Question

Which of the following applies to the Bohr effect ?
A) Effect of $Co_2$ and $H^+$ on the oxygen affinity of haemoglobin
B) Partial pressure of $O_2$ in pulmonary veins
C) Exchange of chloride and bicarbonate ions between RBC and plasma
D) Partial pressure of $O_2$ in systemic arteries

Answer 1

Binding of oxygen with haemoglobin is primarily related to partial pressure of $O_2$, partial pressure of $Co_2$ , hydrogen ion concentration and temperature are the other factors which can interfere with this binding . A sigmoid curve is obtained when percentage saturation of haemoglobin with $O_2$ is plotted against the $po_2$. This curve is called oxygen dissociation curve and is highly useful in studying the effects of factors like $pco_2$, $H^+$ concentration etc. , on binding of $O_2$ with haemoglobin .

Complete answer:

When there is high partial pressure of $O_2$ , low partial pressure of $Co_2$ and lesser hydrogen ion concentration with lower temperature the factors are all favourable for the formation of oxyhaemoglobin .
When there is low partial pressure of $O_2$ high partial pressure of co2 and high hydrogen ion concentration and higher temperature , the conditions are favourable for dissociation of oxygen from the oxyhaemoglobin .
The Bohr effect which is the physiological phenomenon according to which haemoglobin oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide .
That is , the bohr effect refers to the shift in oxygen dissociation curve caused by change in the consideration of carbon dioxide or the pH of the environment .

Hence the correct answer is (A).

Note: Every hundred ml of oxygenated blood can deliver around 5 ml of $O_2$ the tissue under normal physiological condition.And every hundred ml of deoxygenated blood can deliver approximately 4 ml of $O_2$ to the alveoli.