Since it is the circulation of blood that keeps the body healthy by providing food to the tissues and eliminating their wastes, it is necessary to know something about blood and its circulation.
The circulation of blood is performed by the means of a muscular pump, which is the HEART. The muscles of heart contract periodically and cause the heart to pump blood. The blood is carried to different parts of the body through arteries and capillaries.
Arteries are larger and they take blood from the heart to supply it to various tissues via (the smaller) capillaries, while the veins return blood from the tissues to the heart.
The blood that is carried from the heart to the tissues in the arteries (the arterial blood) is rich in oxygen and dissolved foods, while the blood in the veins (the venous blood) that is carried back from the tissues to the heart via the lungs, contains carbon dioxide and waste material, which is supplied first to the lungs by the pulmonary artery.
From the lungs, the pulmonary vein supplies the purified blood rich with oxygen, back to the heart, thus completing one cycle of blood-circulation in the body.
This process goes on repeatedly in the body, the blood performing the distribution of food to the tissues and then cleaning them of the CO2 and waste material. The dual function of supply and drainage, by the blood, goes on in the system, the heart contracting each time and thus performing the circulating function, which it does 72 times in a minute in an adult person.
This rate increases to 100 or more during activity or excitement. The total volume of blood in the system is about 5 or 6 liters, while the heart pumps out about 5 liters of blood every minute.
The blood, in this way, performs not only the function of providing nourishment, in its supply of blood to the tissues, but also performs the function of purification in the tissues, by eliminating their poisonous CO2 gas and the waste materials.
Also, due to wrong ways of living, when foreign matter gets accumulated on the inner walls of the arteries and the capillaries, and the free circulation of blood gets impaired, it is the renewed blood-circulation by cold water treatments, that causes the oxidation of impurities and restores the blood-circulation system.
So, this is the important function performed by blood in its circulation. In a separate chapter, on nutrition of the body, we shall explain further the function of blood in providing nutrition to the body-cells.
Here, we have confined ourselves to giving just an idea of the circulation of blood, and the effect of cold water on its restoration.