23 Questions
According to Fick’s Law, the rate of transfer through a sheet of tissue is proportional to which of the following?
Tissue area and the difference in partial pressure of gas
Which gas has the highest diffusion coefficient?
Helium
What is the primary driving force for net diffusion of molecules?
Pressure difference
What does the diffusion coefficient depend on?
Solubility and molecular weight
What is the range of thickness for diffusion across the respiratory membrane?
0.2-0.5
Which gas has the lowest diffusion coefficient?
Nitrogen
What does Fick’s Law state about the rate of transfer through a sheet of tissue?
Proportional to tissue area and the difference in partial pressure of gas
What is the primary factor affecting the rate of diffusion of molecules?
Surface area
What is the relationship between the diffusion coefficient and solubility?
Directly proportional
What is the primary driving force for diffusion of molecules?
Pressure difference
What factor is the diffusion coefficient inversely proportional to?
Molecular weight
What does the diffusion coefficient depend on?
Solubility and square root of molecular weight
What is the relationship between the partial pressures of nitrogen and oxygen in normal air at sea level?
The partial pressure of nitrogen is about 4 times higher than that of oxygen
For a given concentration, how does the partial pressure of carbon dioxide (CO2) relate to that of oxygen (O2) dissolved in water/tissue?
The partial pressure of CO2 is much higher than that of O2
In the alveolar air, what is the approximate concentration of oxygen (O2) compared to that in atmospheric air?
O2 concentration is lower in alveolar air than in atmospheric air
What is the primary factor affecting the rate of diffusion of molecules?
Solubility of the molecules
What determines the partial pressure of oxygen (PO2) and carbon dioxide (PCO2) in alveoli?
Ventilation-Perfusion Ratio (VA/Q)
In an upright individual, how do ventilation and perfusion (blood flow) change from the apex to the base of the lung?
Both ventilation and perfusion increase, with perfusion increasing faster
In the anatomic shunt model of ventilation-perfusion abnormalities, what happens to a portion of the cardiac output?
It bypasses the lung and mixes with oxygenated blood
What happens in the physiological shunt model of ventilation-perfusion abnormalities?
Ventilation goes to 0 in the affected lung region
What is the term for the combined effect of uneven ventilation and anatomic dead space resulting in wasted ventilation?
Physiological dead space
What is the functional residual capacity (FRC) of the lungs approximately?
About 1800 mL
What is the approximate amount of atmospheric air that reaches the alveoli?
About 500 mL
Test your knowledge of gas exchange with this quiz designed to cover topics such as Fick's Equation, diffusing capacity, oxygen diffusion from alveoli into the blood, and the distinction between perfusion limitation and diffusion limitation of gas transfer in the lung. Ideal for students studying respiratory physiology or related fields.
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