We’ve all heard about it, seen it, donated it — but what is in blood? What is it made up of?

“Blood is a suspension of red and white blood cells, platelets, proteins, and chemicals in a straw-coloured fluid called plasma.”

You have about 10 pints [or 5 litres] of it in your body, about 8% of your overall weight. At rest, it takes about one minute for the heart to pump it around your body.

Its main components are plasma and blood cells, called corpuscles. The three main corpuscles are: red blood cells [RBCs, or erythrocytes], white blood cells [WBCs, or leukocytes], and platelets [thrombocytes].

Plasma

Plasma is the liquid medium that makes up about 55% of blood. It is 91% water and 9% proteins and other chemicals. Its main function is to circulate dissolved nutrients [glucose, lipids, and proteins] and to transport waste products.

Red Blood Cells

The disc-shaped RBCs are the most plentiful blood cells in your body — about 4 – 6 million per cubic millimetre of blood. Their main job is to transport oxygen to the body’s tissues, carried by an iron-containing compound called hemoglobin. Once the oxygen is delivered to tissues, it is exchanged for carbon dioxide, which hemoglobin carries back to the lungs to be exhaled.

White Blood Cells

You have between 4 – 10 thousand WBCs per cubic millimetre of blood. WBCs are the agents of the body’s immune system. WBCs are dispatched to deal with infections, pathogens, and injury. There are several different types of WBCs: neutrophils and monocytes deal with bacterial and small particle invasions to the body. Lymphocytes are critical for your ongoing immunity, producing antibodies to destroy foreign organisms. Eosinophils and basophils are the other main types of WBCs.

Platelets

Platelets are responsible for the clotting process — the body’s way to stop bleeding and commence the healing process after injury. You have between 250 – 400 thousand platelets per cubic millimetre of blood.

And those are the basics on your blood.