K+ Flashcards
major mechanism of transport in the proximal tubule
Na-K-ATPase pump in the basolateral membrane
a-catecholamines
- effect on K+
decrease cell uptake (hyperkalemia)
how does aldosterone enhance acid secretion of K+
production of systemic alkalosis
principal cells
- reabsorb
- secrete
- Na+, H2O
- K+
during volume expansion,
what increases distal K+ secretion and what decreases it
3 most important factors that stimulate potassium secretion
- increased ECF K+
- aldosterone
- increased tubular flow rate
alkalosis
- effect on K+
increase cell uptake (hypokalemia)
effect on anion delivery on K+
increases K+ secretion
- acts as osmotic diuretic and increases fluid flow rate
cell damage
- effect on K+
- mechanism
decrease cell uptake (hyperkalemia)
release of intracellular contents
strenuous exercise
- effect on K+
- mechanism
increase cell efflux of K+ via alpha catecholamines
during volume contraction,
what increases distal K+ secretion and what decreases it
effect of glucocorticoids on K+
increases K+ secretion via binding of mineralcorticoid receptor, increasing GFR, and increasing fluid flow rate
role of epinephrine on K+
- decreases uptake into cells extrarenally
- increases K+ secretion
beta-intercalated cells
- reabsorb
- secrete
- H+, Cl-
- K+, HCO3-
after K+ is secreted into cortical collecting duct, what part of the duct is it reabsorbed at
outer medullary and inner medullary
alpha-intercalated cells
- reabsorb
- secrete
- K+, HCO2-
- H+
2 most important factors that stimulate potassium reabsorption
- K+ deficiency
- K+ loss through severe diarrhea
during high water intake,
what increases distal K+ secretion and what decreases it
ADH does both
in acidosis,
what increases distal K+ secretion and what decreases it
when is K+ reabsorbed in the late DT and cortical CD
only if you have low K+ levels
b-catecholamines
- effect on K+
- mechanism
increase cell uptake
NaKATPase w/ cAMP
insulin
- effect on K+
- mechanism
increase cell uptake
NaKATPase
where is the H+/K+ exhanger located for beta intercalated cells and alpha intercalated cells
beta: basolateral membrane
alpha: apical membrane
hyperosmolality
- effect on K+
- mechanism
increase cell efflux of K+
contraction of ICF and increased intracellular K+
after K+ is reabsorped from the OMCD and IMCD, where is it secreted into
late proximal tubule and descending LoH
what are the two membrane transporters on prinicipal cells that secrete K+
BK (big potassium channel)
ROMK (renal outer medullary potassium channel)
acidosis
- effect on K+
- mechanism
decrease cell uptake (hyperkalemia)
donnan effect; inhibition of NaKATPase
filtered load equation
FL = GFR x Plasma concentration x %filterability
