2 Breathing Mechanics Flashcards
What does Boyle’s law dictate?
Pressure exerted by gas is inversely proportional to its volume. ( P proportional to 1/V)
What is dalton’s law?
Total pressure of a gas mixture is the sum of the pressures of all individual gases (duh)
What is charles’ law?
Volume of a gas is proportional to temperature.
V proportional T
What is Henry’s law?
Amount of gas dissolved in a liquid depends on its solubility & pressure
What is inflammation of the pleura called?
Pleurisy
What do pleura do?
effectively stick the lungs to the ribs. This way the elastic recoil of the chess wall keeps the lung stretched open.
What muscles are involved in inspiration?
External intercostal muscles
diaphragm
Sternocleidomastoids
Scalenes
What muscles are involved in expiration?
Its passive at rest
But under heavy respiratory load the internal intercostal muscles & abdominal muscles are used.
What abnormal action occurs during asthma?
Over-constriction of the bronchial smooth muscle
What are the 3 relevant pressures in breathing?
Intra-thoracic pressure (Alveolar) (Pa)
Intra-pleural pressure (Pip)
Transpulmonary pressure (Pt)
What is intra-thoracic (alveolar) pressure?
Pa:
Pressure inside the thoracic cavity (lungs).
-ve or +ve compared to atmospheric pressure
What is intra-pleural pressure?
Pip:
Pressure inside pleural cavity.
Always -ve
What is transpulmonary pressure?
Pt:
alveolar pressure - intra-pleural pressure.
Always +ve because Pip is always -ve.
Is Alveolar pressure +ve or -ve?
Either as compared to atmospheric pressure
Is intra-pleural pressure -ve or +ve?
Always -ve
How is transpulmonary pressure determined?
Pt = Pa - Pip
What is the measurment of pressure?
mm Hg
‘millimetres of mercury’
How does alveolar pressure change?
During inspiration it decreases then returns to normal
During expiration it increases then returns to normal
How does intrapleural pressure change?
It decreases during inspiration
Returns to normal during expiration
What effects bulk flow of air between atmosphere & alveoli?
Proportional to differnce between atmospheric & alveolar pressure.
Inversely proportional to airway resistance.
Equation for bulk flow of air?
F = (Patm - Pa)/R
When does Patm = Pa?
Between breaths at the end of unforced expiration
What factor determines how much air flows into the lungs?
- Airway resistance
- Pressure difference between atmosphere & alveoli
