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Essay on Potassium:- 1. Physiological Functions of Potassium 2. Sources of Potassium 3. Distribution 4. Daily Requirement 5. Blood Potassium 6. Absorption 7. Excretion 8. Disease State.
Contents:
- Essay on the Physiological Functions of Potassium
- Essay on the Sources of Potassium
- Essay on the Distribution of Potassium
- Essay on the Daily Requirement of Potassium
- Essay on the Blood Potassium
- Essay on the Absorption of Potassium
- Essay on the Excretion of Potassium
- Essay on the Disease State of Potassium
Essay # 1. Physiological Functions of Potassium:
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a. Potassium is largely present in the intracellular fluid and it is also present in small amounts in the extracellular fluid because it influences cardiac muscle activity.
b. It plays an important role in the regulation of acid-base balance in the cell.
c. It maintains osmotic pressure.
d. It functions in water retention.
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e. It is essential for protein biosynthesis by ribosomes.
f. The glycolytic enzyme pyruvate kinase requires K+ for maximal activity.
Essay # 2. Sources of Potassium:
The high content of potassium is found in chicken, beef liver, bananas, the juices of oranges, pineapples, jams, winter squash and potatoes, etc.
Essay # 3. Distribution of Potassium:
Essay # 4. Daily Requirement of Potassium:
The normal intake of potassium in food is about 4 gm. It is so widely distributed in food that its deficiency is rare except under pathological conditions.
Essay # 5. Blood Potassium:
The normal level of potassium in serum is 3.5 to 4.5 mEq/L. In man, erythrocytes contain large amounts of potassium. Therefore, care must be taken to avoid hemolysis for the determination of serum potassium. The serum potassium decreases during increased carbohydrate utilization following administration of glucose or insulin. Aldosterone decreases serum potassium level.
Essay # 6. Absorption of Potassium:
Normally, potassium is practically completely absorbed from the gastrointestinal tract and less than 10 per cent of potassium is eliminated in the feces. In subjects with diarrhea, large amounts of potassium are lost in the feces.
Essay # 7. Excretion of Potassium:
Potassium is normally eliminated almost entirely in the urine and a small amount in the feces. Aldosterone exerts an influence on potassium excretion. In the presence of normal kidney function, potassium is very promptly and efficiently removed from the blood. Normally, 25-100 mEq of potassium is excreted in urine in 24 hours.
Essay # 8. Disease State of Potassium:
a. Potassium is not only filtered by the kidney but is also secreted by the renal tubules. The excretion of potassium is greatly influenced by changes in acid-base balance and also by the activity of the adrenal cortex. The capacity of the kidney to excrete potassium is very great and, therefore, hyperkalemia does not occur even after the ingestion of potassium if the kidney function is unimpaired.
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Potassium should not be given intravenously unless circulatory collapse and dehydration are corrected.
b. Hyperkalemia occurs in patients in the following conditions:
(i) Renal failure,
(ii) Severe dehydration,
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(iii) Addison’s disease due to decreased excretion of potassium by the kidney,
(iv) Intravenous administration of excessive amounts of potassium salts,
(v) Shock.
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The symptoms of hyperkalemia are cardiac and central nervous system depression. The heart signs include bradycardia and low heart sounds followed by peripheral vascular collapse leading to cardiac arrest.
The other symptoms are mental confusion, numbness, weakness of respiratory muscles and flaccid paralysis of the extremities. The symptoms are corrected by administration of deoxycorticosterone which helps the excretion of potassium.
c. Prolonged hypokalemia causes injury to myocardium and kidneys. Potassium deficits occur in chronic wasting diseases with malnutrition, prolonged negative nitrogen balance, gastrointestinal losses and in metabolic alkalosis.
The clinical conditions exhibiting hypokalemia are:
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(i) Prolonged diarrhea and vomiting with the loss of digestive juices.
(ii) Intravenous administration of potassium- free fluid to replace digestive juices lost by prolonged vomiting.
(iii) Over activity of adrenal cortex (Cashing’s syndrome) which causes increased excretion of potassium in urine.
(iv) Prolonged use of diuretics.
(v) Heart failure treatment with digitalis.
(vi) Diabetic coma treatment with insulin.
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(vii) In familial periodic paralysis, a rare disease, potassium is withdrawn from extracellular fluid and retained in the cells.
The symptoms of hypokalemia are muscular weakness, irritability, paralysis, tachycardia and dilatation of the heart with gallop rhythm and changes in the electrocardiogram (ECG).
