2.57 describe the composition of the blood: red blood cells, white blood cells, platelets and plasma

 The blood is made up of many different components:

Red blood cells:

-        40% of blood is red blood cells

-        they transport oxygen around the body

-        also known as erythrocytes

White blood cells:

-        5% of blood is white blood cells

-        they protect the body against infectious diseases and foreign invader

-        there are 2 main types of WBCs:  lymphocytes and phagocytes

-        also known as leukocytes

Plasma:

-        50% of the blood is made of plasma

-        it is a yellow liquid containing water and other substances dissolved in it

-        it holds the blood cells in suspension

Platelets:

-        5% of blood is platelets

-        important for clotting

-        platelets are fragments of a bigger cell

-        no nucleus