Respiratory physiology Flashcards
What factors does lung expansion depend on?
Transpulmonary pressure(Ptp) Compliance
What factors does lung compliance depend on?
Surface tension
Stretchability
What is transpulmonay pressure?
Alveolar pressure(Palv) - intrapleural pressure(Pip)
Describe inspiration
Contraction of the diaphragm Increased volume of the thoracic cavity Decreased intrapleural pressure Increased transpulmonary pressure Lungs expand Decrease alveolar pressure (Palv)
What is the main component of surfactant?
Phospholipids
What is the effect of surfactant?
Reduces surface tension
How does surfactant reduce surface tension?
Reduces cohesion between water molecules
What are pores of Kohn?
Interconnections between adjacent alveoli
Give an advantage of pores of Kohn?
Prevent alveoli collapsing if occluded, they can still receive air from adjacent alveoli
Give a disadvantage of pores of Kohn?
Allow rapid transmission of infection
What is Boyle’s law?
Pressure is inversely proportional to volume
What is Laplace’s law?
Pressure = 2 Surface Tension (T)/ radius (r)
Give the formular for flow
Flow = Change in pressure/ resistance
Where is the greatest airway resistance?
5th-7th division
What factors affect airway resistance?
1) * Tube Radius
2) Tube length
3) Interactions between gas molecules (similar to viscosity in the blood)
=> Poiseilles law
