Final answer:
Hypernatremia is an elevation of plasma Na+ concentration above normal, caused by water loss or hormonal imbalances involving ADH and aldosterone. It indicates an abnormal increase in blood sodium levels.
Step-by-step explanation:
Hypernatremia is a plasma Na+ (sodium ion) concentration above normal. This condition is indicative of an abnormal increase in blood sodium levels, which might be caused by several factors, including a significant water loss from the blood, leading to the hemoconcentration of all blood constituents. Hemoconcentration refers to the concentration of cells and solids in the blood, resulting in a decrease in plasma volume. This can cause the sodium concentration to appear higher when measured.
Hormonal imbalances, particularly those involving antidiuretic hormone (ADH) and aldosterone, can also contribute to hypernatremia. ADH's primary role is to regulate water balance in the body by controlling the amount of water reabsorbed from the nephrons in the kidneys. Aldosterone affects the balance of sodium and potassium in the blood. An increase in aldosterone can lead to the retention of sodium, which can elevate sodium levels in the plasma.
In reference to body fluid compartments, sodium ions (Na+) are at the highest concentration in the extracellular fluid (ECF). The sodium-potassium pumps found in cell membranes actively work to maintain this balance, using ATP to pump sodium out of the cell and potassium into the cell, ensuring the body fluids remain neutral in charge with balanced cations and anions.