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Figure

Acidosis results from an accumulation of acids or a loss of bases. Alkalosis results from a loss of acids or an accumulation of bases.

Shier-Butler-Lewis: I V. Absorption and I 21. Water, Electrolyte, and I I © The McGraw-Hill

Human Anatomy and Excretion Acid-Base Balance Companies, 2001

Physiology, Ninth Edition

pneumonia, or those that reduce surface area of the respiratory membrane, such as emphysema.

Any of these conditions can increase the level of carbonic acid and hydrogen ions in body fluids, lowering pH. Chemical buffers, such as hemoglobin, may resist this shift in pH. At the same time, increasing levels of carbon dioxide and hydrogen ions stimulate the respiratory center, increasing breathing rate and depth and thereby lowering carbon dioxide levels. Also, the kidneys may begin to excrete more hydrogen ions.

Eventually, thanks to these chemical and physiological buffers, the pH of the body fluids may return to normal. When this happens, the acidosis is said to be compensated.

The symptoms of respiratory acidosis result from depression of central nervous system function and include drowsiness, disorientation, and stupor. Evidence of respiratory insufficiency, such as labored breathing and cyanosis, is usually also evident. In uncompensated acidosis, the person may become comatose and die.

Metabolic acidosis is due to either accumulation of nonrespiratory acids or loss of bases (fig. 21F). Fac-

Decreased rate and depth of breathing

Obstruction of air passages

Accumulation of CO2

Respiratory acidosis tors that may lead to this condition include

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