The exchange of gases in :i. the alveoli that lowers thepO2of blood an...
In the alveoli, there is high pO2 , low pCO2 , lesser H+ concentration and lower temperature,
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The exchange of gases in :i. the alveoli that lowers thepO2of blood an...
Explanation:
The exchange of gases in the alveoli and tissues is a vital process in the respiratory system. Let's break down the statements and determine their accuracy:
i. The exchange of gases in the alveoli:
The alveoli are small air sacs located in the lungs where gas exchange takes place. Oxygen from the inhaled air diffuses across the thin walls of the alveoli and enters the bloodstream, while carbon dioxide, a waste product of cellular respiration, moves from the bloodstream into the alveoli to be exhaled.
- Lowering the pO2 of blood: When oxygen diffuses from the alveoli into the bloodstream, it increases the oxygen concentration in the blood, which raises the partial pressure of oxygen (pO2). Therefore, statement i) is incorrect as it states that the pO2 of blood is lowered during external respiration.
- Raising the pCO2 of blood: As carbon dioxide is produced during cellular respiration in the body's tissues, it diffuses from the bloodstream into the alveoli to be exhaled. This process decreases the carbon dioxide concentration in the blood, leading to a decrease in the partial pressure of carbon dioxide (pCO2). Therefore, statement i) is incorrect as it states that the pCO2 of blood is raised during external respiration.
ii. The exchange of gases in the tissues:
The exchange of gases in the tissues occurs between the capillaries and the cells. Oxygen-rich blood from the lungs is transported by the circulatory system to the body's tissues, where oxygen diffuses from the capillaries into the cells, providing the necessary oxygen for cellular respiration. At the same time, carbon dioxide produced by the cells diffuses into the capillaries to be transported back to the lungs for exhalation.
- Lowering the pCO2 of blood: As the cells utilize oxygen for cellular respiration, carbon dioxide is produced as a waste product. This carbon dioxide is transported by the blood back to the lungs to be exhaled. Therefore, statement ii) is correct as it states that the pCO2 of blood is lowered during internal respiration.
- Raising the pO2 of blood: As oxygen is utilized by the cells for cellular respiration, the oxygen concentration in the blood decreases. This leads to a decrease in the partial pressure of oxygen (pO2). Therefore, statement ii) is incorrect as it states that the pO2 of blood is raised during internal respiration.
Based on the explanation above, we can conclude that statement i) is incorrect and statement ii) is correct. Therefore, the correct answer is option 'C' - statement i) is wrong and ii) is correct.
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