Donating Blood...

About Blood

Everyone has it and statistics show that one in three people will need it at some point in their life. But what do you really know about “blood”? This section will provide you with some basic information about the liquid makeup of the human anatomy.

What is blood?
Blood is a liquid that circulates through the body by means of the heart carrying oxygen, nutrients, and minerals to all cells of the body. It also carries away waste products such as carbon dioxide back to the lungs, kidneys, and liver for disposal. Blood components fight against infection and helps heal wounds in order to stay healthy. The four main blood components are Red Blood Cells, White Blood Cells, Platelets, and Plasma, all with a unique and vital function. Blood components have different life spans in the blood stream: Red Blood Cells last approximately 120 days; platelets approximately 10 days; white blood cells can last anywhere from days to years.

Blood Cells Are Produced
In Marrow
Red cells, white cells, and platelets are made in the marrow of bones primarily in the vertebrae, ribs, hips, skull, and sternum. These essential blood cells which develop from stem cells in the bone marrow fight infection, carry oxygen, and help control bleeding.

Ribs Marrow

Plasma Carries Blood Cells
Plasma is a clear, pale yellow mixture of water, proteins, and salts. One of its major functions is to act as a carrier for the blood cells, nutrients, enzymes, and hormones. More than half of the blood volume consists of plasma which is approximately 90% water.

Red Cells

Red Cells Deliver Oxygen
Red cells (Erythrocytes) are disc-shaped cells containing hemoglobin which pick up and deliver oxygen to all parts of the body. They also deliver carbon dioxide back to the lungs to be exhaled. Red Blood Cells constitute approximately 40 – 45% of the total blood volume.

Photo Copyright: Dennis Kunkel,
University of Hawaii

White Blood Cells Defend the Body
White Cells White Blood Cells (Leukocytes) are the body's primary defense against infection. They can move out of the blood stream and reach tissues being invaded by viruses or bacteria.

Platelets Help Control Bleeding
Platelets (Thrombocytes) are small cells in the blood that help control bleeding. When activated to form clots, these cell fragments become irregular-shaped and cluster together at the site of the wound.