Q. During inspiration

 1319  222 Breathing and Exchange of Gases Report Error

Solution:

• Inspiration is initiated by the contraction of diaphragm which increases the volume of thoracic chamber in the anterior-posterior axis. • During inspiration diaphragm contract and become flat.
• The contraction of external inter-coast al muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorsoventral axis. The overall increase in the thoracic volume causes a similar increase in pulmonary volume
• An increase in pulmonary volume decreases the intrapulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs, i.e. inspiration.