Physiology 1 Flashcards
Internal mechanisms which consume O2 and produces CO2
Internal respiration
Exchange of O2 and CO2 between the external environment and body cells
External respiration
4 steps of external respiration?
- Ventilation between atmosphere and alveoli
- Exchange of gases between alveoli and blood
- Transport of gas from alveoli to tissues
- Exchange of gases between blood and tissues
Boyle’s law states?
At any constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas
As the volume of a gas increases….
the pressure exerted by the gas decreases
Describe air flow.
Down a pressure gradient from a region of high pressure to a region of low pressure
What must happen for air to flow into the lungs during inspiration?
Intra-alevolar pressure must become less than alveolar pressure
When is intra-alveolar pressure the same as atmospheric pressure?
Before inspiration
During inspiration the thorax and lungs…
Expand
This increases volume, thus decreasing pressure
Allowing air to flow into the lungs down a pressure gradient
Name 2 forces that hold the thoracic wall and lungs together.
Intrapleural fluid cohesiveness
Negative intrapleural pressure
Define intrapleral fluid cohesiveness.
The water molecules in the intrapleural fluid are attracted to each other and resist being pulled apart, thus the pleural membranes stick together
Define negative intrapleural pressure.
The sub-atmospheric intrapleural pressure create a transmural pressure gradient across the lung wall and across the chest wall, thus the lungs expand out and the chest wall expands in
Transmural pressure gradient across lung wall =
Intra-alveolar pressure - intrapleural pressure
Transmural pressure gradient across throacic wall =
Atmospheric pressure - intrapleural pressure
Atmospheric pressure
760 mmHg
