Blood Basics

Are you ever curious about what makes the trillions of cells coursing through your veins so vital to everyday life? This source of life pulsing within each of us is truly wondrous. Learn more about blood—and all of its amazing characteristics.

What is blood?

Blood is a liquid that circulates throughout the body via a pathway of blood vessels, arteries and veins. It carries nutrients, oxygen, antibodies and other necessities of life to every cell and tissue. Blood is also the means by which waste and waste byproducts are removed from cells. The main function of blood is to act as the body’s transport system, but it also has a major role in the body’s defense against infection. Having a healthy supply of blood is important to our overall well being.

Where do blood cells come from?

Red blood cells, white cells and platelets are made in the marrow of bones, especially the vertebrae, ribs, hips, skull and sternum. These essential blood cells, suspended in plasma, fight infection, carry oxygen and help control bleeding.

What are the components of blood and what do they do?

Blood is made of up of several components: red blood cells, platelets and plasma. Each of these components has a very specific and important job.

How were blood types created?

In the early 1900s, Karl Landsteiner—an Austrian biologist, physician, and immunologist—identified the three main blood groups, A, B and O. He also determined that blood either contains a certain protein, or antigen (Rhesus, or Rh factor), on the surface of red blood cells or it doesn’t. If your blood has this protein, you’re Rh-positive; if not, you’re Rh-negative. His groundbreaking work paved the way for advances in transfusion medicine; most notably that blood donor and recipient must have compatible blood to ensure a safe and successful transfusion. Landsteiner earned a Nobel Prize for his discovery.

What are the different blood types?

Blood is grouped into four types: A, B, AB and O. Each type is also classified by an Rh factor–either positive or negative. Your ABO blood grouping and Rh factor are inherited from your parents. Review the chart below to learn more about the representation in our population, the patients you’ll help and the optimal blood components you can give. If you don’t know your blood type, we’ll tell you after you donate.

Remember, no matter what your blood type is, every donor is needed and every donation transforms lives—even your own!