B3.2.2 Transport systems-The blood

a) Blood is a tissue consisting of plasma in which red blood cells, white blood cells, and platelets are suspended.

b) Blood plasma transports:

• Carbon dioxide from the organs to the lungs
• Soluble products of digestion from the small intestine to other organs 
• urea from the liver to the kidneys.

c) Red blood cells transport oxygen from the lungs to the organs. Red blood cells have no nucleus. They are packed with a red pigment called haemoglobin. In the lungs, oxygen combines with haemoglobin to form oxyhaemoglobin…