Mechanics of Breathing

Events of Respiration  Pulmonary ventilation – moving air in and out of the lungs  External respiration – gas exchange between pulmonary blood and alveoli  Respiratory gas transport – transport of oxygen and carbon dioxide via the bloodstream  Internal respiration – gas exchange between blood and tissue cells in bodies capillaries

Pleural lining Visceral pleura – Covers the surface of the lungs Parietal pleura – Covers the inner surface of the thoracic cavity Pleural fluid – Fluid separating two layers – Allows lungs to slide easily past thoracic walls – Does not allow lungs to separate from thoracic walls

Mechanics of Breathing (Pulmonary Ventilation)  Completely mechanical process  Depends on volume changes in the thoracic cavity  Boyle’s Law: Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure  Two phases  Inspiration – flow of air into lung  Expiration – air leaving lung Not these kind……..

Muscles involved in Inspiration Diaphragm – The muscle at the base of the ribcage contracts Intercostal muscles- Muscles between the ribs contract This process increases the volume of the thoracic cavity

Exhalation / Expiration