24.2 Electrolyte Balance

Question 1

electrolyte balance

Answer 1

a state in which the amount of electrolytes absorbed by the small intestine balances the amount lost from the body

Question 2

physiological importance of electrolytes

Answer 2

1) participation in metabolism, 2) determination of electrical potential across cell membranes, 3) effect on osmolarity of body fluids and body’s water content and distribution

Question 3

major cations of electrolytes

Answer 3

sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), hydrogen (H+)

Question 4

major anions of electrolytes

Answer 4

chloride (Cl-), bicarbonate (HCO3-), phosphates (Pi)

Question 5

aldosterone

Answer 5

salt-retaining hormone whose secretion from the adrenal cortex is directly stimulated by hyponatremia and hyperkalemia and indirectly stimulated by hypotension

Question 6

primary effects of aldosterone

Answer 6

less NaCl, more potassium, and lower pH in urine

Question 7

hypernatremia

Answer 7

an excess of sodium ions in the blood (plasma sodium concentration > 145 mEq/L); can result from administration of IV saline; causes water retention, hypertension, and edema

Question 8

hyponatremia

Answer 8

a deficiency of sodium ions in the blood (plasma sodium concentration < 130 mEq/L); usually the result of excess body water rather than excess sodium excretion; usually corrected by excretion of excess water but can produce hypotonic hydration if not

Question 9

hyperkalemia

Answer 9

an excess of potassium ions in the blood (> 5.5 mEq/L); results from ruptured cells, outdated blood transfusion, hyposecretion, renal failure, acidosis; can cause cardiac arrest

Question 10

hypokalemia

Answer 10

a deficiency of potassium ions in the blood (< 3.5 mEq/L); results from heavy sweating, chronic vomiting or diarrhea, excessive use of laxatives, aldosterone hypersecretion, or alkalosis; causes muscle weakness, loss of muscle tone, depressed reflexes, and irregular electric activity of the heart

Question 11

calsequestrin

Answer 11

a protein that binds stored Ca2+ and keeps it chemically unreactive in cells

Question 12

hypercalcemia

Answer 12

an excess of calcium ions in the blood (> 5.8 mEq/L); can result from alkalosis, hyperparathyroidism, or hypothyroidism; reduces the sodium permeability of plasma membranes and inhibits the depolarization of nerve and muscle cells; causes muscular weakness, depressed reflexes, and cardiac arrhythmia

Question 13

hypocalcemia

Answer 13

a deficiency of calcium ions in the blood (> 4.5 mEq/L); can result from Vitamin D deficiency, diarrhea, pregnancy, lactation, acidosis, hypoparathyroidism, hyperthyroidism; causes nervous and muscular systems to be overexcitable; can cause tetany

Question 14

hypermagnesemia

Answer 14

an excess of magnesium ions in the blood (> 2.0 mEq/L); rare except in renal insufficiency; causes lethargy, muscle weakness, and weak reflexes, respiratory depression or failure, hypotension, and cardiac arrest

Question 15

hypomagnesia

Answer 15

a deficiency of magnesium ions in the blood (< 1.5 mEq/L); can result from intestinal malabsorption, vomiting, diarrhea, or renal disease; results in hyperirritability of the nervous and muscular systems, muscle tremors, spasms, or tetanus, hypertension, tachycardia, and ventricular arrythmia

Question 16

hyperchloremia

Answer 16

an excess of chloride ions in the blood (> 105 mEq/L); usually the result of dietary excess or administration of IV saline

Question 17

hypochloremia

Answer 17

a deficiency of chloride ions in the blood (<95 mEq/L); usually a side effect of hyponatremia but sometimes results from hyperkalemia or acidosis