In this article we will discuss about the Causes of Disturbances and Role of Acid-Base Balance.
Causes of Disturbances in Acid-base Balance:
A. Metabolic Acidosis:
1. It occurs in uncontrolled diabetes with ketosis.
2. It occurs in some cases of vomiting when the fluids lost are not acid.
3. It also occurs in renal disease, poisoning by an acid salt, excessive loss of intestinal fluids (as in diarrhea or colitis) and excessive losses of electrolytes.
4. Increased respiration is an important sign of uncompensated acidosis.
B. Respiratory Acidosis:
1. This occurs in any disease which impairs respiration such as pneumonia, congestive failure and asthma.
2. It is also found to occur in the depression of the respiratory center (as by morphine poisoning).
3. A poorly functioning respirator also causes this condition.
C. Metabolic Alkalosis:
1. Causes:
(a) By the ingestion of large quantities of alkali in the treatment of peptic ulcer.
(b) In the high intestinal obstruction (as in pyloric stenosis).
(c) After prolonged vomiting or after the excessive removal of gastric secretions containing hydrochloric acid.
(d) In Cushing’s disease and during corticotropin or cortisone administration.
2. Symptoms:
(a) Tetany is caused due to the decrease in ionized serum calcium.
(b) The respirations are slow and shallow.
(c) The urine is alkaline.
(d) Elevated blood bicarbonate.
(e) Deficiency of potassium.
D. Respiratory Alkalosis:
1. This is brought about by hyperventilation.
2. It may occur in patients in hepatic coma.
Role of the Kidney in Acid-Base Balance:
1. The non-volatile acids including lactic and pyruvic acids, hydrochloric acid, phosphoric acid and sulphuric acid are produced by metabolic processes. About 50-150 mEq of the inorganic acids are eliminated by the kidneys in 24 hours. These acids are partially buffered with cations, largely sodium. In the distal tubules of the kidney, some of the cations are reabsorbed and the pH of the urine falls.
2. Kidney can buffer acids and conserve fixed base in the production of ammonia from amino acids. The ammonia is utilized to neutralize acids when formed in excess.
3. In kidney disease, tubular reabsorption of sodium in exchange for hydrogen is poor and excessive retention of phosphates and sulphates. As a result, acidosis occurs.