Sodium is used by the cells to regulate the amount of water they take in or expel. Sodium is also important for the communication between neurons and the function of muscles. Most of the body's sodium is found outside the cell. The concentration of sodium in the blood influences the blood pressure and, therefore, it must be tightly regulated to maintain adequate blood pressure.
Sodium Absorption
Sodium is absorbed in the small intestine. Its absorption facilitates the absorption of water and chloride in the intestines. It also assists in the absorption of glucose and amino acids. Sodium also facilitates the reabsorption of nutrients from the filtrate, or the solution that results from filtering blood in the kidneys.
Sodium and Blood Pressure Regulation
Sodium influences changes in the blood pressure by attracting water. When sodium is high in the blood, there is a change in the distribution of water in the body; high blood sodium causes water to leave the cells and enter the blood to dilute the sodium content, resulting in increased blood volume. The increase in blood volume leads to and elevation in blood pressure. Conversely, a decrease in blood sodium causes water to move from the blood vessel into the cells; this results in a decrease in blood pressure.
Excess aldosterone production
Aldosterone is release from the adrenal gland. It stimulates the kidneys to increase sodium reabsorption and the excretion of potassium. In a healthy person, aldosterone is produced as a result of hyponatremia, or low blood sodium, but in a person with a primary adrenal tumor, aldosterone is produced in excess, causing an increase in sodium in the blood. Blood pressure is increased by excess aldosterone production.
Dietary sodium
Sodium is found in meats, white bread, spaghetti sauce, whole milk, eggs and cheese pizza. Increased dietary intake of sodium results in increased absorption of sodium from the small intestine, which will have the net effect of increasing your blood pressure.
References
- Fooducate Blog:The Top 20 Sources of Sodium
- Harvard Partners International: Aldosteronism: Too much of a good thing
- "Harrison's Principles of Internal Medicine": Kasper M.D., et al., 2005
