Concept:Inhalation is the active phase of breathing where the diaphragm contracts and flattens, moving downward.
Explanation:During inhalation, the diaphragm moves down, not up.
The ribs move outward and upward to expand the chest cavity.
This expansion causes the lungs to expand and draw air in through the nostrils.
The movement “diaphragm moves up” happens only during exhalation, when the diaphragm relaxes.
Therefore, option 3 is incorrect as when human beings inhale oxygen during respiration then the diaphragm moves down.
Additional InformationMechanism of Respiration
During Inhalation
When we inhale oxygen from the air, it draws in through the nostrils into the nasal cavity.
From the nasal cavity, the air reaches our lungs and lungs are present in the chest cavity.
Then the diaphragm and muscles attached to the ribs contract due to increases in the volume inside the chest cavity.
Due to an increase in volume, the air pressure decreases inside the chest cavity and the air from outside rushes into the lungs.
In this way, the air sac or alveoli of the lungs get filled with air containing oxygen.
From the alveoli of the lungs, oxygen diffuses into the blood for carrying out respiration, and the waste product of respiration i.e. carbon dioxide diffuses from the blood into the alveoli of the lungs.
During Exhalation
When we exhale the air, the diaphragm and muscles attached to the ribs relax due to which our chest cavity contracts and become smaller.
This contraction movement of the chest cavity pushes out carbon dioxide from the lungs into the trachea followed by nostrils and then out of the body into the air.
Answer:Option C – Diaphragm moves up
