Potassium Regulation Flashcards
What is the dietary intake of K per day ?
100 mg
Where is the majority of K located ?
ICV
What is the external K balance ?
Regulation in total K balance through alterations in intake ( dietary ) and excretion ( renal GI ect. )
What is the internal balance of K ?
Distribution of K between the ICV and the ECV
What is the normal renal excretion of K ?
Normal GI excretion
90 - 95 mEq / Day
GI excretion is 5-10 mEq per day
What is the total body K ?
What tissues contain the most K ?
Total Body K is 3300 mEq
Muscle (2500 mEq)
Liver (250)
RBC (250)
Bone (200)
What are the major sites of K secretion ?
Cortical collecting duct. It is dependent on the concentration of aldosterone .
Principal cells in CCT and outer medullary CT
Where is K reabsorbed ?
The proximal convuluted tubule and TALH. also can be reabsorbed in the inner medullary collecting duct.
What are the effects of aldosterone in the principal cells of the CT ?
It diffuses into the nucleus where it causes upregulation of …
- Epithelial Na channel
- ROMK K+ channel
- NaKATPase ion pump.
Whare are the factors that effect K secretion ?
- Concentration gradient of K across the basolateral membrane (Serum K conc)
- Electrical activity across luminal mem- dependent on the conc. of Na.
- K+ permeability- Aldosterone concentration
What happens to the lumen of the CT when a greater amount of Na is reabsorbed ?
It will create electronegativity which will promote greater K secretion. Greater Na delivery to the distal tubule will promote Na uptake and K secretion.
