Question

Select the favourable conditions required for the formation of oxyhaemoglobin at the alveoli

• A. Low pO2 , low pCO2 , more H+, higher temperature
• B. High pO2 , low pCO2 , less H+, lower temperature
• C. Low pO2 , high pCO2 , more H+, higher temperature
• D. High pO2 , hig

Answer 1

The Correct Option is B

To understand the conditions required for the formation of oxyhaemoglobin at the alveoli, we need to consider the physiological context where hemoglobin binds to oxygen in the lungs. The process of oxyhaemoglobin formation in the alveoli is driven by certain key factors:

1. High Partial Pressure of Oxygen (pO₂): Alveoli are the site of gas exchange in the lungs, where oxygen is abundant due to inhalation. A high pO₂ enhances the binding affinity of hemoglobin for oxygen.
2. Low Partial Pressure of Carbon Dioxide (pCO₂): In the lungs, CO₂ is exhaled, and its concentration is lower compared to tissues. A low pCO₂ favors oxygen binding to hemoglobin by reducing the formation of carbaminohemoglobin.
3. Low Hydrogen Ion Concentration (Less H⁺): A lower concentration of H⁺ (indicating a higher pH) promotes the binding of oxygen to hemoglobin. This is because increased H⁺ ions (lower pH) shift the hemoglobin to release oxygen in a process known as the Bohr effect.
4. Lower Temperature: Cooler temperatures enhance the affinity of hemoglobin for oxygen. In the alveoli, the temperature is relatively lower compared to metabolically active tissues.

Given these conditions, the correct answer is High pO₂, low pCO₂, less H⁺, lower temperature. These factors collectively facilitate the efficient loading of oxygen onto hemoglobin in the lungs.

Other options can be ruled out as follows:

• Low pO₂: This would not favor oxygen binding as there is insufficient oxygen pressure.
• High pCO₂, More H⁺, Higher Temperature: These conditions are characteristic of tissues rather than alveoli, promoting oxygen release rather than binding.