SM_150a: Mechanics I

Question 1

What is the function of a spirometer?

Answer 1

Measures the volume of air inspired or expired

Question 2

Volume ______ as a patient inspires

Answer 2

Volume increases as a patient inspires

Question 3

Volume ______ as a patient expires

Answer 3

Volume decreases as a patient expires

Question 4

What is residual volume?

Answer 4

The volume of air left after expiration

Question 5

Inspiratory capacity = _______ + _______

Answer 5

Inspiratory capacity = tidal volume + inspiratory reserve volume

Question 6

Vital capacity = ________ + ________ + ________

Answer 6

Vital capacity = tidal volume + inspiratory reserve volume + expiratory reserve volume

Question 7

Total lung capacity = ________ + ________

Answer 7

Total lung capacity = inspiratory capacity + functional residual capacity

Question 8

Functional residual capacity = ________ + ________

Answer 8

Functional residual capacity = expiratory reserve volume + residual volume

Question 9

Normal tidal volume is ________

Answer 9

Normal tidal volume is 500 mL

Question 10

Normal values for a female 20-30 years old

RV:

FRC:

VC:

TLC:

Answer 10

Normal values for a female 20-30 years old

RV: 1000 mL

FRC: 1800 mL

VC: 3200 mL

TLC: 4300 mL

Question 11

Normal values for a male 20-30 years old

RV:

FRC:

VC:

TLC:

Answer 11

Normal values for a male 20-30 years old

RV: 1200 mL

FRC: 2400 mL

VC: 4800 mL

TLC: 6000 mL

Question 12

What are the determinants of lung volume?

Answer 12

• Body size (primarily)
• Age
• Gender
• Race

Question 13

What is the equation for lung volume dilution measurement?

Answer 13

[He]_initial * V_spir = [He]_final * (Vol_spir + Vol_lung)

Question 14

What are the assumptions of the Ideal Gas Law?

Answer 14

Assumes molecules

• Have negligible volume
• Are in rapid random motion
• Are independent of each other
• Energy is conserved during collisions

Question 15

What is the Ideal Gas Law?

Answer 15

PV = nRT

If n, R, and T are constant, then P and V are inversely related

Question 16

What is pressure?

Answer 16

Force exerted per unit area

Question 17

What is partial pressure?

Answer 17

The pressure exerted by each component in a mixture of gases

(independent of pressures exerted by other cases in the mixture)

Question 18

What is Dalton’s Law of Partial Pressures?

Answer 18

P_total = P₁ + P₂ + P₃ + … P_n

Question 19

In dry room air, barometric pressure P_B is ______

Answer 19

In dry room air, barometric pressure is 760 mmHg

PO₂: 20.9% (159 mmHg)

PN₂: 78% (594 mmHg)

PCO₂: << 1% (0.23 mmHg)

Question 20

What is the solution to the fact that P_B and the pressure of its constituent gases vary as ambient pressure changes?

Why?

Answer 20

Using fractional gas concentrations

Fractional concentrations are independent P_B

Question 21

What is the formula for fractional concentration of a gas?

Answer 21

F_g = P_g / P_total

Question 22

Fractional concentrations are expressed as though ________ is NOT present

How?

Answer 22

Fractional concentrations are expressed as though PH₂O is NOT present

water vapor pressure is subtracted from total pressure, F_g = P_g / (P_B - PH₂O)

Question 23

Inspired air is _____ in the airways

Answer 23

Inspired air is warmed and humidifed in the airways

(air in trachea is saturated w/ water vapor, water vapor pressure varies w/ temperature)

Question 24

Answer 24

Question 25

What is STDP?

Answer 25

Standard temperature (0° C) and pressure (1 atm), dry (no water vapor)

Question 26

What is BTPS?

Answer 26

Body temperature (normal = 37 °C) and pressure (1 atm), saturated w/ water vapor

Question 27

What is ATPS?

Answer 27

Ambient temperature and pressure (environmental temperature and pressure), saturated w/ water vapor

Question 28

What is the formula for Henry’s Law?

Answer 28

C_{g, dissolved} = P_g * K

C_{g, dissolved} is the concentration dissolved

K is the solubility coefficient and is unique to solute gas, solvent, and temperature

Question 29

What does Henry’s Law state?

Answer 29

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

Question 30

How do you calculate the partial pressure in a liquid not in contact w/ a gas?

Answer 30

Measure dissolved concentration of gas and then use Henry’s Law to calculate partial pressure

Question 31

Gases diffuse down a ____________, not necessarily down a __________

Answer 31

Gases diffuse down a partial pressure gradient, not necessarily a concentration gradient