IB Sports, exercise and health science A.2.1.1 Water and Electrolyte Balance: Mechanisms and Regulation Key Definitions

A hormone that regulates sodium and potassium levels in the body, influencing water retention and blood pressure.

A hormone that increases water reabsorption in the kidneys to prevent dehydration.

The dynamic process of losing body water. It is the action that produces a state of hypohydration.

Substances that increase urine production, leading to fluid loss (e.g., caffeine, alcohol, certain medications).

Electrolytes are ions that carry an electric charge in body fluids. They are essential for nerve transmission, muscle contractions, and maintaining fluid balance.

A state of normal or appropriate body water content, characterised by the absence of both hyperhydration and hypohydration.

The fluid contained outside cells. It makes up about one-third of total body water, with around 80% as interstitial fluid between cells and 20% as blood plasma. It has a high concentration of sodium ions.

Homeostasis is the maintenance of a stable internal environment within an organism, ensuring optimal conditions for cellular processes.

A state of excess body water content, above the normal range.

A state of insufficient or suboptimal body water content, produced by the process of dehydration.

The fluid contained inside cells. It makes up about two-thirds of total body water and has a high concentration of potassium ions.

Negative feedback is a homeostatic mechanism in which a change in a physiological condition triggers a response that counteracts the initial change, maintaining balance.

Osmolarity is the concentration of solutes (such as ions and glucose) in a solution, measured in osmoles per liter (Osm/L). It is crucial for maintaining fluid balance and cell function in the body.