SM_150a: Mechanics I Flashcards
What is the function of a spirometer?
Measures the volume of air inspired or expired
Volume ______ as a patient inspires
Volume increases as a patient inspires
Volume ______ as a patient expires
Volume decreases as a patient expires
What is residual volume?
The volume of air left after expiration
Inspiratory capacity = _______ + _______
Inspiratory capacity = tidal volume + inspiratory reserve volume
Vital capacity = ________ + ________ + ________
Vital capacity = tidal volume + inspiratory reserve volume + expiratory reserve volume
Total lung capacity = ________ + ________
Total lung capacity = inspiratory capacity + functional residual capacity
Functional residual capacity = ________ + ________
Functional residual capacity = expiratory reserve volume + residual volume
Normal tidal volume is ________
Normal tidal volume is 500 mL
Normal values for a female 20-30 years old
RV:
FRC:
VC:
TLC:
Normal values for a female 20-30 years old
RV: 1000 mL
FRC: 1800 mL
VC: 3200 mL
TLC: 4300 mL
Normal values for a male 20-30 years old
RV:
FRC:
VC:
TLC:
Normal values for a male 20-30 years old
RV: 1200 mL
FRC: 2400 mL
VC: 4800 mL
TLC: 6000 mL
What are the determinants of lung volume?
- Body size (primarily)
- Age
- Gender
- Race
What is the equation for lung volume dilution measurement?
[He]initial * Vspir = [He]final * (Volspir + Vollung)
What are the assumptions of the Ideal Gas Law?
Assumes molecules
- Have negligible volume
- Are in rapid random motion
- Are independent of each other
- Energy is conserved during collisions
What is the Ideal Gas Law?
PV = nRT
If n, R, and T are constant, then P and V are inversely related
What is pressure?
Force exerted per unit area
What is partial pressure?
The pressure exerted by each component in a mixture of gases
(independent of pressures exerted by other cases in the mixture)
What is Dalton’s Law of Partial Pressures?
Ptotal = P1 + P2 + P3 + … Pn
In dry room air, barometric pressure PB is ______
In dry room air, barometric pressure is 760 mmHg
PO2: 20.9% (159 mmHg)
PN2: 78% (594 mmHg)
PCO2: << 1% (0.23 mmHg)
What is the solution to the fact that PB and the pressure of its constituent gases vary as ambient pressure changes?
Why?
Using fractional gas concentrations
Fractional concentrations are independent PB
What is the formula for fractional concentration of a gas?
Fg = Pg / Ptotal
Fractional concentrations are expressed as though ________ is NOT present
How?
Fractional concentrations are expressed as though PH2O is NOT present
water vapor pressure is subtracted from total pressure, Fg = Pg / (PB - PH2O)
Inspired air is _____ in the airways
Inspired air is warmed and humidifed in the airways
(air in trachea is saturated w/ water vapor, water vapor pressure varies w/ temperature)
What is STDP?
Standard temperature (0° C) and pressure (1 atm), dry (no water vapor)
What is BTPS?
Body temperature (normal = 37 °C) and pressure (1 atm), saturated w/ water vapor
What is ATPS?
Ambient temperature and pressure (environmental temperature and pressure), saturated w/ water vapor
What is the formula for Henry’s Law?
Cg, dissolved = Pg * K
Cg, dissolved is the concentration dissolved
K is the solubility coefficient and is unique to solute gas, solvent, and temperature
What does Henry’s Law state?
For a gas in contact w/ a liquid, the amount of gas that goes into solution is dependent on the partial pressure of the gas and the solubility of the gas in a liquid
How do you calculate the partial pressure in a liquid not in contact w/ a gas?
Measure dissolved concentration of gas and then use Henry’s Law to calculate partial pressure
Gases diffuse down a ____________, not necessarily down a __________
Gases diffuse down a partial pressure gradient, not necessarily a concentration gradient
