The Circulatory System

The blood is the transport system by which oxygen and nutrients reach the bodys cells, and waste materials are carryed out.

The heart, a muscular organ, positioned behind the ribcage and between the lungs, is the pump that keeps this transport system running.

Blood that is rich in oxygen appears  red.                               Blood that is poor in oxygen appears blue.

Blood leaves the left side of the heart traveling through the arterieswhich gradually divided into cappillaries. In the capillaries, food and oxygen are released to the body cells, and carbon dioxide and other waste products arereturned to the bloodstream. The blod then travels throw the veins and back to the right side of the heart, where it is pumped directly to the lungs. In the lungs, carbon dioxide is exchanged for oxygen, this renewed blood flows back to the left side of the heart, then it happens all over again.

Facts

The heart beats around 3 billion times in a average persons life time.

About 8 million cells die every second and the same amount is born.

Within a drop of blood, there is 5 million red blood cells.

It takes 20 seconds for a red blood cell to circle the whole body.

Continue...