Read the following statements : i. Every 100 ml of deoxygenated blood ...
20 – 25% of CO2 is transported to the alveoli as carbamino-haemoglobin.
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Read the following statements : i. Every 100 ml of deoxygenated blood ...
CO2 Transport in Blood
i) Every 100 ml of deoxygenated blood delivers about 4 ml of CO2 to the alveoli.
ii) 30% - 40% of CO2 is transported to the alveoli as carbamino-hemoglobin.
iii) At the respiratory surface, CO2 diffuses from venous blood into alveolar spaces.
CO2 is produced as a waste product during cellular respiration and needs to be transported from the tissues to the lungs for elimination. The majority of CO2 is transported in the blood in three forms:
1. Dissolved CO2: A small portion of CO2 (about 5-10%) dissolves directly in the blood plasma.
2. Carbamino Compounds: CO2 can combine with amino groups of amino acids in the blood, forming carbamino compounds. This accounts for about 5-10% of CO2 transport.
3. Bicarbonate (HCO3-) ions: The most significant form of CO2 transport is in the form of bicarbonate ions. Carbon dioxide reacts with water in the red blood cells, forming carbonic acid (H2CO3), which dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). The bicarbonate ions are then transported out of the red blood cells into the plasma, while chloride ions (Cl-) move into the red blood cells to maintain electrochemical balance.
CO2 Transport to the Alveoli
i) Every 100 ml of deoxygenated blood delivers about 4 ml of CO2 to the alveoli: This statement is correct because as blood reaches the alveoli, CO2 diffuses from the blood into the alveolar spaces due to the concentration gradient. This allows for the removal of CO2 from the body during exhalation.
ii) 30% - 40% of CO2 is transported to the alveoli as carbamino-hemoglobin: This statement is correct. A portion of CO2 combines with hemoglobin to form carbamino-hemoglobin, which is then transported to the alveoli. This form of CO2 transport is reversible, meaning CO2 can dissociate from carbamino-hemoglobin and be released into the alveoli for expiration.
iii) At the respiratory surface, CO2 diffuses from venous blood into alveolar spaces: This statement is also correct. The respiratory surface, which consists of the alveoli, allows for the exchange of gases between the blood and the air. In this case, CO2 diffuses from the venous blood into the alveolar spaces, where it can then be exhaled.
Overall, statements i) and iii) are correct, while statement ii) provides additional information about one of the forms of CO2 transport. Therefore, the correct answer is option 'C' - only i) and iii) are correct.
Read the following statements : i. Every 100 ml of deoxygenated blood ...
The option 2 is incorrect because only 20-25% Co2 is transported to alveoli as carbaminohemoglobin. rest of the statement are true!
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