Lecture 20: Renal Regulation of Ion Concentrations

Question 1

What happens when there is higher concentrations of extracellular potassium?

Answer 1

cardiac arrest or fibrillation

Question 2

What is the normal intracellular concentration of potassium ion?

Answer 2

140 mEQ/L

Question 3

What are the major factors responsible for potassium excretion?

Answer 3

direct influence on distal renal tubules and collecting ducts via increase in extracellular potassium ion concentrations

effects of aldosterone secretion on potassium excretion: increase in extracellular potassium stimulates increase in aldosterone secretion

Question 4

Where does reabsorption occur?

Answer 4

proximal tubule

ascending limb of henle

Question 5

Where does secretion occur?

Answer 5

late tubule

collecting duct

Question 6

mechanisms of potassium secretion and sodium reabsorption and secretion by ____

Answer 6

principal cells

Question 7

high sodium diet leads to little change in _____

Answer 7

potassium excretion

Question 8

What is acidosis?

Answer 8

less calcium is bound to the plasma proteins

Question 9

What is alkalosis?

Answer 9

More calcium is bound to the plasma protein

Question 10

Where is almost all of calcium stored?

Answer 10

bone

Question 11

What are PTH effects?

Answer 11

stimulates bone reabsorption
stimulates activation of vitamin D
indirectly increases tubular calcium reabsorption

Question 12

_____ percent of filtered calcium is reabsorbed

Answer 12

99

Question 13

Reabsorption in loop of henle is restricted to the _____

Answer 13

thick ascending limb

Question 14

calcium reabsorption in distal tubule is almost entirely _____ transport

Answer 14

active

Question 15

What decreases calcium excretion?

Answer 15

increase levels of PTH
increase levels of concentration of phosphate
increase metabolic alkalosis

Question 16

What is phosphate excretion controlled by?

Answer 16

overflow mechanism

Question 17

PTH promotes bone excretion, which ____ phosphate in extracellular fluid

Answer 17

increases

Question 18

If PTH decrease transport maximum for phosphate by renal tubules, then there is a greater _______ of phosphate in urine

Answer 18

loss

Question 19

What does insulin do?

Answer 19

stimulates potassium uptake by cells

Question 20

What is hypokalemia?

Answer 20

excess secretion of aldosterone (Conn’s syndrome)

Question 21

What is hyperkalemia?

Answer 21

deficiency in aldosterone secretion (Addison’s disease)

Question 22

What does aldosterone do?

Answer 22

increases potassium uptake by cells
stimulates active reabsorption of Na+ by principal cells via Na+K+ATPase
increases permeability of luminal membrane for K+
increases extracellular K+

Question 23

What do catecholamines do?

Answer 23

Beta adrenergic stimulation

Question 24

Metabolic acidosis ______ extracellular K+

Answer 24

increases

Question 25

Metabolic alkalosis _____ extracellular K+

Answer 25

decreases

Question 26

What is the normal rate of potassium filtration?

Answer 26

180 L/day

Question 27

Rate is the rate of potassium reabsorption in the proximal tubule and loop of henle

Answer 27

65% proximal tubule

25-30% loop of henle

Question 28

Where are principal cells found?

Answer 28

late distal tubule and cortical collecting tubules

Question 29

What factors stimulate K+ secretion?

Answer 29

increase in:
extraceullar fluid K+ concentration
aldosterone
tubular flow rate

Question 30

What do intercalated cells do?

Answer 30

reabsorb K+ during K+ depletion