sisekeskkonda

Sisekeskkond, physiology term, refers to the internal milieu surrounding the cells of an organism. It comprises the extracellular fluids, including plasma and interstitial fluid, and is distinct from the intracellular milieu. The composition of the internal environment is tightly regulated in terms of water content, electrolyte balance, acid-base status, temperature, and nutrient supply to ensure proper cell function.

Maintaining a stable sisekeskkond is known as homeostasis. The body uses negative feedback loops to keep variables within narrow ranges. Receptors monitor conditions (thermoreceptors, osmoreceptors, chemoreceptors) and relay signals to control centers, which activate effectors such as the kidneys, lungs, skin, and glands. Key processes include osmoregulation, acid-base balance, temperature control, and energy management.

Disruptions to the internal environment can impair cell function and lead to disease. Examples include dehydration, electrolyte disturbances, acid-base disorders, and temperature dysregulation. Severe disturbances may require medical intervention to restore homeostasis.

The concept of the internal environment is central to physiology and medicine; it is associated with Claude Bernard’s milieu intérieur. In clinical practice, laboratory measurements of pH, electrolytes, osmolality, and arterial gases help assess the state of the sisekeskkond and guide treatment to re-establish homeostasis.