Blood is a liquid in humans and many animals except insects. Blood is pushed through the organism by the heart, and brings nutrients and oxygen to our tissues. It also takes away waste and carbon dioxide from tissues.
Blood of vertebrates is made up of blood plasma and various cells — red blood cells, white blood cells and platelets. Platelets help blood to clot. Hemoglobin is in red blood cells. White blood cells help fight infections and heal wounds.
Blood plasma is the yellow liquid in which blood cells float. Plasma is made up of nutrients, electrolytes (salts), gases, non-protein hormones, waste, lipids, and proteins. These proteins are albumin, antibodies (also called immunoglobulins), clotting factors, and protein hormones. Plasma that does not have the protein fibrinogen is called serum and cannot clot. Adults have about 3 liters of plasma. Plasma is a liquid, mostly water (90%). Plasma takes up 55% of volume.

License information: CC BY-SA 3.0 and GFDL
MPAA: PG
Go to source: https://simple.wikipedia.org/wiki/Blood