Renal Phys--> K+ Flashcards
what are the 2 purposes of K+?
Cell metabolism
Resting membrane potential
What are some truths about K+?
3000-4000 mmols of total storage
- 50-55mmol/Kg
- 95% intracellular
What are things that regulate K+?
- Insulin
- Catecholamines
- Aldosterone
What are some other factors that regulate this pump?
plasma K+
exercise
cell breakdown
chronic dz
How does insulin regulate K+?
Upregulates Na/k ATPase
- alleviates sharp rise in K+ after eating
- promotes skeletal and muscle uptake
How do Catecholamines regulate K+ and how?
B2 receptor stimulates Na/K ATPase
- No evidence that K+ releases Epi or NE
How does an increase in pH affect K+?
alters K+/H transporter.
- H is taken up by cells in exchange for K+
- Thus leads to serum hyperkalemia
How does tonicity affect K+?
during high glucose levels water leaves cell
- K + follows
What can be given to take someone out of Sine wave rhythm? What causes this?
Hyperkalemia is the cause
- Insulin
- Catecholamines
- Calcium
What is the Segmental control of K+ in the kidney?
proximal tubule- 50-65% absorption (mostly tight juctions)
TAL- 25% absorption
Principal cell- 10% leaving
What are some stimulators of K+ excretion?
- Increase Na delivery to distal tubule
- Increased flow rates
- Plasma levels of K+
- Aldosterone
What are the affects of aldosterone on the kidney?
Increase ENAC
increase ROMK
Increase Na/K ATPase expression
Where is the BigK channel found? Usually open or closed?
Apical membrane
usually closed
What affect does aldosterone have on ROMK?
Increases amount of ROMK embedded into apical membrane
When is aldosterone increased? Leads to what?
Increased K+
Increased flow
Leads to increased K+ excretion
