Skin
Water
Life has evolved in the presence of water since the beginning of life on earth. Water molecules surround the majority of the cells and the cells themselves are composed mostly of water.
Water is involved in all chemical reactions essential for our body. Yet we are talking about a very simple molecule whose exceptional qualities are often forgotten.
It has four fundamental qualities: cohesion that allows the conveyance of water and the active ingredients dissolved in it.
Adhesion that offsets the force of gravity. A surface tension greater than that of most substances in their liquid state. When water interfaces with the air it behaves as if it were covered by a transparent film. Water moderates thermal excursions, stabilising the temperature of the air by absorbing heat when it is warmer or releasing heat when the air is colder. A newborn has a water content that reaches 75% of body weight, this value decreases with age. In adults, water accounts for about 60% of body weight, distributed in 40% intracellular and 20% extracellular water.
The electrolyte content of the two compartments varies at a qualitative level, i.e. the ions are represented in different percentages. This determines some important properties:
- water carries nutrients and discards waste products;
- it is the gas, electrolyte and colloid solvent;
- it is the medium where all the digestive and metabolic reactions take place;
- it participates in the mechanisms of thermoregulation and maintenance of thermal equilibrium among the cells;
- it has a plastic function which plumps the cells.