Blood Why We Need It Just about everyone knows that we can't live without blood. And that the blood in our bodies is pumped by the heart through a network of arteries and veins. But beyond those blood basics, what do you know about that red stuff beneath your skin?
Blood is essential for good health because the body depends on a steady supply of fuel and oxygen to reach its billions of cells. Even the heart couldn't survive without blood flowing through the vessels that bring nourishment to its muscular walls. Blood also carries carbon dioxide and other waste materials to the lungs, kidneys, and digestive system; from there they are removed from the body.
Without blood, we couldn't keep warm or cool off, we couldn't fight infections, and we couldn't get rid of our own waste products.
So how exactly does blood do these things? How is it made, and what's in it? How does blood clot? It's time to learn a little about the mysterious, life-sustaining fluid called blood.
What Is Blood and What Does It Do? Two types of blood vessels carry blood throughout our bodies: The arteries carry oxygenated blood (blood that has received oxygen from the lungs) from the heart to the rest of the body. The blood then travels through the veins back to the heart and lungs, where it receives more oxygen. As the heart beats, you can feel blood traveling through the body at your pulse points — like the neck and the wrist — where large, blood-filled arteries run close to the surface of the skin.
The blood that flows through this network of veins and arteries is called whole blood. Whole blood contains three types of blood cells:
1. red blood cells 2. white blood cells 3. platelets In babies and young children, blood cells are made in the bone marrow of many bones throughout the body. But as kids get older, blood cells are made mostly in the bone marrow of the vertebrae (the bones that make up the spine), ribs, pelvis, skull, sternum (the breastbone), and parts of the humerus (the upper arm bone) and femur (the thigh bone).