What is the significance of sodium in biology?

In biology, sodium is a crucial nutrient which functions to regulate electrolyte and fluid balance, and blood pressure. Sodium transport in the proximal tube tubule permits the cotransport of solutes like glucose, amino acids, and phosphate. Sodium channels open and allow sodium to rush in when a nerve cell communicates with another. The flooding of sodium ions into the channel triggers the nerve cell to fire. This then causes a series of reactions as the signal is carried from nerve cell to nerve cell until it either travels to the brain or to a muscle for contraction. Sodium is the most abundant electrolyte in the body, which needs large amounts to function properly. Sodium enters the body via food and drinks and is excreted in urine and sweat. If sodium absorption and excretion are imbalanced, the total sodium levels in the body is affected, leading to problems such as hypothermia (not enough sodium) or hyperthermia (excessive amounts of sodium). Having a diet excess in sodium and low in potassium contributes to the development of hypertension.