In the tissues, high concentrations of carbon dioxidea)increases the a...
Increase in the CO2 content of the blood decreases the pH of the blood. This decreases the affinity of O2 with Hb. This is called Bohr effect and is closely related to the fact that deoxygenated Hb binds hydrogen ions more actively than does the Hb. This facilitates gaseous exchange because more O2 is released in the tissues where the amount of CO2 is more due to metabolic activity. At the same time, more O2 is taken up by the lungs or gills when the amount of CO2 is low.
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In the tissues, high concentrations of carbon dioxidea)increases the a...
Carbon dioxide is a waste product produced by cells during cellular respiration. It needs to be removed from the tissues and transported to the lungs for elimination. One of the ways carbon dioxide is transported in the blood is by binding to hemoglobin, a protein found in red blood cells. Hemoglobin can also bind to oxygen and hydrogen ions.
The concentration of carbon dioxide in the tissues is higher than in the lungs, creating a concentration gradient that favors the diffusion of carbon dioxide out of the cells and into the blood. When carbon dioxide enters the blood, it reacts with water to form carbonic acid (H2CO3). This reaction is catalyzed by the enzyme carbonic anhydrase.
Now, let's understand the effect of high concentrations of carbon dioxide on the affinity of hemoglobin to oxygen and hydrogen ions:
- Affinity of Hemoglobin to Oxygen:
When carbon dioxide binds to hemoglobin, it causes a conformational change in the protein, resulting in a decrease in the affinity of hemoglobin for oxygen. This is known as the Bohr effect. In other words, high concentrations of carbon dioxide in the tissues lead to a decreased ability of hemoglobin to bind and carry oxygen. This is beneficial because it allows for the efficient unloading of oxygen in tissues that have a high metabolic demand.
- Affinity of Hemoglobin to Hydrogen Ions:
The formation of carbonic acid (H2CO3) from carbon dioxide and water results in the release of hydrogen ions (H+). These hydrogen ions can bind to hemoglobin, further decreasing its affinity for oxygen. This is known as the Haldane effect. Therefore, high concentrations of carbon dioxide in the tissues also increase the affinity of hemoglobin for hydrogen ions.
As a result, high concentrations of carbon dioxide in the tissues decrease the affinity of hemoglobin to oxygen but increase its affinity to hydrogen ions. This allows for the efficient removal of carbon dioxide from the tissues and its transport to the lungs for elimination. In the lungs, where the concentration of carbon dioxide is lower, the reverse reactions occur. Carbonic acid dissociates into carbon dioxide and water, and hydrogen ions are released from hemoglobin. This promotes the uptake of oxygen by hemoglobin, facilitating its transport to the tissues.
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