Dorst

Dorst, in physiological terms, is the conscious sensation that drives the intake of water. It arises when the body’s fluid balance shifts toward higher concentration or lower volume, signaling the need to restore hydration. In humans, thirst is a key component of maintaining extracellular fluid osmolality and blood volume.

The primary regulatory system for thirst involves the hypothalamus. Osmoreceptors in areas such as the organum vasculosum of the lamina terminalis and the subfornical organ detect increases in plasma osmolality. This information is conveyed to thirst centers in the hypothalamus, promoting the urge to drink. Volume depletion, sensed by baroreceptors, also stimulates thirst via hormonal pathways, notably angiotensin II. Dry mouth can accompany thirst but is not a requisite signal.

Thirst is coordinated with other homeostatic responses. Antidiuretic hormone (vasopressin) is released to promote water reabsorption by the kidneys, working alongside thirst to restore fluid balance. Several factors modulate thirst, including physical activity, environmental temperature, age, and health status. Notably, aging can reduce the sensation of thirst, increasing the risk of dehydration.

Clinically, abnormal thirst can indicate underlying conditions. Diabetes insipidus, whether central or nephrogenic, causes excessive thirst and large volumes of dilute urine due to impaired water regulation. Psychogenic polydipsia involves excessive fluid intake without a physiological trigger. Understanding dorst helps in diagnosing hydration-related disorders and in managing fluid balance across health and disease.