Question

What is the oxyhemoglobin dissociation curve, and what factors affect the curve to shift right or left. Additionally, explain what type of effect stored (banked) blood have on the oxyhemoglobin dissociation curve.

please use more than 350 words

Answer 1

Oxyglobin dissociation curve is a curve that mathemaically equates the percentage saturation of hemoglobin with partial pressure of oxygen in blood. It describes the non linear tendency of oxygen binding to hemoglobin. The curve is sigmoid in shape.

The reason for the non-linearity of the curve is the priciple of co-operativity- the binding of oxygen to one of the sites on the hemoglobin molecule increases the affinity of the other sites for oxygen. Each hemoglobin molecule binds to 4 oxygen molecules.This causes the sigmoid shape of the curve.The same principle applies in reverse as well. Unbinding of oxygen from one of the sites decreases the affinity of the other sites for oxygen

Coditions that cause increased binding of oxygen to hemoglobin shifts this curve to the left causing tight binding while those conditions that decrease the affinity of hemoglobin for oxygen shift the curve to the right causing increased unloading of oxygen. This helps in unloading oxygen in the tissues while increasing the binding while passing through the alveolar capillaries. There is 4 stage loading and unloading. Compared to this, the myoglobin curve has hyperbolic shape which reflects a one stage loading and unloading

Causes of right shift of ODC:

• Acidosis
• Hyperthermia
• Hypercarbia ( the increased levels in tissues help in unloading of oxygen)
• Increased 2,3-DPG
• High altitude
• Isoflurane - anesthesia drug

Causes of shift of ODC to left include:

• Alkalosis
• Hypothermia
• Hypocarbia
• Reduced 2,3- DPG (situations like banked blood)
• Fetal hemoglobin ( the tighter binding by fetal hemoglobin aids in the transfer of oxygen across placenta)
• carboxyhemoglobin- higher affinity

Banked blood- There is depletion of 2,3 DPG in banked blood. Hence once this blood is transfused, it causes a temporary shift of te ODC curve to the left, making less oxygen available to the tissues. However after 24 hours, the curve returns to normal