The body depends upon the mineral potassium's electrolytic properties to conduct nerve impulses, initiate muscle contractions, regulate the balance of acids and bases in the blood, facilitate biochemical processes and maintain proper fluid levels inside and outside cells. Electrolytes are ions -- compounds with a positive or negative electrical charge that are dissolved in fluids inside and outside of cells. Humans maintain proper levels of potassium in their body through the foods they eat or through potassium supplementation. Talk to your doctor before taking potassium supplements.
Role of Potassium In Biochemical Processes
Potassium is involved in several critical biochemical processes in the human body. Pyruvate kinase, an enzyme found in the liver, needs potassium present to assist it in the chemical production of glucose from compounds such as lactate and certain amino acids. Another enzyme, potassium-ATPase, requires the presence of potassium as it regulates the transport of substances into and out of cells through the cell wall.
Effect of Potassium on Other Electrolytes
Potassium is a positively charged electrolyte. Its presence or relative absence determines the way certain body systems handle other electrolytes such as sodium and calcium. Low potassium levels often coincide with relatively high amounts of calcium ion being excreted by the kidneys into the urine. High urinary calcium may cause kidney stones. Potassium ion binds with negatively-charged bicarbonate ions forming a buffer which maintains the body's acid-base balance. Low potassium may lead to acidic blood serum. Calcium is taken from bone tissue as the body tries to increase alkalinity. Too much loss of calcium from bone tissue may lead to osteoporosis.
Normally, the body contains much more potassium than sodium. High sodium and low potassium ion levels cause the kidneys to retain fluid, increasing blood pressure and putting more stress on the heart. Increasing intake of dietary potassium restores the electrolyte balance and lowers blood pressure.
Importance to Nervous System Function
The body uses potassium's electrolytic properties to conduct electrical signals along nerve and muscle cells. In the resting state, the interior of a nerve cell is negatively charged-more positively charged ions such as calcium, sodium and potassium are outside of the cell than inside. When the nerve cell receives appropriate stimulation, positive sodium ions will rush in and make the nerve cell's interior positively charged. When the positive charge inside the cell reaches a certain point, special gates open up and positively charged potassium ions leave the cell. This results in a restoration of the cell's normal negative, at-rest charge. There is a sequential movement of charges along the nerve cell body. These moving electrical charges are currents. In this way, electrical signals travel between nerve cells and from nerve cells to other parts of the body.
Potassium's Cardiovascular System Importance
Potassium's role in conducting electrical signals plays an important role in cardiovascular system function and health. Too much or too little potassium can cause irregular heart beats. There are two types of heart muscle cells: autorhythmic and contractile. Contractile heart muscle cells require stimulus from nerve cells before they contract. The nerve impulse stimulates the movement of sodium ions into the cell. Just as in nerve cells, potassium ions eventually exit and the cell becomes negatively charged. The resulting electrical current causes cardiac muscle contraction. Autorhythmic heart muscle cells work differently. Instead of an influx of sodium ions, a rush of positively charged calcium ions enter autorhythmic cells. The increase in calcium makes the cells' interior relatively positively charged. At a certain point, potassium ion exits the cell returning it to its resting, negative state. This process is automatic and self regulating; no nerve stimulation is necessary.
References
- Maryland School of Medicine; Potassium; Steven D. Ehrlich; 2009
- Linus Pauling Institute; Potassium; Victoria J. Drake; 2010
- Eastern Kentucky University: BIO 301 Human Physiology Cardiovascular system;
- University of Michigan Health System: Understanding Heart Failure-Answers to Common Questions; 2010
- Periodic Paralysis News Desk: Role of Potassium in Maintaining Health; Elson M. Haas, M.D.; 2000
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