Electrolyte balance Flashcards
(21 cards)
Which cells release renin?
Granular cells of the afferent arteriole
What are the 3 main triggers of renin release?
Low afferent arteriole pressure
Activation of sympathetic nerves that supply the JGA
Low NaCl in distal tubule
What effect does the RAAS system have on blood pressure?
Increases BP
What are the 4 key effects of angiotensin II?
Vasoconstriction
Increased sodium & water reabsorption in kidneys
Aldosterone release
ADH release & increased thirst
Which receptor does angiotensin II bind to in the nephron?
AT1
How does the binding of angiotensin II to AT1 receptors in the nephron lead to increased sodium reabsorption?
It increases the activity of sodium transporters such as:
- Na+/K+ATPase on the basolateral membrane
- NHE (sodium-hydrogen exchanger) on the apical membrane
Aldosterone
- works on which cells?
- binds to which receptor?
- increases numbers of which transporter?
Principal cells
Intracellular mineralocorticoid receptor
ENaC
Atrial natriuretic peptide (ANP) is released in response to what?
Increased BP / volume
What effect does ANP have on the afferent arteriole, and therefore GFR?
Dilates afferent arteriole - increasing GFR
Atrial natriuretic peptide (ANP) has what effect on sodium reabsorption?
Decreases sodium reabsorption
Which 4 factors shift potassium into cells / decrease extracellular potassium?
Insulin
Aldosterone
B-adrenergic stimulation
Alkalosis
Which 6 factors shift potassium out of cells / increase extracellular potassium?
Insulin deficiency / diabetes
Aldosterone deficiency (Addison’s disease)
B-adrenergic blockade
Acidosis
Strenuous exercise
Increased extracellular osmolarity
Which mechanism in the nephron causes the greatest variation in potassium excretion?
Secretion in the late distal tubule / cortical collecting tubule
Which 3 factors determine the rate of K+ secretion?
Activity of Na+/K+ATPase
K+ gradient between blood, principal cells, and lumen
Permeability of luminal membrane to K+
Which 4 factors regulate potassium secretion?
Plasma potassium concentration
Aldosterone
Tubular flow rate
H+ concentration
In what way does aldosterone affect the rate of potassium excretion?
Increases potassium excretion
In what way does increased H+ affect the rate of potassium excretion?
Decreases potassium excretion
By which 2 mechanisms does aldosterone increase potassium excretion?
Increases Na+/K+ ATPase activity
Increases permeability of luminal membrane to K+
By which 2 mechanisms does increased tubular flow rate increase potassium excretion?
Increase K+ gradient from principal cells to lumen
Increases permeability of luminal membrane to K+
By which mechanism does increased H+ decrease potassium excretion?
Decreases Na+/K+ATPase activity
Which medication can be given to stabilise the myocardium in hyperkalaemia?
Calcium gluconate
