Question

What is the effect of the following changes in the O2 affinity of hemoglobin? (a) A drop in the pH of blood plasma from 7.4 to 7.2. (b) A decrease in the partial pressure of CO2 in the lungs from 6 kPa (holding one’s breath) to 2 kPa (normal). (c) An increase in the BPG level from 5 mM (normal altitudes) to 8 mM (high altitudes). (d) An increase in CO from 1.0 part per million (ppm) in a normal indoor atmosphere to 30 ppm in a home that has a malfunctioning or leaking furnace.

Answer 1

The affinity of hemoglobin for O₂ is regulated by the binding of the ligands H+ , CO2

and BPG. The binding of each ligand shifts the O₂ -saturation curve to the right—that is, the

O₂ affinity of hemoglobin is reduced in the presence of ligand.

(a)

A pH drop will increase the affinity for oxygen to myoglobin and decrease the affinity of oxygen for haemoglobin. This means less O2 will be taken in at the lungs and more will be off loaded at the tissues

decreases the affinity;

(b)

A decrease in the partial pressure of CO2 will increase oxygens affiniy to haemoglobin and decreases it's afinity for myoglobin

increases the affinity;

(c)

An increase in BPG levels decreases oxygens affinity for haemoglobin nd increases its affinity for myoglobin

decreases the affinity;

(d)

An increase in CO levels decreases oxygens affinity for haemoglobin and increases its affinity for myoglobin

decreases the affinity