The main job of red blood cells, or erythrocytes, is to carry oxygen from the lungs to the body tissues and carbon dioxide as a waste product, away from the tissues and back to the lungs. The body contains about 5 to 6 quarts (about 5 liters) of blood. Blood performs various essential functions as it circulates through the body:

It has four main components: Plasma, red blood cells, white blood cells, and platelets. The blood that runs through the veins, arteries, and capillaries is known as whole bloodÒ€a mixture of about 55% Ò€¦ Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away Ò€¦ Detailed information on blood, including components of blood, functions of blood cells and common blood tests. Blood is a specialized fluid that constantly flows throughout your body. ItÒ€ℒs made of plasma, red blood cells, white blood cells and platelets.

Detailed information on blood, including components of blood, functions of blood cells and common blood tests. Blood is a specialized fluid that constantly flows throughout your body. ItÒ€ℒs made of plasma, red blood cells, white blood cells and platelets.