Most of the carbon dioxide produced by tissues is carried back to the lungs asa)bicarbonate ionsb)reduced haemoglobinc)carbaminohaemoglobind)a gas dissolved in plasmaCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

Most of the carbon dioxide produced by tissues is carried back to the lungs as .these are three ways carbon dioxide is carried in the blood stream from the peripheral tissues back to the lungs 1) as a dissolved gas 2) as bicarbonate 3) bound to hemoglobin ( and other proteins) as a carbaminohemoglobin

Answer

There are three ways carbon dioxide is carried in the bloodstream from the peripheral tissues back to the lungs: (1) as a dissolved gas, (2) as bicarbonate, and (3) bound to hemoglobin (and other proteins) as carbaminohemoglobin. As carbon dioxide diffuses from peripheral tissues into the bloodstream, approximately 10% of it remains dissolved in the plasma, or the extracellular fluid matrix of the blood, to a partial pressure of about 45 mmHg.

[2]

The majority of the carbon dioxide that diffuses through the capillaries and, ultimately, into the red blood cells combines with water in a chemical reaction catalyzed by the enzyme carbonic anhydrase to form carbonic acid. Carbonic acid almost immediately dissociates into a proton and a bicarbonate anion (HCO3-). Thus, bicarbonate is the principal means by which carbon dioxide is transported throughout the bloodstream according to the equation CO2 + H2O --> H2CO3 --> H+ + HCO3-.

Answer

The majority of carbon dioxide molecules (85 percent) are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. Carbonic anhydrase (CA) within the red blood cells quickly converts the carbon dioxide into carbonic acid (H2CO3). Carbonic acid is an unstable intermediate molecule that immediately dissociates into bicarbonate ions (HCO−3)(HCO3−) and hydrogen (H+) ions. Since carbon dioxide is quickly converted into bicarbonate ions, this reaction allows for the continued uptake of carbon dioxide into the blood down its concentration gradient.

Answer

Transport of Carbon Dioxide in the Body

Carbon dioxide is produced by tissues as a byproduct of cellular respiration. It needs to be transported back to the lungs for elimination. The majority of carbon dioxide is transported in the blood in the following ways:

Bicarbonate ions
- The enzyme carbonic anhydrase in red blood cells catalyzes the reaction between carbon dioxide and water to form carbonic acid.
- Carbonic acid dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+).
- Bicarbonate ions are transported in the plasma to the lungs.

Reduced haemoglobin
- Some carbon dioxide binds directly to the globin part of hemoglobin in red blood cells.
- This forms carbaminohaemoglobin, which is a reversible reaction.
- Reduced haemoglobin carries a small percentage of carbon dioxide back to the lungs.

Carbaminohaemoglobin
- Carbaminohaemoglobin is formed when carbon dioxide binds to the amino groups of hemoglobin.
- This form of carbon dioxide transport accounts for a small portion of the total carbon dioxide in the blood.

Therefore, the majority of carbon dioxide produced by tissues is carried back to the lungs as bicarbonate ions, making this the most important mechanism for carbon dioxide transport in the body.

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