The functions of sodium (Na+) and chloride (Cl-) – commonly known as common salt NaCL – are presented below: NaCl is found as Na+ and Cl- extracellularly, that is, outside the cells – in the blood plasma in contrast to potassium, which is accumulated intracellularly, that is, inside the cell. The different concentrations – inside and outside the cell – separated by the cell membrane, result in an electrochemical gradient known as the membrane potential. Energy in the form of ATP – adenosine triphosphate – is used to pump sodium (Na+) and chloride (Cl-) out of the cell and potassium into the cell. A harmonious balance of concentration inside and outside the cell is essential for the function of nerve signal transmission, muscle contraction and normal heart function.Common salt – sodium (Na+) and chloride (Cl-) – is of great importance for the extracellular body fluid (body water balance), of which blood plasma (blood fluid) is a component, and blood pressure. This is done by a comprehensive hormonal regulatory system – renin-angiotensin-aldosterone system – controlled by pressure receptors – which controls the excretion of sodium chloride by the kidneys, thus regulating blood volume and blood pressure: Drop in blood pressure leads to release of renin. Renin – an enzyme – converts the messenger angiotensinogen into angiotensin. This leads to vasoconstriction, i.e. contraction of the blood vessels and thus to an increase in blood pressure. Furthermore, angiotensin stimulates the release of aldosterone from the adrenal glands. The hormone aldosterone in turn influences kidney function, so that common salt is reduced and potassium is increasingly excreted. Another hormone, anti-diuretic hormone (ADH), is secreted by the pituitary gland as soon as blood volume or blood pressure drops. ADH then leads to decreased export of water in the kidney, that is, it has an antidiuretic effect.
