Term
|
Definition
|
|
Term
| almost all K+ filtered is: |
|
Definition
| reabsorbed by proximal tubules |
|
|
Term
| What cells secrete K+ into the tubular fluid/urine? |
|
Definition
|
|
Term
| What increases K+ secretion? |
|
Definition
| increased tubular flow, increased NA delivery, aldosterone |
|
|
Term
| What are the mechanisms by which aldosterone increases K+ secretion? |
|
Definition
| stim. Na+/K+ ATPase, inserts NA channels of luminal membrane, opens passive K+ exit channels in luminal membrane |
|
|
Term
| What does the Maxi-K channel do? |
|
Definition
| Secrete K+ without stimulation from aldosterone |
|
|
Term
| What factors increase transcellular K+ movement into cells (facilitating hypokalemia)? |
|
Definition
| B stimulation, Insulin, rapid genesis of cell cytoplasm (ie re-feeding), alkalemia |
|
|
Term
| How does acidosis affect transcellular K+ movement? |
|
Definition
| It favors K+ exit from cells (Hyperkalemia) |
|
|
Term
|
Definition
|
|
Term
| How do you treat hyperkalemia? |
|
Definition
| IV Ca if urgent (to stabilize cardiac cell membrane), IV glucose & inuslin to push K+ into cells, B stim drug, kayexelate, dialysis |
|
|
Term
| what factors promote K+ movement out of cells (hyperkalemia) |
|
Definition
| acidosis, cell destruction and hemolysis, B blockade, hyperglycemia |
|
|
Term
| How does tubular flow affect K+ secretion? |
|
Definition
| increased tubular flow increases K+ secretion into urine |
|
|
Term
| How does Na delivery to principal cells affect K+ secretion into urine? |
|
Definition
| increased Na delivery increases K+ secretion into urine (Na reabsorbed leaves - charge in lumen which draws K+ in) |
|
|
Term
| What does aldosterone do? |
|
Definition
stimulates Na/K ATPase on basolateral membrane (^K cells into lumen)
opens/inserts Na channels on luminal membrane (Na enter, lumen becomes negative, K+ enters lumen)
opens/favors passive K+ exit channels in luminal membrane |
|
|
Term
| What causes K+ to move into cells (hypokalemia)? |
|
Definition
| B stim, theophylline, caffeine, refeeding syndrome |
|
|
Term
| How do you treat urgent hyperkalemia? |
|
Definition
| IV Ca to stabilize cardiac cell membrane |
|
|
Term
| How can you treat hyperkalemia? |
|
Definition
IV gluc & insulin (pushes K+ into cells)
B stim
Kayexelate |
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|
