Physiology of Respiration

 

Mechanism of Breathing

 

1 Atmospheric pressure = 760mmHg

Pulmonary ventilation has three phase-

1. Inspiration

2. Expiration

3. Pause

Thoracic cavity expands

Lung volume increases

All pressure inside is decreased

Greater pressure outside cause flow of air into the lung.

When thoracic cavity contract

Lung volume decreases

All pressure inside is increased

Air flow out

Muscular Control of Breathing

Main muscles of respiration are diaphragm and intercostal muscles (muscle between the ribs). The diaphragm is the principle muscle of breathing.

Abdominal muscles are also important in mechanism of breathing.

Abdominal muscle can help increase and decrease strength of inspiration and expiration.