Human blood is red because of the protein hemoglobin, which contains a red-colored compound called heme that’s crucial for carrying oxygen through your bloodstream. Heme contains an iron atom which ...

The blood in your body delivers oxygen to all of your cells. When you breathe and draw fresh oxygen into your lungs, red blood cells bind with the oxygen and carry it through your bloodstream. On a ...

Thin blood means having too few platelets, a part of the blood that helps clots form. Thin blood typically does not cause symptoms but can lead to excessive bleeding and bruising. Blood contains four ...