Question

During which of the following processes the diaphragm moves down?
A) Inspiration
B) Expiration
C) Coughing
D) None of the above

Answer 1

Diaphragm is a muscular sheet-like structure present at the bottom of the thoracic cavity. It is an arch-shaped structure that separates the chest from the abdomen. The contraction of the diaphragm helps in pulling the air inside the lungs.

Complete answer:
Respiration is the process in which the air is taken in by the process of inhalation and the air is expelled out of the lungs by the process of expiration. The lungs are the chief organs for respiration. The lungs are present in the chest cavity. At the bottom of the lungs is the present diaphragm. The diaphragm is the arch-shaped muscle which is the principal muscle for respiration. It expands and contracts so as to increase the volume of the chest cavity so that respiration can take place.

During inspiration the diaphragm contracts. The contraction of the diaphragm pulls it down. This increases the volume of the thoracic cavity. This lowers the internal pressure and causes inhalation.

During expiration, the diaphragm relaxes as a result of which the diaphragm is pulled upward. This reduces the chest volume and the increase in pressure leads to exhalation of air.

The diaphragm is also important in expulsive actions like coughing. The diaphragm contracts during the expiratory phase of coughing. This can lead to pain in the ribs and diaphragm.

Therefore the correct answer is option ‘A’.

Note: The inspiration and expiration is brought about by the elastic property of the diaphragm. The intercostal muscles present in between the ribs are the other muscles that help in increasing the thoracic volume. Trauma, severe coughing and twisting movement can lead to pain in the diaphragm and intercostal muscles.