Intrapleural and Intrapulmonary Pressure

Intrapleural Pressure:

• The pressure between the parietal and the viceral pleural membranes 
• should be 4 mmHg less than the pressure in the alveoli 
• Acts like a suction to keep the lungs inflated
• Always negative- which is caused by the elascity of the lungs and thoracic wall and the surface tension 
• Produces subatmospheric pressure in the intrapleural space 

Intrapulmonary Pressure:

• The pressure found in the alveoli of the lungs 
• should be equal to the atmospheric pressure 
• Atmospheric pressure doesn't change
• when you inhale or exhale, the pressure should fall less or more than the atmospheric pressue 
• Increase in lung volume during inspiration decreases intrapulmonary pressure to subatmospheric levels and allows for air to go in 
• Decrease in lung volume during expiration increases intrapulmonary pressure above atmospheric levels which expells out air