Physio: Kidney Solute Processing: Potassium, Calcium, Magnesium

Question 1

Majority of the total body K+ is freely dissolved in the ___________

Answer 1

Cytosol of tissue cells

Question 2

____________ constitutes the major osmotic component of the intracellular fluid

Answer 2

K+

Question 3

Hypokalemia

Answer 3

When K+ (plasma) < 3.5 mEq/L

Question 4

Hyperkalemia

Answer 4

When K+ (plasma) > 5 mEq/L

Question 5

Significant hypokalemia causes sustained _________________

Answer 5

Depolarization

Whereas, hyperkalemia may hyper or hypo-polarize cells

Both lead to muscle and cardiac disturbances

Question 6

Healthy K+ balance….

Answer 6

Excrete K+ in response to diet and withholding excretion when K+ is depleted

Question 7

Moment to moment K+ regulation….

Answer 7

Muscle buffers K+(ECF) by taking up or releasing K+

This protects the ECF from large swings in K+ concentration

Question 8

What hormones regulate K+?

Answer 8

insulin and epinephrine

Question 9

Potassium is freely filtered into bowman’s space….

Answer 9

65% of the filtered load is reabsorbed
Via the paracellular route
Driven by water reabsorption which concentrates K+

Flux is unregulated and varies with how much Na+/H20 is reabsorbed

Question 10

Henle’s loop reabsorbs approximately ________% of the filtered loads of K+

Answer 10

25%

The ascending limbs of Henle (both thin and thick) reabsorb K+

Question 11

Bartter Syndrome (Type 3)

Answer 11

Mutations directly or indirectly involving the NKCC2

Symptomology similar to people on loop diuretics

Question 12

What is the determinant of excitability of nerve and muscle, especially the heart?

Answer 12

K+