Chapter 29: Renal Regulation Of K, Ca, PO, Mg

Question 0

Ions controlled by an overflow mechanism

Answer 0

Potassium

Phosphate

Question 1

ECF Potassium concentration

Answer 1

4.2mEq/L

Question 2

Hormones that increase potassium uptake into cells

Answer 2

Insulin
Aldosterone
Epinephrine

Question 3

Acid-base abnormality causing a decrease potassium concentration in the ECF or Hypokalemia

Answer 3

Alkalosis

Question 4

Effect of increased H ion concentration on K

Answer 4

Reduces activity of Na-K ATPase pump –> Increases K on ECF

Question 5

Potassium abnormality caused by Cellular lysis, strenuous exercise and intake of B-adrenergic blockers

Answer 5

Hyperkalemia

Question 6

How does increased ECF osmolarity increase K in the ECF

Answer 6

Osmosis out of cells –> cellular dehydration –> increased K concentration in cells –> K diffusion out of the cells

Question 7

Most important sites for regulating K excretion

Answer 7

Principal cells of the late distal tubules and cortical collecting tubules

Question 8

Intercalated cells of the late distal tubules and cortical collecting tubules contain what transporter which aids in potassium reabsorption

Answer 8

H-K ATPase in the luminal membrane

Question 9

3 mechanisms that raises K secretion during increased ECF K concentration

Answer 9

• stimulation of Na-K ATPase pump
• diffusion of K from increased gradient
• stimulation of aldosterone secretion

Question 10

Effect of Addison’s disease in K concentration in the blood

Answer 10

Hyperkalemia

Addison’s dse –> dec aldosterone –> dec K secretion –> hyperkalemia

Question 11

Chronic Acidosis leads to what potassium abnormality

Answer 11

Hypokalemia

Chronic acidosis decreases NaCl and Water reabsorption in the proximal tubules –> increasing distal volume delivery –> overrides inhibitory effect oh inc H on Na-K ATPase pump –> K secretion

Question 12

ECF Ca ion concentration

Answer 12

2.4 mEq/L

Question 13

50% of Ca is in what form, which has biologic activity at cell membranes

Answer 13

Ionized form

Question 14

Effect of alkalosis in the binding of Ca and plasma proteins

Answer 14

More Ca is bound to plasma proteins in alkalosis –> prone to hypocalcemic tetany

Question 15

Large share of Ca excretion occurs in

Answer 15

Feces

Question 16

Percentage of Ca deposition in the bone

Answer 16

99%

Question 17

Effect of PTH

Answer 17

Increases Bone resorption –> increase Ca levels in ECF

Question 18

Calcium is filtered, reabsorbed and secreted in the kidneys. True or False

Answer 18

False. Only filtered and reabsorbed; not secreted

Question 19

Most of calcium reabsorption occurs through which transport pathway in the proximal tubule

Answer 19

Paracellular pathway

Question 20

Transport mechanism for Ca as it exits the cell across the basolateral membrane from the proximal tubule

Answer 20

Primary active transport (Ca-ATPase)

Secondary active transport (Na-Ca counter transport)

Question 21

50% of Ca reabsorption in the thick ascending limb occurs through the paracellular route by passive diffusion and 50% through the transcellular pathway which is stimulated by what hormone?

Answer 21

PTH

Question 22

PTH, Vitamin D and Calcitonin stimulates ca reabsorption in which tubular segments?

Answer 22

Thick ascending limb

Distal tubule

Question 23

Reabsorption of Ca in which segment parallels Na and water reabsorption and is independent of PTH

Answer 23

Proximal tubule

Question 24

Effect of acidosis on Ca reabsorption

Answer 24

Increased

Question 25

Threshold of phosphate in the ECF

Answer 25

0.8 mM/L

Question 26

Proximal tubule reabsorbs 75-80% of filtered Phosphate occurring through which pathway and transporter in luminal membrane?

Answer 26

Transcellular pathway through the Na-PO4 con-transporter

Question 27

Effect of PTH on Phosphate and Ca reabsorption

Answer 27

Decreased PO4 reabsorption | Increased Ca reabsorption

Question 28

Ions stored in the bones

Answer 28

Ca PO4 Mg

Question 29

Total plasma Mg concentration

Answer 29

1.8 mEq/L

Question 30

Free ionized concentration of Mg

Answer 30

0.8 meq/L

Question 31

In disturbances of kidney function which are not too severe, Na balance may be achieved mainly by systemic adjustments. True / False

Answer 31

False. Mainly by intrarenal adjustments with minimal changes in ECF volume

Question 32

Severe perturbations of the kidney exhausts intrarenal compensations so that systemic adjustments must be invoked. True / False

Answer 32

True

Question 33

If kidneys become greatly vasodilated and GFR increases, NaCl delivery to the tubules leads to two intrarenal compensations. What are these?

Answer 33

- glomerulotubular balance | - macula densa feedback

Question 34

Refers to the effect of increased BP to raise urinary volume excretion

Answer 34

Pressure diuresis

Question 35

Effect of increased Na excretion that occurs with increased BP

Answer 35

Pressure natriuresis

Question 36

Chronic increases in BP suppresses the release of which hormone, which enhances the effectiveness of pressure natriuresis

Answer 36

Renin

Question 37

Trace the basic renal-body fluid feedback mechanism

Answer 37

Increase fluid intake ➡️ fluid accumulation in ECF ➡️ inc blood volume ➡️ inc mean circulatory filling pressure ➡️ inc venous return ➡️ inc cardiac output ➡️ inc arterial pressure ➡️ pressure diuresis to inc urine output

Question 38

Blood volume and ECF volume are controlled simultaneously. True / False

Answer 38

True. Ingested fluid initially goes into the blood but rapidly becomes distributed between interstitial spaces and plasma

Question 39

Neither a decrease nor an increase in circulating angiotensin II has a large effect on ECF volume or blood volume as long as HF or KF does not occur. True or False

Answer 39

True

Question 40

Excess ADH secretion causes only small increases in ECF volume and large increases in Na concentration. True or False

Answer 40

False. Only small increases in ECF due to pressure diuresis and large decreases in Na concentration because of ECF dilution

Question 41

Action of ANP

Answer 41

Increased salt and water excretion d/t increase GFR and decrease Na reabsorption by the collecting ducts

Question 42

Conditions that cause large increases in blood volume and ECF volume

Answer 42

- heart diseases | - increased capacity for circulation (pregnancy, varicosities)

Question 43

Conditions that cause large increases in ECF volume but with normal blood volume

Answer 43

Nephrotic syndrome | Liver cirrhosis