Other names: polydipsia, excessive thirst
Thirst is a sensation of fluid intake needs. Whether feel thirsty, decides in particular part of the brain called the hypothalamus. Cells are located, which are in contact with the flowing blood and respond to its composition.
If the levels are high solute concentrations, these cells will send a signal that is needed blood diluted with water – that is we drink.
The feeling of thirst is also influenced by filling blood vessels and blood pressure – in the large veins and arteries are positioned so called baroreceptors, which informs the brain of the pressure in the blood vessels. Small filling venous or low blood pressure, thus also contributing to the feeling of thirst, but this mechanism will apply until at greater water loss.
The feeling of thirst also affect the receptors in the oral cavity and pharynx. Therefore, when the drink (particularly something cold), it immediately drops thirst, although the beverage still could doputovat into the bloodstream and the diluted blood in the hypothalamus. On the other hand, a dryness in the oral cavity enhances the feeling of thirst.
The sensation of thirst is often reduced in older people, so they should drink regularly even if you do not feel thirsty.
Excessive thirst is technically called polydipsia and may be a symptom of serious illness, it is typically the first symptom of diabetes (diabetes mellitus), which is guided in polyuria (excessive urination), and fatigue.
Another disease that is accompanied by increased thirst is “thirsty” – diabetes insipidus, which has two forms – central and renal. When the central form is impaired secretion of antidiuretic hormone, causing water reabsorption in the kidney.
When there is a lack of this hormone, the kidneys are unable to concentrate urine, the body loses water excessively and the patient is constantly thirsty. Renal form of this disease is congenital, antidiuretic hormone is plentiful, but the kidneys do not respond to.
Increased thirst may be present in other metabolic disorders, such as elevated thyroid function orexcess calcium in the blood.
Also, when xerostomia – dry mouth due to reduced saliva production, will feel sick constantly thirsty.
Increased thirst but can also be a normal reaction of the organism to increased fluid loss with increased physical work or during their stay in the heat or in an environment where the air is dry.
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