what affects partial pressure?
temperature and the number of molecules present
Air is a mixture of ___ gases, each with its own _____ ______
what gases make up air?
N2 - 79.6
O2 - 21.2
CO2 - 0.004
H2O - 0.5
pressure difference/ resistance
pressure difference =
atmospheric pressure - alveolar pressure
what’s Boyle’s law?
P1V1 = P2V2
whats the process of inspiration?
- Diaphragm and ext. intercostals contract and chest expands
- “Pull” makes intrapleural pressure more subatmospheric
- Increases transpulmonary pressure
- Lungs expand
- Alveolar pressure subatmospheric
- Air flows into alveoli
whats the process of expiration?
- Diaphragm and ext. intercostals relax
- Intrapleural pressure less subatmospheric
- Decreases transpulmonary pressure
- Lungs recoil
- Alveolar pressure increases
- Air flows out
Expiration results from ……
passive recoil of lungs and ribcage
What happens if intrapleural pressure = atmospheric pressure?
This would happen if a hole was inserted in the chest, so that there was continuity between the outside and the intrapleural cavity.
what are Two determinants of lung compliance?
elasticity surface tension (ST) forces
what is Pulmonary Surfacant ?
mixture of lipids and proteins which is secreted by the epithelial type II cells into the alveolar space
what does pulmonary steps?
Lowers surface tension at air-liquid interface in alveoli