Blood
Blood is truly the source of life. It carries oxygen to the tissues and removes carbon dioxide and other wastes. The course of the flow of blood is a mainstay of anyone who studies health. Every medical school begins with classes in anatomy and physiology which at times will focus on learning about the blood.
Blood is born in the bone marrow. From there it enters the circulatory system. There its task will be as a carrier. Most people think that blood is bright red, but it only is so in the presence of oxygen. In the oxygen poor blood areas of the body, it is blue. This is why veins are blue and people whose circulation is cut off to a certain body part will have that part turn a purplish hue. Even if a vein is cut, once the blood comes in contact with oxygen from the air, it becomes its brilliant crimson.
The health of the body depends upon how well the blood flows. It makes its way through the heart which pumps the blood to the lungs. There, it picks up oxygen molecules which attach themselves to the hemoglobin in the red blood cells. This is what give red blood cells their name. The hemoglobin is a protein which requires the ingestion of iron to be made. A person who takes in too little iron will have poor health and become anemic, since their blood will not be able to hold as much oxygen.
After the lungs, the blood flows through the arteries into smaller canals called capillaries which surround the tissues. It releases the oxygen there, picks up carbon dioxide and returns through the veins to the lungs, via the heart.
The blood is critical to the health of all, and knowing more about how it works can help one to better their habits to improve their health and prevent disease.