The human body is made up of 80% water, which is present in blood and other cells. Since we lose a lot of fluid through sweat, urine, and breath, we need to replenish it constantly. Drinking less water can cause immediate problems. The body cells become dry, and the skin wrinkles. Blood becomes thicker, and the heart has to make more effort to pump it through the body. Since the blood is responsible for transporting oxygen around the body, oxygen is not supplied adequately to the organs. The heart and the brain react immediately to a lack of oxygen-they get damaged in just a few minutes.
Why do we need blood?
Our body consists or millions of cells, which must be supplied with water properly. This supply is the responsibility of the blood. The red blood cells transport vital oxygen around the body. The blood also absorbs nutrients from the digestive tract, distributes them to the organs, and in return, takes away the waste products from the organs. Blood contains platelets that seal the wounds and white blood cells that help us fight disease-causing germs.
How does the heart work?
The heart, a hollow organ with four chambers. can be imagined as an unbelievably strong pump. It is about the same size as a fist. Electrical signals coming from the brain cause the heart muscle to contract about 70 times in a minute in an adult. The contraction are more frequent in children and while we are playing sports. These contractions pump the blood through the whole body through the circulatory system. This system consist of two types of vessels: arteries with blood rich in oxygen and veins with blood poor in oxygen. While the arterial blood supplies oxygen to every cell in the body, the venous blood is sent to the lungs where the it is purified by removing the waste product carbon dioxide and absorbing new oxygen
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