Question

When the diaphragm contracts, the thoracic cavity. and you A) gets smaller; exhale B) gets larger; inhale C) gets smaller; inhale D) gets larger; exhale

Answer 1

Ans.

• Inspiration and expiration are the two key events involved in the process of pulmonary ventillation.
• During inspiration air enters the lungs while during the process of expiration air leaves the lungs.
• A respiration cycle is formed by the sequential occurance of inspiration and expiration.
• Normally, two muscle groups, diaphragm and external intercostal muscles are involved during the process of inspiration.
• Upon contraction, diaphragm moves below, in the direction of abdominal cavity and increses the size of thoracic cavity, creating more space for lungs.
• Contraction of external intercostal muscles causes movement of ribs upward and outward, thereby expanding the rib cage and increasing the thoracic cavity volume.
• Expansion of thorcic cavity results in stretching and expansion of lungs as well.
• This increased volume reduces intra-alveolar pressure and creates a pressure less than the pressure of atmosphere.
• As a result, air enters the lungs due to creation of pressure gradient.
• Thus, upon contraction of diaphragm, the thoracic cavity gets larger and you inhale, a process also called as breathing in.