The components of blood are:
- Red blood cells
- White blood cells
Each component makes up a different proportion of the blood. Red blood cells make up around 45%, white blood cells and platelets make up around 1%, and plasma makes up around 55% of the blood.
Red blood cells
Red blood cells are also known as erythrocytes. These are produced in the bone marrow. They carry oxygen and nutrients around the body. Red blood cells contain a protein called haemoglobin. Haemoglobin helps to carry oxygen from the lungs to the rest of the body. This is what makes blood the colour red. Carbon dioxide is then returned from the body to the lungs to be exhaled.
White blood cells
White blood cells are known as leukocytes. These are nucleated cells that fight infections to keep us healthy, so when you get sick it is the production of white blood cells that helps you to fight the cause of your illness.
Platelets are also known as thrombocytes. These are fragments that help to stop bleeding and help to heal wounds by forming blood clots. So when you bleed from an injury or wound, it’s the platelets that work too quickly for blood clots to stop too much blood from bleeding out.
Plasma is the yellow liquid in which red blood cells, white blood cells, and platelets are carried. Blood plasma contains mainly water and other useful waste products. It contains proteins and hormones which help with the body’s functions. Plasma also helps to regulate bleeding and clotting.