Explain the transport of oxygen and carbon dioxide in the blood

figure 6

The red blood cells carry oxygen from the lungs to the rest of the body tissues. A small amount of oxygen (1.5 %) is carried in the plasma as a dissolved gas. Most oxygen (98.5 %) carried in the blood is bound to the protein haemoglobin in red blood cells. A fully saturated oxyhaemoglobin has four oxygen molecules attached. Oxygen is transported by blood to enable us to respire which is essential to live.
Carbon dioxide is more soluble in the blood than oxygen, about 5% is transported unchanged. Carbon dioxide combines with haemoglobin to form carbaminohaemoglobin. 10% of carbon dioxide binds to amino groups on the polypeptide chains of haemoglobin and plasma proteins. Carbon dioxide enters red blood cells in the tissue capillaries where it combines with water to form carbonic acid. This is normally a slow reaction, but the RBC is greatly accelerated by an enzyme called carbonic hydrase. (Smith, 2002)
The heart acts as a central pump that keeps the blood moving around the body. When air is inhaled, it enters the lungs and diffuses through the alveoli; the oxygen binds with the haemoglobin of the red blood cells to form oxyhaemoglobin. The blood then enters the pulmonary circulation system, where it gets pumped round to cells that require energy for cellular respiration. Oxygen diffuses out of the red blood cells and carbon dioxide diffuses in making the blood deoxygenated, it then travels back to the lungs and diffuses into the alveoli and is exhaled as the waste product carbon dioxide.
(Class notes, 2010)