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Excretion


Urinary system

What is not assimilated by the body

What the body does not assimilate, that is, materials that are useless or harmful to its functioning, must be eliminated.

Observe, for 24 hours, everything your body eliminates - the waste - will surely appear: feces, urine, sweat

Are the materials unnecessary for your body's functioning and expelled by it the same?

- No. There is water, solid substances (in the feces), etc.

Our cells produce many wastes that must be eliminated (excreted) from the body. These wastes are called excreta.

Waste formed from the chemical reactions taking place inside cells can be eliminated by:

  • of the respiratory system (carbon dioxide)
  • of the skin (sweat)
  • urinary system (urine)

The skin and urinary system are in charge of eliminating from our body the residues of the activities of the cells and also the substances that are in the blood, expelling them in the form of sweat (through the skin) and urine (through the urinary system). . The respiratory system is in charge of eliminating carbon dioxide from our body.

Do not confuse feces with excreta!

The feces are mainly formed by the remains of undigested food; excreta are products of cell activity and also substances that are in excess in the blood.

Sweat is a liquid produced by sweat glands, which are found on the skin. There are about two million sweat glands scattered throughout our body; most of them are located on the forehead, armpits, palms and soles.

Sweat contains mostly Water, in addition to other substances such as urea, uric acid and sodium chloride (the cooking salt). The substances contained in sweat are drawn from the blood by the sweat glands. Through the excretory canal - the sweat duct - they reach the surface of the skin, exiting through the pores. By eliminating sweat, sweat gland activity contributes to body temperature maintenance.

O man is a homeothermic animal, that is, it keeps the body temperature practically constant, around 36.5 ° C. When we exercise (soccer, running, lifting heavy objects, etc.), the great muscle activity produces a lot of heat and the body temperature tends to increase, so we eliminate sweat; The water contained in the sweat evaporates on the skin, causing a reduction in the temperature of the surrounding air. This favors the loss of heat from the body to the environment, a fact that contributes to the maintenance of our body temperature.