Diffusion, gas exchange, metabolic rates Flashcards
What are the diffusion barriers between plasma and alveolar space?
Membrane of RBCs; vascular endothelium; fused basement membrane; alveolar epithelium; surfact on alveolar side
What is the relationship between solubility and diffusion?
Greater solubility enables greater rates of diffusion
Which gas has higher solubility: O2 or CO2?
CO2 has higher solubility, and thus higher rates of diffusion
How do changes in partial pressure enable gas exchange at the lungs?
Alveoli have higher P(O2) and lower P(CO2) than capillaries, enabling CO2 to enter alveoli, and O2 to enter capillaries
How do changes in partial pressure enable gas exchange at the tissues?
Alveoli have lower P(O2) and higher P(CO2) than capillaries, enabling O2 to enter alveoli, and CO2 to enter capillaries
What is the relation between O2 inspired and O2 used?
Volume of O2 inspired is exactly what body is using
What is the relation between CO2 expired and CO2 produced?
Volume of CO2 expired exactly what body is producing
How do partial pressures equilibriate?
Gas molecules move between air and liquid until equilibrium of partial pressures is reached
What do the movements of molecules depend on?
Temperature, pressure difference, and solubility
How does solubility affect concentration?
The more soluble a gas is, the higher the concentration at the same partial pressure
Why is rate of diffusion important?
Needs to be fast enough so gases in alveoli and blood equilibrate during passage of blood across alveolus; during max exercise, have significantly reduced time for efficient diffusion
What might impair diffusion?
Blood/ gas barrier thickening; lower partial pressure of inspired O2: e.g. altitude and disease
What is hypoxic pulmonary vasoconstriction?
A phenomenon that is responsible for matching ventilation and perfusion; vasoconstriction of pulmonary vessels diverts O2 to areas where it is needed when low O2 levels are detected
What are pathological limitations of diffusion?
Emphysema, fibrotic lung disease, pulmonary edema, asthma
How does emphysema affect ventilation?
Destruction of alveoli causes lowered SA and poor elastic recoil
