GMS6402 STUDY GUIDE 2025/2026 QUESTIONS AND
SOLUTIONS GRADED A+ TIP
✔✔what does the pleural pressure have to get to before the airways start to open - ✔✔-
8 cm H2O
✔✔what is hysteresis - ✔✔the difference in the inflation and deflation lines of the
pressure volume curve
exists bc it takes more pressure to open closed airway than to keep open airway from
closing
✔✔what is the formula for work - ✔✔force x distance
delta P = force
delta V = distance
✔✔in the pressure volume curve, what does line AEC mean - ✔✔compliance
✔✔in the pressure volume curve, what does ABCDA mean - ✔✔total work of breathing
✔✔pressure volume curve for restrictive diseases - ✔✔flatter AEC (compliance) line,
also means smaller delta V/delta P
much more work done (ABCDA)
✔✔what point in the pressure volume curve is not a physiological point - ✔✔D
✔✔pressure volume curve for obstructive diseases - ✔✔less work required to inspire
work IS required to expire, goes to left of normal AD line
line AEC is higher, higher compliance
✔✔what is impaired in restrictive diseases - ✔✔lung inflation
✔✔what is impaired in obstructive diseases - ✔✔lung deflation
✔✔what determines lung compliance - ✔✔elastic forces of the lungs
✔✔what are the two parts of the elastic forces - ✔✔-elastic forces of lung tissues
(elastin and collagen), contribute 1/3 to elastic recoil
-elastic forces from surface tension at air:water interface, contributes 2/3 to elastic recoil
,✔✔what SHOULD the surface tension be in the alveoli? what is it actually? - ✔✔should
be 50-70 dynes
actually is 5-10 dynes
due to surfactant, reduces ST by 50-90%
✔✔how does surfactant work to decrease surface tension - ✔✔breaks up rigid structure
of water molecules
changes from air:water to air:oil
✔✔what cell produces surfactant in the alveoli - ✔✔type II epithelial cells, is 10% of
cells
✔✔what is the active agent in surfactant - ✔✔dipalmitoylphosphatidylcholine
✔✔what is LaPlace's Law - ✔✔the pressure required to keep alveoli open
P= 2T / r
T=surface tension
r=radius
says that 2x as much pressure is required to keep smaller alveoli open compared to
larger ones
✔✔what happens to compliance without surfactant - ✔✔lung compliance is decreased,
restrictive disease
common in premie babies
✔✔@ what gestational age does surfactant production start - ✔✔24 weeks
called Acute Respiratory Disorder Syndrome (ARDS)
treatment: nebulizer, positive pressure ventilator
✔✔what is minute ventilation - ✔✔the amount of air we breathe in and out each minute
tidal volume x respiratory rate
normal is around 6000 mls/minute or 6L
, ✔✔what is alveolar ventilation - ✔✔the amount of air that makes it into the alveolar
airways
(tidal volume - anatomic dead space) x respiratory rate
usually around 4200 mls/minute or 4.2L
anatomic dead space is usually around 150 mls
✔✔what % of the air we breathe in is available for gas exchange - ✔✔70%
✔✔what is Dalton's Law - ✔✔the total pressure of a gas mixture is the sum of the
individual pressures
✔✔what is the total pressure at sea level - ✔✔760 mm Hg or 1 atm
oxygen is 21% (160 mm Hg)
nitrogen is 79% (600 nm Hg)
✔✔what happens to the pressure of O2 as we move from the atm to the tissues - ✔✔it
drops
✔✔atmospheric oxygen pressure - ✔✔160 mm Hg
✔✔inspired O2 pressure - ✔✔150 mm Hg
✔✔alveolar O2 pressure - ✔✔100 mm Hg
✔✔arterial O2 (PaO2) pressure - ✔✔100 mm Hg
✔✔arterial CO2 (PaCO2) pressure - ✔✔40 mm Hg
✔✔for the alveolar gas equation, what is the vapor pressure of H2O? - ✔✔47, always
the same
✔✔what determines the arterial blood gas values - ✔✔tidal volume
✔✔what is the alveolar gas equation used for - ✔✔as a diagnostic tool to see if
ventilation is sufficient
✔✔what is the formula for P(Insp)O2 - ✔✔(760-47) x FIO2
✔✔what is the equation for PalvO2 - ✔✔P(insp)O2 - (PalvCO2/R)
