Question

1. Describe the concept of P50; compare P50 from various conditions and taxa and explain how these may be adaptations to their environments.

2. Diagram and describe the removal of CO2 from working tissues and release to the environment.

3. In what form is most CO2 transported? What factors affect CO2 transport?

Answer 1

• P50 is a oxygen tension at which heamoglobin is 50% saturated with oxygen.
• Normal P50 is 26.7mmHg
• It represents haemoglobin-oxygen affinity.
• oxyhaemoglobin dissociation curve is represent the haemoglobin-oxygen affinity.:-the rightward shift increase P50 and lowers haemoglobin's affinity for oxygen. and a leftward shift decrease P50 and lowers haemoglobin's affinity for oxygen .
• factors affecting the oxyhaemoglobin dissociation curve are

1) Bohr effect :-A decrease in PH shifts the curve to right and a incresed PH shifts the curve to left.It comes into action everytime arterial blood traverses to capillaries.

2)Hypoxemia,chronic lung disease,congestive heart failure,anemia increase the production of 2,3-diphosphoglycerate it is synthesized during glycolysis ,this causes shift the oxyhaemoglobin dissociation curve to right.On the other hand the conditions like septic shock ,hypophosphatemia decrease the production of 2,3 -diphosphoglycerate this causes the curve to left.

3) temperature also has a effect on oxyhaemoglobin dissociation curve.Hypothermia causes a curve to leftward shift,and hyperthermia causes rightward shift.

4)Methemoglobinemia causes leftward shift to curve.

5)carbon monoxide also has a effect on shifting the curve to the left.

6)fetal haemoglobin is structurally different from normal haemoglobin.Fetal dissociation curve is left compared with normal adult.This leftward shift enhances the placental uptake of oxygen.