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Minerals of life – sodium and potassium

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IN continuation of ourdiscuss on minerals of life today, I will be presenting two minerals, sodium and potassium. I am writing about these two minerals because apart from their individual contributions to the wellbeing of man and their functions in the body, the two of them together play a very significant role in maintenance of osmotic balance between the cells and the interstitial fluid. Not only that, they are both involved in the electrochemical gradient that is created over the cell membrane that gives rise to the transmission of nerve impulses in neurons. 

Sodium

  This is an alkaline mineral that is predominantly found in the plasma and the extracellular fluid compartment. As an alkaline mineral, sodium helps to maintain the alkalinity of the tissues and fluid of the body.

Sodium is the main mineral involved in regulating the blood pressure through balancing the osmotic pressure and fluid volume in the body. This, it does through the renin-angiotensin-aldosterone system.

The renin-angiotensin-aldosterone system

   This is a system that incorporates certain hormones and enzymes in regulating the fluid volume in the body and by extension, the blood pressure. In response to reduced renal blood flow caused by dehydration for example and low concentration of sodium in the kidney, certain cells in the kidney convert prorenin in the plasma to renin. Renin in turn acts on angiotensinogen released from the liver to produce angiotensin 1. Angiotensin 1 is further converted to angiotensin 2 by the action of the enzyme, angiotensin converting enzyme produced in the lungs. 

    Angiotensin 2 has two functions: Firstly, it causes the constriction of the arterioles and capillaries in the body. Secondly, it causes the release of aldosterone from the cortex of the adrenal glands. Aldosterone acts on the tubules of the kidneys to cause them to increase reabsorption of sodium and water into the blood. This helps to increase the fluid volume in the body. Increased fluid volume and sodium concentration block the production of renin and puts a check on the renin-angiotensin-aldosterone system.

    The Na+/P+-ATPase pump is responsible for pumping 3 ions of sodium from inside the cell to the outside and 2 ions of potassium into the cell. The energy for this pump to function in pumping the sodium ions out of the cells is supplied by ATP. This creates an electrochemical gradient over the cell membrane which becomes converted to an electrical impulse.

Sources of sodium

   The main source of sodium is from table salt, otherwise called NaCl (sodium chloride). This sodium chloride and by extension sodium, can be found in drinking water, in veggies such as celery and beets and in milk. Other sources are MSG (Monosodium Glutamate) and processed meats, ham and bacon for example, canned vegetables and fast foods.

Potassium

   Also an alkaline mineral, potassium, is the main mineral inside the cells. It is necessary for the functions of all living cells. As I have already mentioned, it plays a significant role in the osmotic balance between the cells and interstitial fluid through the Na+/K+-ATPase pump. It maintains fluid and electrolyte balance in the body. Potassium is also involved in the transmission of impulse in the neurones (nerves and the brain). Furthermore, researchers have discovered that potassium protects blood vessels from free radical damage and also prevents plaque formation on the vessels.

Sources of potassium

   Rich sources of potassium include sweet potatoes, tomato sauces/puree, runner (white) beans, chocolate, dried milk, dried apricot, parsley, pistachios, almonds, bananas, avocados and soybeans. Other sources are beet leaves, yogurt, prunes, orange juice, carrot juice and fish (tuna, halibut and cod).

Hypokalaemia

   Deficiency of potassium in the body is known as hypokalaemia. Likely causes of hypokalaemia are excessive urinating, diarrhoea, excessive vomiting and sweating. Other causes are Crohn’s disease and ulcerative colitis.


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