Thirst, the urgent need to drink, stimulated by the body`s need for water. A thirsty person experiences dryness of the mouth and throat that is usually not relieved until the person consumes liquids. Most of the liquid a person consumes is pure water, or water contained in some other beverage. The rest is obtained from foods and from the small amount of water formed by body cells as a by-product of respiration, the process of breathing by which oxygen in the blood is absorbed by cells.

Although little is known about the mechanism

Although little is known about the mechanism of thirst, it is likely controlled by the drinking center, which is located in the hypothalamus, the part of the brain that controls body functions such as body temperature, hunger, and thirst. The drinking center is probably sensitive to salts. When the amount of water in the body falls below a certain level, the concentration of salts increases and the drinking center is stimulated to create the sensation of thirst. Mouth and tongue dryness may also contribute to the stimulation of thirst.

Thirst is not always present when the body

Thirst is not always present when the body experiences dehydration, or a shortage of body fluids, particularly among the elderly. Dehydration may occur as a result of excessive sweating, overeating, vomiting, diarrhea, or heat exhaustion. The amount and frequency of urination and the color of urine more accurately indicate low body fluid levels than the perception of thirst.

Excessive thirst

Excessive thirst, especially when combined with frequent urination, sudden weight loss, fatigue, and blurred vision may be a symptom of diabetes. The body reacts to high glucose levels in the blood by inducing frequent urination, which leads to constant thirst. If this condition persists, the individual should consult a physician.

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