SOLUTIONS GRADED A+ TIP
✔✔what does the pleural pressure have to get to before the airways start to open - ✔✔-
8 cm H2O
✔✔what is hysteresis - ✔✔the difference in the inflation and deflation lines of the
pressure volume curve
exists bc it takes more pressure to open closed airway than to keep open airway from
closing
✔✔what is the formula for work - ✔✔force x distance
delta P = force
delta V = distance
✔✔in the pressure volume curve, what does line AEC mean - ✔✔compliance
✔✔in the pressure volume curve, what does ABCDA mean - ✔✔total work of breathing
✔✔pressure volume curve for restrictive diseases - ✔✔flatter AEC (compliance) line,
also means smaller delta V/delta P
much more work done (ABCDA)
✔✔what point in the pressure volume curve is not a physiological point - ✔✔D
✔✔pressure volume curve for obstructive diseases - ✔✔less work required to inspire
work IS required to expire, goes to left of normal AD line
line AEC is higher, higher compliance
✔✔what is impaired in restrictive diseases - ✔✔lung inflation
✔✔what is impaired in obstructive diseases - ✔✔lung deflation
✔✔what determines lung compliance - ✔✔elastic forces of the lungs
✔✔what are the two parts of the elastic forces - ✔✔-elastic forces of lung tissues
(elastin and collagen), contribute 1/3 to elastic recoil
-elastic forces from surface tension at air:water interface, contributes 2/3 to elastic recoil
,✔✔what SHOULD the surface tension be in the alveoli? what is it actually? - ✔✔should
be 50-70 dynes
actually is 5-10 dynes
due to surfactant, reduces ST by 50-90%
✔✔how does surfactant work to decrease surface tension - ✔✔breaks up rigid structure
of water molecules
changes from air:water to air:oil
✔✔what cell produces surfactant in the alveoli - ✔✔type II epithelial cells, is 10% of
cells
✔✔what is the active agent in surfactant - ✔✔dipalmitoylphosphatidylcholine
✔✔what is LaPlace's Law - ✔✔the pressure required to keep alveoli open
P= 2T / r
T=surface tension
r=radius
says that 2x as much pressure is required to keep smaller alveoli open compared to
larger ones
✔✔what happens to compliance without surfactant - ✔✔lung compliance is decreased,
restrictive disease
common in premie babies
✔✔@ what gestational age does surfactant production start - ✔✔24 weeks
called Acute Respiratory Disorder Syndrome (ARDS)
treatment: nebulizer, positive pressure ventilator
✔✔what is minute ventilation - ✔✔the amount of air we breathe in and out each minute
tidal volume x respiratory rate
normal is around 6000 mls/minute or 6L
, ✔✔what is alveolar ventilation - ✔✔the amount of air that makes it into the alveolar
airways
(tidal volume - anatomic dead space) x respiratory rate
usually around 4200 mls/minute or 4.2L
anatomic dead space is usually around 150 mls
✔✔what % of the air we breathe in is available for gas exchange - ✔✔70%
✔✔what is Dalton's Law - ✔✔the total pressure of a gas mixture is the sum of the
individual pressures
✔✔what is the total pressure at sea level - ✔✔760 mm Hg or 1 atm
oxygen is 21% (160 mm Hg)
nitrogen is 79% (600 nm Hg)
✔✔what happens to the pressure of O2 as we move from the atm to the tissues - ✔✔it
drops
✔✔atmospheric oxygen pressure - ✔✔160 mm Hg
✔✔inspired O2 pressure - ✔✔150 mm Hg
✔✔alveolar O2 pressure - ✔✔100 mm Hg
✔✔arterial O2 (PaO2) pressure - ✔✔100 mm Hg
✔✔arterial CO2 (PaCO2) pressure - ✔✔40 mm Hg
✔✔for the alveolar gas equation, what is the vapor pressure of H2O? - ✔✔47, always
the same
✔✔what determines the arterial blood gas values - ✔✔tidal volume
✔✔what is the alveolar gas equation used for - ✔✔as a diagnostic tool to see if
ventilation is sufficient
✔✔what is the formula for P(Insp)O2 - ✔✔(760-47) x FIO2
✔✔what is the equation for PalvO2 - ✔✔P(insp)O2 - (PalvCO2/R)
