Explain the relationships among O2 and CO2 transport and acid-base balance.
Explain the relationships among O2 and CO2 transport and acid-base balance.
The cells are the basic unit of life and their proper and are responsible for the formation of tissues and organs in the humans. The requirements of nutrients and oxygen are vital for the cells to perform their function efficiently. These requirements are met by taking up food, water and air. The aerobic conditions essential for cellular respiration are fulfilled by the breathing. The process of breathing includes inhalation of air containing oxygen from the nose which then moves through the respiratory system to reach the lungs. The lungs are a vital human organ where exchange of gases takes place. The oxygen is breathed in from the environment whereas carbon dioxide is breathed out. These inhaled oxygen dissolve in the blood after reaching the lungs, the resulting oxygen rich blood is pumped by the heart and is circulated in the whole body so it reaches each and every part whereas carbon dioxide is collected from the organs which is transported back to lungs and finally exhaled out by the body.
The oxygen is transported in the blood by either of the two methods: direct dissolution into the blood, and by the help hemoglobin molecule. The first method is where the inhaled oxygen directly diffuses from the alveoli of the lung into the blood present in the pulmonary capillaries. However, the majority of oxygen transport in blood occurs through hemoglobin pigments and very little amount is directly diffused in the blood. The hemoglobin is a predominant protein pigment present in the red blood cells that forms a reversible bond with oxygen.
The carbon dioxide, on the other hand, can be transported in the body by three possible methods: by direct dissolution into the blood, by binding to hemoglobin present in blood, and it can be transported in the form of bicarbonate ions in the blood. Of the three possible methods, only a small amount of carbon dioxide actually diffuses in the blood. Like oxygen, carbon dioxide can also form reversible bonds with the hemoglobin molecule. In the state where hemoglobin is bonded to oxygen it is called oxyhemoglobin, and if bonded to carbon dioxide it is called carbaminohemoglobin. The major transportation of the CO2 occurs in the form of bicarbonate ions. The enzyme present in blood which catalyses the conversion of CO2 into the bicarbonate ions (HCO3-) is carbonic anhydrase. This enzyme is and converts the carbon dioxide into carbonic acid (H2CO3). The carbonic acid form is an unstable molecule and hence it dissociates into bicarbonate and hydrogen ions. Upon reaching the lungs, these bicarbonate ions are converted back to the CO2 which is exhaled out by the body. The reaction catalyzed by the carbonic anhydrase is given as below.
CO2+H2O ⟷ H2CO3 (carbonic acid) ⟷ HCO3- (bicarbonate ion) + H+ (hydrogen ion)
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