How is oxygen and carbon dioxide transported in human beings?
Answers
i) Oxygen enters the blood from the lungs and carbon dioxide is expelled out of the blood into the lungs.
ii) The blood serves to transport both gases.
iii) Oxygen is carried to the cells.
iv) Carbon dioxide is carried away from the cells.
Respiration is the process through which living organisms take in oxygen and give out carbon dioxide to release energy. So, naturally, respiration is a major and vital process of gas exchange. The transport of gases during respiration, both oxygen and carbon dioxide are carried out by the blood cells
During respiration, about 97% of oxygen is transported by Red Blood Cells in the blood and the remaining 3% gets dissolved in the plasma. Haemoglobin transports oxygen molecule to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to O2 molecules that are obtained from breathing and thus forms oxyhaemoglobin. This oxygenated blood is then distributed to all the body cells by the heart. Since haemoglobin pigment has less affinity for CO2, CO2 is mainly transported in the dissolved form. This deoxygenated blood gives CO2 to lung alveoli and takes O2 in return. Around 20-25% of carbon dioxide is carried by haemoglobin as carbamino-haemoglobin. 7% is in a dissolved state in the plasma and the remaining is carried as bicarbonate. Again, the binding of carbon dioxide with haemoglobin is related to the partial pressure of carbon dioxide, and the partial pressure of oxygen. As mentioned earlier, the partial pressure of carbon dioxide is high in the tissues and this is where more binding of carbon dioxide occurs. In the alveoli where the partial pressure of oxygen is high, carbon dioxide gets dissociated from carbamino-haemoglobin