Lec 4 - PPG + vasopressin Flashcards
what does vasopressin doo
pormote reabsorption of water back into circulation, so less is lost in urine
where does vasopressin act in the nephron
- Distal convulated tubule
- collecting duct
how does adh increase water reabsorp
stim synthesis of aquaporins
and their insertion into membrane of kidney tubule cells
what do aquaporins do
transport solute free water through tubular cells of kidney back into blood
what would a decrease in plasma osmolality be
DILUTION of the blood
(which in turn means increased osmolality of the urine - yelow pee)
what receptors does vasopressin bind to on kidney tubule cells
V2 receptors
(a Gs GPCR)
what pathway does vasopressin stimulate
adenylate cyclase -> cAMP -> PKA activated
which aquaporin specifically is synthesised when vasopressin present
AQP-2
gets inserted into APICAL membrane
which aquaporins are constituently present in basolateral membrane
AQP 3 and 4
what is increased osmolality in the blood detected by
hypothalamic osmoreceptors
which stim secretion of vasopressin from hypothalamic neurons
how are baroreceptors involved in vasopressin secretion
barorec in aortic arch, left atrium and carotid sinus detect drop in blood vol
- stim adh release
negative feedback in adh release
a decrease in plasma osmolality
or
an increase in plasma volume
negatively feeds back and reduces adh release
what external pressures can increase adh secretion
basically anything bad
- angiotensin
- pain
- anxiety
- nausea
- vomiting
- haemorrhage
- drugs e.g. nicotin, morphine
what external things can decrease adh secretion
ethyl alcohol
caffiene
how can adh affet vascular system
- not much in humans, but other species
- high conc of adh causes constric of arterioles
- increases arterial pressure
how is thirst linked to adh secretion
- osmotic threshold for adh secretion is much lower
- before thirst appears, adh will have already been released and in full effect
what is some possible overlap of adh and oxytocin, interms of secondary effects of adh
- memory formation/learning
- anti fever and pain relief properties
- social = fatherly behaviour (this is wehre it possibly overlaps)
2 types of diabetes insipidus
- hypothalamic (central) DI
- nephrogenic DI
what could hypothalamic DI be caused by
- head trauma
- infections
- tumours
that involve the hypothalamus
what could nephrogenic DI be caused by
- renal disease
- mutated vasopressin receptor gene
- mutated AQP-2 gene
how could DI be treated
- exogenous vasopressin (only for hypothalamic)
- nephrogenic only treated with enough water intake, otherwise nothing else
symptom of DI
excessive urine production
