Individuals who want to donate whole blood or apheresis must be : At least 16 years old (donors under the age of 17 may only donate whole blood, and must have a signed parental/guardian consent form). At least 19 years old and weigh a minimum of 110 pounds.
Your heart handles blood in much the same way. The heart pumps about 2,000 gallons (7,571 liters) of blood a day through its chambers. Of Â­course, we're not big enough to hold that much liquid, so it just pumps the same blood over and over, and it doesn't benefit from a drop of it. At least, not initially.
The heart pumps blood along two pathways in your body, the pulmonary circuit and the systemic circuit. In the pulmonary circuit, the heart pumps blood to the lungs, then back to the heart. From this pathway, blood picks up oxygen and drops off carbon dioxide in the lungs. Put simply, blood is oxygenated in the lungs.