Cells

Cells

Apart from water the rest of the body is built from a huge number of complicated chemicals. These chemicals, together with water, are assembled into tiny building blocks called cells. Each cell is self-contained and has a particular function of the body. There are more than 50,000 billion cells in our body. The shape and appearance of a cell depends on what type of job it has to do. Nerve cells are long and thread – like and can carry messages around the body along the nervous system. Red blood cells are so tiny that they can only be seen under a microscope and are like flattened discs.

The sole function of the blood cell is to combine with oxygen in the lungs and to exchange the oxygen for carbon dioxide in the tissues. White blood cells are shapeless so they can squeeze between other cells and attack invaders such as bacteria. Other cells control the production of essential substances called proteins.

Water

Water

Water is absolutely essential to every single form of life. Every living cell – plants and animals alike – depend on this substance. More than half of the human body is made up of water. Much the same time is true of other living things. Without water to drink, human beings would die in a very short time. The reason every living thing needs a certain amount of water is because the cells, the basic units that make up living things, have water molecules in them. Without water these basic units would be very different and of no use to life as we know it. In the course of a day, an adult human being takes in about two quarts in what we call solid foods, such as fruit, vegetables, bread, and meat.

These solid foods are not really dry, since they are thirty to ninety percent water. Besides these three quarts that enter the body from outside, about ten quarts of water pass back and forth within the body between the various organ systems. There are about five quarts of blood in the vessels of the body and three quarts of this is water. And this always remains unchanged. No matter how much water you drink you cannot dilute the blood.

Our sense of thirst is controlled in the brain. When the body requires more water, we experience the sensation of thirst. Usually our mouth and throat become dry – a signal for us to drink more fluids.