Pierce - Regulation Of K+

Question 1

What effect does INSULIN have on the EXTRARENAL regulation of Plasma K+?

Answer 1

Stimulates Na+/K+ Exchanger —> K+ INTO cells and Na+ LEAVE cells

Insulin & Glucose TOGETHER treat HYPERkalemia.

Question 2

In Type I Diabetes Mellitus, what effect does the lack of insulin have on K+?

Answer 2

DECREASED K+ uptake into cells because Na+/K+ ATPase NOT STIMULATED.

Hyperkalemia can present with UNTREATED Type 1 Diabetes Mellitus

Question 3

What effect does ALDOSTERONE have on the EXTRARENAL regulation of Plasma K+?

Answer 3

INCREASE K+ Secretion into Intestinal Fluids and Saliva.

Enhances acid excretion via production of systemic alkalosis

Question 4

What effect does EPINEPHRINE have on the EXTRARENAL regulation of Plasma K+?

Answer 4

DECREASES Serum K+ through uptake into cells of extrarenal tissues

Question 5

What effect does INSULIN have on K+ distribution across the cell?

Answer 5

Inside Cell - INCREASED
Outside Cell - DECREASED

Stimulates Na+/K+ ATPase

Question 6

What effect do Beta Catecholamines have on K+ distribution across the cell?

Answer 6

Inside Cell - INCREASED
Outside Cell - DECREASED

Stimulates Na+/K+ ATPase by upregulating cAMP

Question 7

What effect do Alpha Catecholamines have on K+ distribution across the cell?

Answer 7

Inside Cell - DECREASED
Outside Cell - INCREASED

Inhibits Na+/K+ by downregulating cAMP

Question 8

What effect does ACIDOSIS have on the K+ distribution across the cell?

Answer 8

Inside Cell - DECREASED
Outside Cell - INCREASED

Inhibition of Na+/K+ ATPase

H+ will move into cell in exchange for K+ outside cell

Question 9

What effect does ALKALOSIS have on K+ distribution across the cell?

Answer 9

Inside Cell - INCREASED
Outside Cell - DECREASED

Move H+ outside cell to restore pH balance, so K+ moved into cell to maintain electroneutrality.

Question 10

What effect does CELL DAMAGE have on K+ distribution across the cell?

Answer 10

Inside Cell - DECREASED
Outside Cell - INCREASED

Cell contents (High K+ inside) spill outside

Question 11

What effect does HYPEROSMOLALITY have on K+ distribution across the cell?

Answer 11

Inside Cell - K+ DECREASES
Outside Cell - K+ INCREASES

Water leaves cell —> ICF K+ concentration increases —> K+ moves down concentration gradient

Question 12

What effect does STRENUOUS EXERCISE have on distribution of K+ in the cell?

Answer 12

Enhanced K+ Cell Efflux

Notes: K+ efflux assists by being a vasodilator metabolite for exercising muscle —> dilates muscle and increase blood flow.

Question 13

What is the equation for Filtered Load of K+?

Answer 13

Filtered Load = (GFR)(Plasma Concentration)(% Filterability)

Question 14

What is the mechanism for K+ REABSORPTION in the Proximal Tubule?

Answer 14

1. Na+ REABSORBED with HCO3- in Early PCT
2. Cl- left behind; Neg. TEPD Buildup
3. Cl- repelled and REABSORBED
4. NaCl REABSORPTION drags H20 REABSORPTION (Solvent Drag)
5. Pos. TEPD Buildup; K+ repelled and REABSORBED paracellulary

Question 15

Which circumstances would stimulate K+ SECRETION in the Distal Tubule and Cortical Collecting Duct?

Answer 15

High K+ Diet
Hyperaldosteronism
Alkalosis
Thiazide Diuretics
Loop Diuretics
Luminal Anions

Question 16

Which circumstances would stimulate K+ REABSORPTION in the Distal Tubule and Cortical Collecting Duct?

Answer 16

Low K+ Diet
Hypoaldosteronism
Acidosis
K+ Sparing Diuretics

Question 17

Which cells of the Distal Tubule and Collecting Duct SECRETE K+? What are the 3 most important factors that stimulate K+ SECRETION?

Answer 17

Principal Cells and Beta-Intercalated Cells

Most Important Factors:

• Increased ECF [K+]
• Aldosterone
• Increased Tubular Flow Rate

Question 18

Which cells of the Distal Tubule and Collecting Duct REABSORB K+? What are the 3 most important factors that stimulate K+ REABSORPTION?

Answer 18

Alpha-Intercalated Cells

Most Important Factors:

• K+ Deficiency/Low K+ Diet/ Hypokalemia
• K+ loss through SEVERE diarrhea