isotónicoisotónica

Isotónico refers to a solution that has the same osmotic pressure as another solution. In biology and medicine, this commonly refers to a solution that has the same solute concentration as blood plasma or other bodily fluids. This property is crucial for maintaining cell integrity and function. When cells are placed in an isotonic solution, there is no net movement of water across the cell membrane. This is because the concentration of solutes is equal inside and outside the cell, resulting in equal osmotic pressures.

The most common example of an isotonic solution in a medical context is normal saline, which is a 0.9% sodium chloride solution. This solution is used intravenously to rehydrate patients, to dilute medications, and as a vehicle for drug administration. Other isotonic solutions exist, such as Ringer's lactate, which contains electrolytes in proportions similar to those found in blood.

In sports and exercise physiology, the term isotonic is also used to describe a beverage designed to replenish fluids and electrolytes lost through sweat. These "isotonic drinks" aim to match the electrolyte concentration of the body's fluids, allowing for rapid absorption and rehydration. This contrasts with hypotonic solutions, which have a lower solute concentration and can cause cells to swell, and hypertonic solutions, which have a higher solute concentration and can cause cells to shrink due to water loss. The principle of matching osmotic pressure is key to the effectiveness and safety of these solutions.