Ambient air pressure =760 mm Hg ●= Density of air molecules xpiration Inspiration 63 mm H 758 mm Hg. 1.Contraction of ribs(internal intercostals) 1. Elevation of ribs(external intercostals) 2. Intrathoracic volume decreased 2. In trathoradic volume increased 3. Intrathoracic pressure rises 3. Intrathoracic pressure falls 4. Therefore, air flows out of airway 4. Therefore, air flows in to airway down its pressure gradient down its pressure gradient
Patterns of respiration ■ Eupnea(平静呼吸): inspiration is active, expiration is passive Abdominal breathing Thoracic breathing Forced breathing(用力呼吸): respiratory movement is greatly enhanced during physical exercise
Patterns of respiration ◼ Eupnea（平静呼吸）: inspiration is active, expiration is passive. – Abdominal breathing – Thoracic breathing ◼ Forced breathing （用力呼吸） : respiratory movement is greatly enhanced during physical exercise
Principles of pulmonary ventilation a Direct force of breathing Pressure gradient between atmosphere and lung a Original force of breathing Respiratory movement
Principles of pulmonary ventilation ◼ Direct force of breathing – Pressure gradient between atmosphere and lung ◼ Original force of breathing – Respiratory movement
Intrapulmonary pressure Alveolar pressure =The pressure of air inside the lung alveoli at Rest during Inspiration Atmospheric Atmospheric ressure pressure 60 mm Hg) (760 mm Hg) Intra-alveolar Intra-alveolar pressure pressure 760 mm Hg) (758 mm Hg) Diaphragm
Intrapulmonary pressure = Alveolar pressure =The pressure of air inside the lung alveoli
Trachea Inspiration Expiration Bronchi Alveolar pressure pressur (mm Hg) Right pleural Left pleural cavity 750 of air moved 500 250 Time(sec