🧪Endocrinology🧪 - Disorders of Vasopressin Flashcards
What is the pathway of AVP release?
Supraoptic hypothalamic nuclei -> pituitary stalk -> posterior pituitary
Originates in magnocellular neurones
What is the other name for arginine vasopressin (AVP)?
Anti-diuretic hormone (ADH)
What is diuresis?
The production of urine
What is the main physiological action of AVP?
Stimulation of water reabsorption in the renal collecting duct, via V2 receptors
Concentrates urine, increases blood volume
What are 2 physiological effects of AVP, other than stimulating water reabsorption?
Acts as a vasoconstrictor, via the V1 receptor
Stimulates ACTH release from anterior pituitary (much smaller impact than CRH obviously)
Describe the chemical cascade after AVP binds to its target
AVP binds to g-protein coupled v2 receptor
Causes adenylate cyclase to form cAMP
cAMP then forms** protein kinase A**
Protein kinase A interacts with vesicles containing aquaporin-2
Aquaporin-2 channels insert into the apical membrane, leading to water movement into the cell
What receptors are responsible for the release of AVP?
Osmoreceptors
What triggers osmoreceptors?
Increase in plasma osmolality is sensed
Where are osmoreceptors located?
The hypothalamus
How do osmoreceptors regulate AVP release?
What is the normal physiological response to water deprivation?
What are the 2 types of conditions relating to the inefficacy of AVP?
Arginine vasopressin deficiency (AVP-D)
Arginine vasopressin resistance (AVP-R)
Outline AVP-D
Cranial (central) diabetes insipidus
Problem with the hypothalamus and/or posterior pituitary
Inability to properly produce AVP
Outline AVP-R
Nephrogenic diabetes insipidus
AVP production is fine
Kidney (collecting duct) unable to respond
Is insensitivity to AVP
How does AVP deficiency/resistance present?