Blood is made up of two parts:
- Fluid (plasma or serum)
Plasma contains various substances including glucose, electrolytes, proteins, and water. Serum is the fluid part that remains after the blood is allowed to clot in a test tube. Specifically, serum is the fluid part of blood after a substance called fibrinogen has been removed by clotting.
Cells in the blood include red blood cells, white blood cells, and platelets.
Blood helps move oxygen, nutrients, waste products, and other materials through the body. It helps control body temperature, fluid balance, and the body's acid-base balance.
Tests on blood or parts of blood may give your doctor important clues about your health.