Water, therefore, is the most important constituent of our body and it is well known that without its contribution from the outside we can only survive for a few days.
and profuse diarrhea, repeated vomiting, burns, pressure sores, polypnea, intake of diuretics, laxatives or particularly low-salt water, high-protein diet, diabetes mellitus, diabetes insipidus, massive consumption of salt).
Dehydration becomes morbid when the loss exceeds 5-6% of body weight.
In basal physiological conditions (at rest) and at room temperature (18-20 °), water losses are less than 1 ml / min.
With physical activity and the increase in external temperature, these losses, mainly due to sweating, can reach 15-25 ml / min.
Although the body is capable of limiting - even considerably - water losses, the importance of water in human nutrition must never be forgotten. It is not uncommon for people who combine a reduced intake of liquids with a diet low in vegetables (consisting of about 90% water) and rich in dehydrating drinks (coffee, alcohol, cola, etc.), with inevitable suffering from " whole organism.
Body water is present in three different compartments:
- Intracellular: it represents 40-50% of the body weight and is very important for the normal development of the metabolic processes of the cells;
- Intravascular: represents 7% of body weight and is the main component of blood plasma;
- Extracellular: it constitutes 17-20% of the body weight, it is found in the spaces between one cell and the other and allows the exchange of substances between the blood of the capillaries and the cells.
Hypertonic dehydration
Hypertonic dehydration is characterized by increased plasma sodium levels (> 145 mmol / L) and hyperosmolarity; it is the typical consequence of profuse sweating and the consequent decrease in plasma volume (loss of excess water on sodium, because sweat is hypotonic, as we will see better later).
Isotonic dehydration
Usually, isotonic dehydration follows from vomiting or diarrhea (loss of water and electrolytes, particularly sodium, in balanced proportions).
Hypotonic dehydration
Hypotonic dehydration is characterized by a drop in plasma sodium levels (hyponatremia) and a reduction in osmolarity;
Hypotonic dehydration is the typical consequence of the abuse of diuretics or rehydration with low sodium water (be careful, in summer, associating low-sodium diets with the consumption of low-residue water can be dangerous: salt is not an absolute enemy; its moderate intake is correct, but not its complete abstinence).
It is no coincidence, therefore, that many people report that they are still thirsty despite drinking a lot of water low in salts.
For further information: Dehydration: the Symptoms
Dehydration: Typical symptoms in adults
In the "adult human being, dehydration typically manifests itself with:
- Extreme thirst;
- Less frequent urination
- Dark colored urine;
- Fatigue;
- Dizziness;
- Confusion.
Dehydration: Typical Symptoms in the Child
In infants and children, dehydration presents with:
- Dry mouth and tongue
- Absence of tears when crying
- Dry diaper for more than three hours (this is indicative of infrequent urination)
- Sunken eyes;
- Listlessness and irritability.
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