Pulmonary Physiology: Ventilation Flashcards
Is CO2 a large contributor of partial pressure to atmospheric air?
No!
What is PACO2 (alveoli)?
40 mmHg
What is PAO2 (alveoli)?
104 mmHg
What is PvO2 (venous)?
40 mmHg
What is PvCO2 (venous)?
46 mmHg
What is PaO2 (arterial)?
100 mmHg
What is PaCO2 (arterial)?
40 mmHg
Why is arterial PO2 4 mmHg less than alveolar PO2?
Some blood from the bronchial veins drains into the pulmonary veins, diluting the blood slightly.
What are the PO2 and PCO2 in cells?
PO2 is 40 mmHg and PCO2 is 46mmHg (same as venous blood!)
Are the partial pressures of gases in the body at steady state, or equilibrium?
steady state
How is minute ventilation calculated? What are the units?
rate x tidal volume = mL/min
What is the anatomic dead space? What is an average anatomic dead space volume?
The inhaled air that does not make it to the respiratory zones of the lungs. Avg is around 150 mL
The Fowler washout measures the anatomic dead space by monitoring ___ levels in the exhaled air after an initial inhalation of pure oxygen.
nitrogen
What is alveolar dead space? Is it normal?
Alveoli that are ventilated but not perfused - so no gas exchange happens. Only pathological.
When ventilation fails, PACO2 will increase, therefore so will ______ PCO2.
arterial
How does the Poiseulle equation apply to ventilation?
Flow is proportional to the 4th power of the radius of the airway
Turbulent flow requires ______ (more or less) pressure to move air while laminar flow requires ______ pressure to move the air.
turbulent needs more pressure, laminar needs less
Inspired air flows to terminal bronchioles down the pressure gradient, while the final movement of air into the alveoli occurs by ________.
diffusion
Explain why small airways have a total lower resistance than large airways despite being individually much smaller.
They are in parallel, and their total resistance equals the sum of the reciprocals of each individual small airway.
Sympathetic (beta-2) stimulation results in _________.
bronchodilation
What is functional residual capacity?
Expiratory reserve volume + residual volume. Its the air that is leftover in the lungs after a normal exhale.
What is vital capacity?
Expiratory reserve volume + inspiratory capacity. Its as much air as you can possibly inhale at once after exhaling really hard and inhaling really hard.
How is residual volume measured?
Helium dilution method: A person inhales helium from a tank with known volume and helium concentration, then the concentration of helium in the tank is measured and the volume of the lungs is calculated using C1V1 = C2V2
The lungs’ tendency to collapse is due to two things. What are they?
Alveolar surface tension - 2/3
Elastic recoil - 1/3
