Chapter 27: Fluid, Electrolytes and Acid-Base Balance

Approximate amount of total body fluid in a male.

60%

Amount of body fluid that is extracellular fluid.

1/3

Hormone increases excretion of sodium into urine and thus increases water loss.

Atrial natriuretic peptide

Sources of water gain.

Ingested liquid, food, and metabolic water.

Approximate amount of total body fluid in a female.

55%

Amount of body fluid that is intracellular.

2/3

Hormone reduces water loss in urine by increasing sodium reabsorption and therefore water follows.

Aldosterone

Sources of water loss

Urine, sweat, exhalation of water, and through GI tract.

Antidiuretic hormone

Hormone reduces water loss in urine by causing collecting ducts to become more permeable to water.

Hypothalamus

Location of the thirst center.

Amount of extracellular fluid that is interstitial.

80%

Amount of extracellular fluid that is blood plasma.

20%

Sodium

Most abundant cation in the extracellular fluid - blood levels controlled by aldosterone and atrial natriuretic peptide.

Potassium

Most abundant cation in the intracellular fluid - blood levels controlled by aldosterone.

Calcium

Most abundant mineral in the entire human body - blood levels controlled by parathyroid hormone and calcitonin.

Chloride

Most abundant anion in the extracellular fluid.

Respiratory acidosis

Increased pCO2 (above 45 mmHg) and decreased pH (below 7.35). Causes include COPD, Pulmonary edema, and asthma.

Respiratory alkalosis

Decreased pCO2 (below 35 mmHg) and increased pH (above 7.45). Causes include hyperventilation due to stress or pain.

Metabolic acidosis

Decreased bicarbonate (HCO3-) and decreased pH (below 7.35). Persistent diarrhea, excessive alcohol consumption, and kidney failure.

Metabolic alkalosis

Increased bicarbonate (HCO3-) and increased pH (above 7.45). Causes include persistent vomiting and excessive intake of antacids.