Question

Discuss about the process of inspiration.

Answer 1

• Normal breathing involves alternate inhalation or expiration and exhalation or expiration.
  
• It involves the following muscles-

1) The major muscle responsible for breathing (inhalation and exhalation) is the diaphragm'

• It is a dome-shaped thin muscle which separates the abdominal cavity and the thoracic cavity.
• At the time of inhalation, the diaphragm contracts which compresses the abdominal cavity and raises the ribs upward and outwards to expand the thoracic cavity.
• This expansion causes air to be drawn into the lungs.
• As the diaphragm relaxes, the thoracic cavity contracts and forces the air to move out of the lungs

2) The intercostal muscles are attached between the ribs and are helps in increasing and decreasing the width of the rib cage.

• The contraction of the external intercostal muscle fibres raises each rib toward the rib above and thus, raising the rib cage as well as assists in inhalation.
• The internal intercostal muscle fibres assist in lowering the rib cage and causes exhalation.
  
• During inspiration, the expansion of the thoracic cavity decreases the intra-alveolar pressure below the atmospheric pressure.