Human Physiology Mechanism Of O2 And Co2 In Human Body

HUMAN PHYSIOLOGY :MECHANISM OF O2 AND CO2 IN HUMAN BODY Exchange Breathing is the activity of taking in and exhaling respiratory air through the lungs. A more specific meaning is the gas exchange that occurs in the cell with its "environment". In direct breathing, breathing air is taken directly by the surface of the body and in indirect breathing through the respiratory tract. Humans breathe indirectly, meaning that the air they breathe does not diffuse directly through the entire surface of the skin. The thin membrane where gas diffusion takes place is protected inside the body, in the form of the lung bubble (alveolus). Respiration or gas exchange in humans takes place in two stages, namely external respiration and internal respiration. External Breathing External breathing is the exchange of gases in the lungs. Therefore, diffusion of gas from outside into the bloodstreamtakes place. In other words, external respiration is an exchange of gases (O2 and CO2) between air and blood.During external respiration, blood will enter the lung capillaries which transport most of the carbon dioxide as bicarbonate ions (HCO3 –) with a reaction equation as follows. H+ + HCO3 – H2CO3 The remaining carbon dioxide diffuses out of the blood and carry out the following reaction. H2CO3 H2O + CO2 The carbonic anhydrase enzyme found in red blood cells can speed up the reaction. As the reaction progresses, hemoglobin releases the hydrogen ions it has transported; HHb becomes Hb. Hb is an abbreviation of hemoglobin, which is a type of protein in red blood cells.Next, hemoglobin binds oxygen and becomes oxyhemoglobin (HbO2). Hb + O2 HbO2 During external respiration, gas exchange occurs in the lungs, namely CO2 leaves the blood and O2 enters the blood by diffusion. This diffusion of O2 and CO2 occurs due to differences in partial pressure. The external air pressure is 1 atm (760 mmHg), while the partial pressure of O2 in the lungs is ± 160 mmHg. Partial pressure in arterial blood capillaries is ± 100 mmHg, and in veins is ± 40 mmHg.This causes O2 from the air to diffuse into the blood.Meanwhile, the partial pressure of CO2 in the veins is ± 47 mmHg, the partial pressure of CO2 in the arteries is ± 41 mmHg, and the partial pressure of CO2 in the alveoli is ± 40 mmHg. The difference in partial pressure causes CO2 to diffuse from the blood to the alveoli. Deep (Internal) Breathing In deep breathing (gas exchange in body tissues) blood enters body tissues, oxygen leaves hemoglobin and diffuses into body tissue fluids. The reaction is as follows. HbO2 Hb + O2 Diffusion of oxygen out of the blood and into the tissue fluid can occur, because the oxygen pressure in the tissue fluid is lower than in the blood. This is because cells continuously use oxygen in cellular respiration.The respiratory process that occurs in the tissues causes differences in the composition of the air entering and leaving the lungs. It should be noted that the partial pressure of O 2 in the pulse blood capillaries is ± 100 mmHg and the partial pressure of O2 in body tissues is less than 40 mmHg. On the other hand, carbon dioxide pressure is high, because carbon dioxide is continuously produced by body cells. The partial pressure of CO2 in tissue is ± 60 mmHg and in blood capillaries ± 41 mmHg. This is what causes O2 to diffuse into the tissue and CO2 to diffuse out of the tissue.Under normal circumstances, our body produces 200 ml of carbon dioxide per day. Transport of CO2 in the blood can be done in the following three ways. 1) About 60–70% of CO2 is transported in the form of bicarbonate ions (HCO3 –) by blood plasma, after the carbonic acid formed in the blood decomposes into hydrogen ions (H+) and bicarbonate ions (HCO3 –).The H+ ion is toxic, therefore this ion is immediately bound to Hb, while the HCO3 - ion leaves the erythrocytes and enters the blood plasma. The position of the HCO3 – ion in erythrocytes is replaced by chlorite ions.The reaction equation is as follows. H2O + CO2 H2CO3 H+ + HCO3 2) Approximately 25% of CO2 is bound by hemoglobin to form carboxyhemoglobin. In simple terms, the reaction of CO2 with Hb is written as follows. CO2 + Hb HbCO2 Carboxyhemoglobin is also called carbominohemoglobin because the part of hemoblogin that binds CO2 is an amino acid group.The reaction is as follows. CO2 + RNH2 RNHCOOH 3) Approximately 6–10% of CO2 is transported by blood plasma in the form of carbonic acid compounds (H2CO3).You can find out more about the carbon dioxide content in your breath by doing the following activities. Not all CO2 transported by the blood through the lungs is released into the air. Blood passing through the lungs only releases 10% CO2. The remaining 90% remains in the blood in the form of bicarbonate ions.These bicarbonate ions in the blood act as a buffer because they play an important role in maintaining blood pH stability.If there is a disruption in the transport of CO2 in the blood, carbonic acid (H2CO3) levels will increase, causing a decrease in blood alkali levels which act as a buffer solution. This will cause a physiological disorder called acidosis.