acidosis

(ăs'ĭ-dō'sĭs)
n.
An abnormal increase in the acidity of the body's fluids, caused either by accumulation of acids or by depletion of bicarbonates.

acidotic ac'i·dot'ic (-dŏt'ĭk) adj.

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An increase in the acidity of blood plasma to below the normal range of pH 7.3-7.45, resulting from a loss of the buffering capacity of the plasma, alteration in the excretion of carbon dioxide, excessive loss of base from the body, or metabolic overproduction of acids.

The human body functions best when blood and tissue fluids are neither too alkaline nor too acidic. An abnormally high acidity of blood and tissue fluids is called acidosis. It results in chemical reactions taking place less efficiently and can impair muscular contractions which may lead to fatigue.

There are two main types of acidosis: metabolic acidosis and respiratory acidosis. Metabolic acidosis may be caused by loss of bases (chemicals which readily accept hydrogen ions and decrease acidity), ingestion of highly acidic foods, or the production of excessive amounts of acid in the body. Respiratory acidosis results from a failure to exhale carbon dioxide from the lungs as quickly as it forms in respiring tissues. Carbon dioxide accumulates in the blood and tissues where it forms carbonic acids. Heavy or severe exercise may also cause temporary acidosis by producing large amounts of both lactic acid and carbon dioxide. Persistent acidosis is rare and usually associated with disease.

We usually respond to acidosis by breathing very heavily in order to flush out excess carbon dioxide from the body and eliminate excess acids (a process called compensatory hyperventilation). Some athletes use sodium hydrogen carbonate (sodium bicarbonate or baking soda) as a performance enhancer in the belief that it decreases acidity and reduces the risk of acidosis. Research evidence suggests that ingestion of 300 mg of bicarbonate per kilogram of body weight can enhance the performance of all-out, maximal aerobic activities lasting from 1 to 7 minutes.

An abnormally high acidity of the blood and tissue fluids. Acidosis can reduce the efficiency of metabolic reactions, interfere with muscle actions, and may lead to fatigue. There are two main types of acidosis: metabolic acidosis and respiratory acidosis. Metabolic acidosis may be caused by loss of bases, ingestion of highly acidic foods, or the production of excessive amounts of acids in the body (e.g. during severe exercise when large amounts of both lactic acid and carbon dioxide are produced). Respiratory acidosis results from a failure to exhale carbon dioxide from the lungs as quickly as it forms in respiring tissues. Carbon dioxide accumulates in the blood and tissues, where it forms carbonic acids. Sufferers of acidosis usually breathe very heavily in order to flush out excess carbon dioxide from the body and eliminate excess acids (a process called compensatory hyperventilation). Some athletes use sodium hydrogen carbonate (baking soda) as a performance enhancer in the expectation that it decreases acidity and reduces the risk of acidosis. Compare alkalosis.

a clinical condition in which excess acid or a base deficit tends to cause increased hydrogen-ion concentration (i.e. lowered pH) in the blood.

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A pathological condition resulting from accumulation of acid or depletion of the alkaline reserve (bicarbonate content) in the blood and body tissues, and characterized by increase in hydrogen ion concentration (decrease in pH).
The optimal acid–base balance is maintained by chemical buffers, biological activities of the cells, and effective functioning of the lungs and kidneys. The opposite of acidosis is alkalosis.
It is rare that acidosis occurs in the absence of some underlying disease process. The more obvious signs of severe acidosis are muscle twitching, involuntary movement, cardiac arrhythmias, disorientation and coma.

• compensated a. — a condition in which the compensatory mechanisms have returned the pH toward normal.
• diabetic a. — a metabolic acidosis produced by accumulation of ketones in uncontrolled diabetes mellitus.
• hypercapnic a. — respiratory acidosis.
• iatrogenic a. — may result from administration of drugs, such as urinary acidifiers, or anesthetic agents which depress respiration.
• lactic a. — the accumulation of lactate in the rumen in ruminants and the stomach of horses, and hence in the blood, as a result of overfeeding with readily fermentable carbohydrate. See also carbohydrate engorgement.
• metabolic a. — acidosis resulting from accumulation in the blood of keto acids (derived from fat metabolism) at the expense of bicarbonate, thus diminishing the body's ability to neutralize acids. This type of acidosis can occur when there is an acid gain, as in diabetic ketoacidosis, lactic acidosis, poisoning and failure of the renal tubules to reabsorb bicarbonate. It can also result from bicarbonate loss due to diarrhea or a gastrointestinal fistula.
• mixed alkalosis and a. — characterized by low serum chloride, normal or slightly elevated plasma bicarbonate and a very high anion gap.
• organic a. — accumulation of organic anions occurs in uremia, diabetic acidosis and lactic acidosis, and ingestion of salicylates, ethylene glycol or methanol.
• renal tubular a. — renal tubular malfunction leads to faulty resorption of bicarbonate or excretion of acid and the production of alkaline urine; types I (distal tubular acidosis) and II (proximal tubular acidosis) are identified.
• respiratory a. — acidosis resulting from ventilatory impairment and subsequent retention of carbon dioxide.
• ruminal a. — acidosis caused by an altered metabolic state, usually lactic acidosis, in the rumen.
• starvation a. — a metabolic acidosis due to accumulation of ketones following a severe caloric deficit.
• uncompensated a. — a condition in which the compensatory mechanisms have not been applied sufficiently to return the pH of the blood to normal.
• uremic a. — see metabolic acidosis (above).

(as′idō′sis)
n

A pathologic disturbance of the acid-base balance of the body characterized by an excess of acid or inadequate base. Causes include acid ingestion, increased acid production such as that seen in diabetes or starvation, or loss of base through the kidneys or intestine.

For a list of words related to acidosis, see:

• Afflictions and Conditions - acidosis: excess acidity in blood, due to kidney malfunction or diabetes
• Physiology - acidosis: abnormal state of reduced alkalinity of blood and tissues

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