Question

18. Regarding the oxygen-hemoglobin dissociation curve, a patient suffering from a fever would have a hemoglobin saturation curve shifted to the of a normal hemoglobin curve as an increase in temperature causes affinity for oxygen. a. left // higher b. left // lower c. right // higher. d. right // lower. e. None of these—temperature does not affect hemoglobin’s affinity for oxygen.

Answer 1

18. Oxygen-haemoglobin dissociation curve is obtained when the partial pressure of oxygen (pO2) is plotted against percentage of haemoglobin saturation. In our body haemoglobin has affinity to binds with oxygen. Haemoglobin contains four haem molecules, and each haem molecule can combine with four oxygen molecule. Oxygen can bind with the iron ion of the haem molecule. So, in Oxygen-haemoglobin dissociation curve as the pO2 increases the % of haemoglobin saturation increases sigmoidally not linearly. This sigmoid curve represents the Oxygen-haemoglobin dissociation curve of the body.

In fever condition, the metabolism of the muscle and body increases. CO2 accumulation increases in the increased temperature condition. Due to increased temperature in fever the oxygen consumption of the body increases this will decreases pO2 level and enhances the lactate accumulation. This increased accumulation of lactate decreases the pH. in this condition the body cells need more oxygen and facilitate the delivery of oxygen to the tissue from the haemoglobin. So, the affinity of oxygen to haemoglobin in fever condition is lower to supply more oxygen to the body. The Oxygen-haemoglobin dissociation curve is shifted right than a normal hemoglobin curve, it signifies that the oxygen saturation of the haemoglobin is lower than the normal curve due to much offloading of oxygen. So, option D is correct, right shift of Oxygen-haemoglobin dissociation curve and lower oxygen affinity of haemoglobin in fever condition.

Option A is incorrect because, left shift of Oxygen-haemoglobin dissociation curve is happend when the body temperature drops below the 37°C. In this condition oxygen affinity to haemoglobin is higher. In fever condition the temperature of the body increases higher than the 37°C so, the shift should be in the right side.

Option B is also incorrect because, Oxygen-haemoglobin dissociation curve doesn't shifted left in fever condition. The oxygen affinity to haemoglobin should be lower in fever condition but shift should be in right side.

Option C is incorrect because, the oxygen affinity for haemoglobin should be lower in case of fever condition, so that the tissue get more oxygen and oxygenation of the muscles is increased. By lowering the oxygen affinity, body helps to deliver more oxygen to the tissue from the haemoglobin.