Assertion: the size of the chest cavity increases during inhalation. ...
Assertion: The size of the chest cavity increases during inhalation.
Reason: The lungs expand when we breathe in.
Option a: Both assertion and reason are true, and the reason is the correct explanation of the assertion.
Option b: Both assertion and reason are true, and the reason is not the correct explanation of the assertion.
Option c: Assertion is true, but the reason is false.
Option d: Assertion is false, but the reason is true.
Explanation:
Size of the Chest Cavity during Inhalation
During inhalation, the size of the chest cavity does indeed increase. When we breathe in, the diaphragm, which is a dome-shaped muscle located at the bottom of the chest cavity, contracts and moves downward. This movement of the diaphragm creates more space in the chest cavity. Additionally, the intercostal muscles, located between the ribs, contract and lift the ribcage up and out. This further expands the chest cavity. As a result, the lungs are able to expand and fill with air.
Expansion of the Lungs during Inhalation
The reason behind the increase in the size of the chest cavity during inhalation is the expansion of the lungs. When we breathe in, the lungs expand as a result of the increased space in the chest cavity. The expansion of the lungs allows them to fill with air, which is necessary for the exchange of oxygen and carbon dioxide.
Both Assertion and Reason are True
Both the assertion and the reason are true. The size of the chest cavity does increase during inhalation, and the lungs do expand when we breathe in.
Reason is Not the Correct Explanation of the Assertion
However, the reason provided does not correctly explain why the size of the chest cavity increases during inhalation. The reason states that the lungs expand when we breathe in, which is true, but it does not directly explain why the chest cavity size increases. The expansion of the lungs is a result of the increased space in the chest cavity due to the contraction of the diaphragm and the lifting of the ribcage by the intercostal muscles.
Conclusion
Therefore, the correct option is Option b: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
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