Question

What is the oxygen dissociation curve? List the factors which result in causing this curve.

Answer 1

Hemoglobin is the major carrier of oxygen in the bloodstream. Each molecule of haemoglobin can transport four oxygen molecules. These oxygen molecules attach to the heme prosthetic group's iron. Hemoglobin possesses the unbound structure when there is no bound oxygen or carbon dioxide (shape). The binding of the first oxygen molecule causes a change in hemoglobin's structure, which improves its capacity to bind the next three oxygen molecules. The pH of the blood changes when dissolved carbon dioxide is present; this produces another change in hemoglobin's structure, which improves its capacity to bind carbon dioxide while decreasing its ability to bind oxygen.

Complete answer:
Several factors influence the strength with which oxygen binds to haemoglobin. The oxyhemoglobin dissociation curve is shifted or reshaped by several variables. A rightward shift implies that the haemoglobin under investigation has a lower oxygen affinity. This makes it more difficult for haemoglobin to bind to oxygen (a greater partial pressure of oxygen is required to attain the same oxygen saturation), but also makes it simpler for haemoglobin to release oxygen attached to it. When oxygen is most needed, such as during exercise or hemorrhagic shock, the consequence of this rightward shift of the curve raises the partial pressure of oxygen in the tissues. There are several important factors that affect the affinity of haemoglobin to oxygen as therefore affect the oxygen-hemoglobin dissociation curve. These factors include the
(1) pH
(2) temperature
(3) carbon dioxide
(4) 2,3-BPG and
(5) carbon monoxide. By increasing the hydrogen ion concentration (and therefore the pH), the temperature, the carbon dioxide concentration or the amount of 2,3-BPG present in the red blood cell, we ultimately decrease the affinity of haemoglobin to oxygen and therefore shift the curve to the right side. This allows us to unload more oxygen to our tissues.

Note:
Because foetal haemoglobin (HbF) differs structurally from adult haemoglobin (HbA), HbF has a greater affinity for oxygen than HbA. Two alpha and two gamma chains make up HbF, while two alpha and two beta chains make up HbA. Because of these anatomical changes, the prenatal dissociation curve is tilted to the left compared to the typical adult curve.