimerization of the GHR: causes intra-cellular spinning of the receptor
Fill in the blanks for production of FSH & LH
A: Kisspeptin
B: GPR54
C: GnRH
Fill in the blanks for production of FSH & LH
A: Kisspeptin
B: GPR54
C: GnRH
What is the most common cause of ACTH-indepedent Cushing’s syndrome? [1]
Name two other causes
Exogenous glucocorticoid threapy (steroid therapy)
(e.g. long term inhaler use)
Can be due to adrenal hyperplasia or adrenal tumour
Thiazide diuretics work in which location of nephron? [1]
MoA of thiazide diuretics? [1]
Thiazide diuretics: work at DCT
MoA: Blocks Na/Cl transporter
Where do potassium sparing diuretics, such as spironolactone or eplerenonework in nephron? [1]
MoA? [1]
How do they ensure K+ reabsorption? [1]
Spironolactone and eplerenone work at CD
Both: aldosterone antagonists (Na/K transporter)
Because Na doesn’t get reabsorbed into blood, K doesn’t have to be excreted in exchange
Explain AEs of thiazide diuretics? [5]
On the levels of:
[Na, K, Ca2+, glucose, cholesterol]
Hypokalaemia: K+excretion is enhanced due to the increase in Na+delivered to the distal tubule / CD, where Na is reabsorped at expense of K+
Hypercalcaemia: Ca2+excretion is decreased via a poorly understood mechanism
Hyponatraemia (particularly in old people)
Hyperglycaemia: inhibits insulin secretion slightly
Hypercholesterolaemia: unknown mech
Explain two AEs of using loop diuretics? [3]
Hypokalemia: directly blocks K reabsorption through blockage of NaKCl2
Dehydration
Kidney stones: due to retained Ca in urine
Deafness