B3 2.3 Transport in the blood

Your blood is a tissue that consists of a fluid called plasma. Plasma carries red blood cells, white blood cells and platelets suspended in it. it also carries many dissolved substances around your body. The average person has between 4.7 and 5.0 litres of blood.

The blood plasma as a transport medium

Your blood plasma is a yellow liquid. The red colour of your blood comes from the red blood cells. The plasma transports all of your blood cells and some other things around your body. Carbon dioxide produced in the organs of the body is carried back to the lungs in the plasma.

Similarly, urea is carried to your kidneys in the plasma. Urea is a waste product formed in your liver from the breakdown of proteins. In the kidneys the urea is removed from your blood to form urine.

All the small, soluble products of digestion pass into the blood from your small inestine. These food molecules are carried in the plasma around your body to the other organs and individual cells.

Red blood cells

The red blood cells pick up oxygen from your lungs.…