Respiratory 25

Question 1

What is Cooperative Binding?

Answer 1

When O2 binds to a heme group and deforms the shape of the heme group which changes the shape of its associated globin chain from the tense to relaxed state and facilitates the binding of additional O2 molecules

Question 2

What produces the characteristic sigmoidal binding curve of HB?

Answer 2

Cooperative binding

Question 3

What are the two sections of Sigmoidal Dissociation curve?

Answer 3

1. A flat portion (plateau) between 60 - 100 mmHg

2. Steep portion between 10 - 60 mmHg

Question 4

What is the advantage to having to plateau of O2 saturation at 100%?

Answer 4

Saturation stays high over a wide range of PO2. So even a significant limitation of lung function still allows almost normal O2 saturation of Hb

Question 5

Why is the steep portion of the sigmoidal dissociation curve advantageous?

Answer 5

Because if there is a reduction of PO2 at the level of the peripheral tissue this will induce a reduction of PO2 at the level of the venous system and this means there is much less hemoglobin bound to oxygen which is important for unbinding oxygen

Question 6

What does the steep portion of the sigmoidal dissociation curve suggest?

Answer 6

That the changes in the curve are due to compounds produced in the tissues like pH and temperature that enhance unloading

Question 7

What does the steepest portion of the sigmoidal dissociation curve suggest?

Answer 7

The the decreased PO2 is due to increased metabolic rate using a lot of oxygen and ensures that hemoglobin will release oxygen to the periphery