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Renal Final > K, Ca, Mg, PO4 Endocrinology > Flashcards

K, Ca, Mg, PO4 Endocrinology Flashcards

1
Q

Which of the following has the highest potassium distribution within its cells?

A. Liver
B. Bone
C. Muscle
D. Kidneys

A

C. Muscle

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2
Q

Potassium plays an important role in cell volume maintenance. What would the effects be of:

  • Net loss of K+
  • Net gain of K+
A

Net loss of K+ = cell shrinkage

Net gain of K+ = cell swelling

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3
Q

Potassium plays an important role in intracellular pH regulation. What would the effects be of:

  • Low plasma [K+]
  • High plasma [K+]
A

Low plasma K+ = cell acidosis

High plasma K+ = cell alkalosis

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4
Q

What effect does lack of potassium have on protein synthesis?

A

Reduced protein synthesis and stunted growth

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5
Q

What effect do changes in the transmembrane [K+] ratio have on resting cell membrane potential?

A

Reduced [K]in:[K]out = membrane depolarization

Increased [K]in:[K]out = membrane hyperpolarization

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6
Q

What effect do changes in the transmembrane [K+] ratio have on neuromuscular activity?

A

Low plasma [K] = muscle weakness, muscle paralysis, intestinal distension, respiratory failure

High plasma [K] = initially increased muscle excitability, later muscle weakness (paralysis)

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7
Q

What effect do changes in the transmembrane [K+] ratio have on cardiac activity?

A

Low plasma [K] = prolonged repolarization; slowed conduction; abnormal pacemaker activity, leading to tachycardia

High plasma [K] = enhanced repolarization; slowed conduction, leading to bradyarrhythmias and cardiac arrest

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8
Q

What effect do changes in the transmembrane [K+] ratio have on vascular resistance?

A

Low plasma [K]: vasoconstriction

High plasma [K]: vasodilation

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9
Q

99% of calcium is stored in ________, and 90% is excreted in _____

A

Bone; feces

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10
Q

Which of the following is important in the formation of bone from the body calcium pool?

A. Calcitonin
B. PTH
C. Calcitriol
D. Both PTH and calcitriol

A

A. Calcitonin

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11
Q

What is the effect of hypocalcemia on neuromuscular excitability?

A

INCREASES in neuromuscular excitability (hypocalcemic tetany/spacsticity)

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12
Q

What is the effect of hypercalcemia on neuromuscular excitability?

A

DEPRESSES neuromuscular excitability (threshold shifts away from resting membrane potential)

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13
Q

Primary hyperparathyroidism and malignancy are related to which of the following?

A. Low serum calcium
B. Low serum potassium
C. Elevated serum calcium
D. Elevated serum potassium

A

C. Elevated serum calcium

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14
Q

Hypoparathyroidism, renal disease, and vitamin deficiency are associated with which of the following?

A. Low serum calcium
B. Low serum potassium
C. Elevated serum calcium
D. Elevated serum potassium

A

A. Low serum calcium

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15
Q

Where is the majority of phosphate stored in the body?

A

Bone (85%)

The rest is in cells (14%) and serum (1%)

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16
Q

Fine-tuning of circulating phosphate levels is mostly under the control of renal excretion. Reabsorption depends on the _______ ________

A

Transport maximum (Tm)

17
Q

What are the 4 main known regulators of phosphate metabolism?

A

Dietary

Calcitriol

PTH

Renal tubular reabsorption of phosphorus

18
Q

What percent of total magnesium is considered free (unbound) serum Mg2+?

A

69%

19
Q

Depletion of which of the following is associated with migraines, depression, epilepsy, SIDS, arrhythmia, preeclampsia, and muscle cramps?

A. Calcium
B. Phosphate
C. Magnesium
D. Potassium

A

C. Magnesium

20
Q

What effect does PTH have on serum calcium and serum phosphate levels?

A

Increases serum Ca

Decreases serum Pi

21
Q

What effect does calcitonin have on PTH, Ca and Pi concentrations?

A

Calcitonin opposes PTH

Decreases serum Pi and Ca concentrations

22
Q

What effect does calcitriol have on serum Ca and Pi levels?

A

Increases serum Ca and Pi levels

23
Q

Action of PTH on bone

A

Increases osteoclastic resorption

24
Q

Action of PTH on intestine

A

Increases Ca/Pi absorption indirectly via Vit D (calcitriol) production

25
Q

Action of PTH on the kidney

A

Increased reabsorption of Ca primarily in DCT

Decreased reabsorption of Pi in PCT

Decreased activity of Na/H antiporter

Decreased bicarb reabsorption

26
Q

Excess PTH can cause what conditions?

A

Hypercalcemia
Hypophosphatemia
Hypercholermic metabolic acidosis

27
Q

T/F: Calcitonin is inhibited by hypercalcemia

A

False: calcitonin is stimulated by hypercalcemia

28
Q

Action of calcitonin on bone

A

Inhibits osteoclastic-mediated bone resorption

29
Q

Action of calcitonin on kidney

A

Promotes phosphate excretion

Promotes calcium excretion

30
Q

Pharmacologic doses of calcitonin are used in what types of conditions?

A

Osteoporosis

Paget’s disease

Hypercalcemia

31
Q

Action of calcitriol on bone

A

Promotes osteoid mineralization

Osteoclastic mediated bone resorption

32
Q

Action of calcitriol in the intestine

A

Increases calcium absorption (30% dietary calcium is absorbed)

Increases phosphorus absorption

33
Q

Action of calcitriol on kidney

A

Increased phosphate reabsorption

Increased Ca reabsorption

34
Q

Stimulus for secretion and action on kidneys of:

PTH

A

Stimulus for secretion: decreased plasma [Ca]

Action on kidneys:
Decreased Pi reabsorption (PT)
Increased Ca reabsorption (DT)

35
Q

Stimulus for secretion and action on kidneys of:

ADH

A

Stimulus for secretion:

  • increased plasma osmolarity
  • decreased blood volume

Action on kidneys:
-increased H2O permeability (late DT and CCD principal cells)

36
Q

Stimulus for secretion and action on kidneys of:

Aldosterone

A

Stimulus for secretion:

  • decreased blood volume (via RAAS)
  • increased plasma [K]

Action on kidneys:

  • increased Na reabsorbtion (ENaC in DT principal cells)
  • increased K secretion (DT principal cells)
  • increased H secretion (DT alpha-IC cells)
37
Q

Stimulus for secretion and action on kidneys of:

ANP

A

Stimulus for secretion:
-increased atrial pressure

Action on kidneys:

  • increased GFR
  • Decreased Na reabsorption
38
Q

Stimulus for secretion and action on kidneys of:

Angiotensin II

A

Stimulus for secretion:
-decreased blood volume (via renin)

Actions on kidneys:
-Na/H exchange and HCO3 reabsorption (PT)

Renal Final (10 decks)

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