Haemoglobin is an amazing molecule, as it allows vertebrates to transport gases
ID: 275430 • Letter: H
Question
Haemoglobin is an amazing molecule, as it allows vertebrates to transport gases from the environment to the tissues. To boot, blood changes its oxygen-binding characteristics in response to the animal’s external AND internal environment. How does this happen? What are the advantages of this “shape-shifting” ability? How does O2 affinity of Hb compare between mammals adapted to hypoxia and those in normoxia? How does it compare between sedentary and athletic species? Explain why. Some Antarctic fish lack haemoglobin completely. Their blood is composed of plasma and a few white blood cells. How are these fishes able to survive and succeed in their environment? Explain.
Explanation / Answer
The change in the physiological conditions leads to the change in the binding affinity of hemoglobin towards oxygen.For example, the increasing in temperature causes the decrease in the affinity of hemoglobin to bind with oxygen. Decrease in pH also lowers the oxygen biding affinity of hemoglobin.In this way any variation in the body internal environment or external environment, it leads to the change in the affinity of hemoglobin leads to the variation in the oxygen binding capacity. Advantage of shape shifting ability: Due to this shape shifting ability the human blood acclimatize according to the environment. During normal conditions the hemoglobin curve is sigmoid due to cooperative effect. But whenever there is variation in the physiological conditions like pH, temperature, or pressure, there is change in the oxygen binding capacity of the hemoglobin and hence the curve shifted towards left or right depending upon the increased or decreased affinity respectively. It is advantageous as it allow the cells to survive in the harsh conditions that may be oxygen lacking or flooding conditions. Mammals adapted to hypoxia: At hypoxic condition the affinity of the hemoglobin increased for oxygen to provide fast oxygen to the cells to oxygenate the tissues and minimize the tension due to oxygen difference in the pulmonary O2 and the sites of loading for survival. While in normal condition its simple allosteric biding of oxygen that is cooperative. The oxygen supply in athletes is faster as compared to the sedentary because the demand of oxygen in the muscle of athletes is much vigorous. But the rupture of RBC during weightlifting, running lead to the regeneration of RBC at a higher rate. Due to which the no. of younger cells is comparatively very high in athletes as compared to the sedentary. And the efficiency of younger RBCs is high towards oxygen binding. So the oxygen supply or binding capacity of hemoglobin for oxygen in new blood cells is higher. Antarctica fish also known as icefish completely lack Red blood cells and hemoglobin. But they survive because they absorbed so much dissolved oxygen from the ocean through their gills and extremely thin skin. Their thinner blood requires no extra effort to circulate. They have large veins and vessels in its body, and an enlarged heart. They carry very less blood approx 10% of a normal fish can carry. But the large veins allow the faster circulation of oxygen ensures that every tissue will get the adequate amount of oxygen.
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