The mechanisms of breathing Flashcards
what is gas pressure measured in?
barometer
define partial pressure
the pressure exerted by a single gas in a mixture
define ventilation
the movement of gases in and out of lungs
what 3 factors impact the amount of ventilation?
- the respiratory pressures
- compliance (ease of inflation)
- airway resistance
what 2 things does ventilation consist of? which is active and which is passive?
- inspiration (always active)
- expiration (largely passive at rest)
explain inspiration
The diaphragm forces lungs downwards and external intercostals raise the rib cage.
Increasing the volume of the thoracic cavity, decreasing pressure.
explain expiration
Causes recoil of diaphragm and chest cavity.
This decrease in the volume of the thoracic cavity, increases the pressure.
what is the intrapulmonary/alveolar pressure?
Pressure inside the airways and alveoli
what is the intrapleural pressure?
pressure in the pleural cavity
what is the intrathoracic pressure?
Pressure in thoracic cavity.
what is the transpulmonary pressure?
Difference between the intrapulmonary and intrapleural pressures
define lung compliance
how easy it is to inflate the lungs
what 2 factors influence lung compliance?
elasticity and suface tension
what is the tidal volume?
Air that moves in and out during normal breathing.
what is the inspiratory reserve volume (IRV)?
max. air taken in after tidal volume
