T3 L10: Fluid balance Flashcards
What type of vasopressin receptor causes contraction of blood vessels?
V1
Where are V2 receptors found?
In the basal membrane of principle cells in the collecting duct
What type of Aquaporin is inserted into the collecting duct as a result of ADH activity?
AQP2
What do maximal ADH levels do to urine output?
Minimise urine output
What 2 factors cause ADH release?
Plasma osmolality and effective circulating volume (ECV)
Which receptors detect changes in [Na+]?
Osmoreceptors in the hypothalamus
Which receptors detect changes in pressure?
Baroreceptors
Where is ADH released from?
The posterior lobe of the pituitary gland
How does urea help to increase ECV?
It helps to reabsorb more water in the loop of Henle
What is ECV?
Effective circulating volume. The volume of water in the body
How do osmoreceptors help to decrease plasma osmolality?
They stimulate thirst and release of ADH so more water is reabsorbed in the kidneys and we increase the water intake
How do baroreceptors help to increase ECV?
They stimulate the release of ADH, RAAS, ANP, and sympathetic NS
Where are the 3 low pressure volume receptors in the body?
Large systemic veins, cardiac atria, and pulmonary vasculature
Where are the 3 high pressure volume receptors in the body?
Carotid sinus, aortic arch, and the renal afferent arteriole
What ion regulates ECV regulation?
[Na+]
Where is decreased renal perfusion detected in the kideny?
In the afferent arteriole (the renal baroreceptor)
Which cells in the kidney detect [Na+]?
Macula densa cells (renal Na+ sensor)
What are the 5 effects of Angiotensin II?
- Increases sympathetic activity
- Increases tubular Na+, Cl-, and H2O reabsorption and K+ excretion
- Stimulates aldosterone secretion
- triggers arteriolar vascular contraction
- Stimulates ADH secretion
What are all the actions of Angiotensin II and aldosterone designed to increase?
ECV
What does Aldosterone stimulate?
Na+ reabsorption in the distal tubule and collecting duct
How does the RAAS react to a low ECV?
Low ECV is detected by renal baroreceptors and renal Na_ sensors. The RAAS is activated so Angiotensin II and Aldosterone work to reduce Na+ excretion and increase Na+ reabsorption in the kidneys
How does the ANS react to low ECV?
Low ECV is detected by peripheral baroreceptors which signal to the hypothalamus. The ANS is activated causing direct effects on renal haemodynamic and the RAAS is activated. This causes reduced Na+ excretion and increased Na+ reabsorption
How does ADH react to low EVC?
Low ECV is detected by peripheral baroreceptors which signal to the hypothalamus. ADH is released into circulation which causes increased reabsorption of water
True or false, low ECV is the same as high plasma osmolality?
True
What is ANP and what is its function?
Atrial natriuretic peptide and its designed to lower ECV by promoting natriuresis (Na+ excretion)
Which molecule inhibits actions of renin and opposes effects fo Angiotensin II?
ANP
Where is ANP produced and stored?
In atrial monocytes
Which stimulates ANP release?
An increase in ECV causes atrial stretch which triggers release
