Mechanism of Breathing Inspiration and Expiration


 
 
Concept Explanation
 

Mechanism of Breathing Inspiration and Expiration

Mechanism of Breathing: Breathing is a physical process that involves intercostal muscles which lies between the ribs and the diaphragm and helps in breathing.

Inhaling: During inhaling, the intercostals muscles contract, the ribs are pushed upward and outward and the diaphragm contracts and moves downward. This upward and outward movement of the ribs and the descending movement of the diaphragm add to the space in the chest cavity. This increases the volume of the air-tight chest cavity and creates pressure inside the lungs. Air rushes from outside through the trachea to the air sacs and alveoli.

Exhaling: During exhaling, the intercostals muscles relax and simultaneously two movements takes place, i.e., the ribs move downward and inward, the diaphragm relaxes and moves upward to take up its original position. The downward and inner movement of the diaphragm reduce the space in the chest cavity. The capacity of the chest becomes smaller and the air rushes out of the lungs. The lungs get vacant and then contracts. This happens because the exhaled air contains carbon dioxide and carbon dioxide turns lime water milky. Hence, this activity shows that we exhale carbon dioxide during breathing.

Take one mirror and exhale air from your mouth on a mirror. We see some moisture on the mirror. This shows that the exhaled air contains water vapours which condense on the mirror to form tiny water droplets

Sample Questions
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Question : 1

Expulsion of the air from the lungs is called ________________ .

Right Option : C
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Question : 2

During exhalation ,size of chest cavity _________________

Right Option : B
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Question : 3

Exhaling is the downward and inner movement of the diaphragm reduce the space in the chest cavity. The capacity of the chest becomes smaller and the air rushes out of the ______________ .

Right Option : A
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