HPA Axis Flashcards
Which hypothalamic nuclei is involved with particularly with the HPA axis? [1]
paraventricular nuclei
Which hypothalamic nuclei is involved with circadian rythym and sleep cycle? [1]
Supra-optic nuclei
Which hormones are produced by the AP? [6]
Which hormones are produced by the PP? [2]
Anterior Pituitary:
* Prolactin
* FSH & LH
* Growth Hormone
* TSH
* ACTH
Posterior Pituitary:
* Oxytocin
* ADH
Give an example of hormones for 1-5
1 & £ Hypothalamic cell that regulates another hypothalamic cell, which releases hypothalamic hormone down long portal vessel into the AP. E.g. 1: kisspeptin, 3:GnRH (causes release of LH & FSH
2 =. E.g GHRH. Made in hypothalamus and released directely into long portal vessel
4: ADH: releases contents in upper PP, via short portal vessels
5 =. ADH or oxytocin
Where does the pituitary gland sit? [1]
Sella turcica [1]
Label the different cranial nerves present in cavernous sinus
The anterior pituitary develops from which structure? [1]
Rathkes pouch
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
Give outline of GHRH & GH axis [2]
Which hormone inhibits release of Growth Hormone? [1]
Hypothalamus: GPR101 ligand creates GPR101: stimulates GHRH
Hypothalamus: GHRH stimulates production of GH
of Growth Hormone: works one every cell in the body. stimulates IGF-1
Somatostatin inhibits release of GH
Give regulator of prolactin release. How does this work?
Dopamine inhbits the release of prolactin, which used for milk glands and immune system
Fill in the blanks of thyroid axis
Damage to target organ causes what type of activity in HPA axis? [1]
What are features of this? [2]
Damage to primary organ causes primary underactivity:
- decreased target hormone
- increased pituitary hormone
OVERACTIVITY WOULD BE REVERSE OF THIS
Damage to AP / PP pituitary organ causes what type of activity in HPA axis? [1]
What are features of this? [2]
Damage to primary organ causes secondary underactivity:
- decreased target hormone
- decreased pituitary hormone
OVERACTIVITY WOULD BE REVERSE OF THIS
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 [1]
GSP oncogene:
Causes a mutant alpha subunit:
- cannot hydrolise GTP to GDP, which results with alpha subunit constantly activating adenylyl cyclase
Which sydnrome is created by a mosaic mutation in GNAS gene? [1]
How do they present? [3]
McCune-Albright syndrome
(Cannot be inherited)
Syndrome has classic traid of:
* polyostotic fibrous dysplasia of bone
* precocious puberty
* café-au-lait skin pigmentation
Who makes more GH:
women
men
GH regulation comes from which nucleus? [2]
Who makes more GH:
women
men
GH regulation comes either arcuate nucleus or infindibulum nucleus
Excess GH causes which pathology? [1]
What commonly causes this? [1]
Pituitary gigantism: pituitary tumour (GH secreting adenoma)
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
Gigantism and acromegaly due to Xq26 micropduplications and [] mutation
Gigantism and acromegaly due to Xq26 micropduplications and GPR101 mutation
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
Describe the pattern of cortisol release
Circadian rhythm (highest in morning)
Describe the difference between ACTH independent and ACH dependent Cushings syndrome
ACTH independent: too much cortisol, but not because ACTH is stimulating this increase in cortisol
ACTH dependent: cortisol increase due to increase in ACTH
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
