What is the primary function of the lungs?
convert angiotensin I to angiotensin II
filter pulmonary blood
gas exchange
remove carbon monoxide (CO)
During each cycle of normal resting ventilation, a volume of gas is moved into and out of the respiratory tract. This cyclical volume is called the:
residual volume (RV)
tidal volume (VT)
inspiratory reserve volume (IRV)
vital capacity (VC)
Which of the following pressures vary throughout the normal breathing cycle?
pleural pressure (Ppl
mouth pressure (Pao)
body surface pressure (Pbs)
alveolar pressure (Palv)
Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?
Pbs
Pao
Ppl
Palv
Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?
transthoracic pressure gradient (Ppl – Pbs)
transrespiratory pressure gradient (Palv – Pao)
transpulmonary pressure gradient (Palv – Ppl)
transcanadian pressure gradient (Ppc – Pks)
Which of the following pressure gradients is responsible for maintaining alveolar inflation?
transcanadian pressure gradient (Pca – Pks)
transthoracic pressure gradient (Ppl –Pbs)
Which of the following statements about alveolar pressure (Palv) during normal quiet breathing is true?
It always remains less than atmospheric pressure.
It is negative during inspiration and positive during expiration.
It is the same as intrapleural pressure (Ppl).
It is positive during inspiration and negative during expiration.
What happens during normal inspiration?
Palv drops below that at the airway opening.
The transpulmonary pressure gradient widens.
The Ppl decreases further below atmospheric.
During normal tidal ventilation, the transpulmonary pressure gradient (Palv – Ppl) reaches its maximum value at what point in the cycle?
mid-expiration
end-inspiration
end-expiration
mid-inspiration
During expiration, why does gas flow out from the lungs to the atmosphere?
Airway pressure is greater than Palv.
Palv is greater than at the airway opening.
Palv is the same as at the airway opening
Palv is less than at the airway opening.
What forces must be overcome to move air into the respiratory system?
surface tension forces
airway resistance
elastic forces of lung tissue
tissue movement
What term is used to note the difference between inspiratory lung volume and expiratory lung volume at any given pressure?
transpulmonary pressures
pleural pressure variance
hysteresis
alveolar aphasia
What is the effect of surface tension forces in the air-filled lung?
It decreases the lung's elasticity as volume increases
It makes the lung harder to inflate than if it were filled with fluid
It increases the elastic recoil of the lung (promoting collapse).
The presence of surfactant in the alveoli tends to do which of the following?
increase resistance
increase elastance
decrease surface tension
decrease compliance
How is compliance computed?
change in volume/change in pressure
change in volume/change in flow
change in pressure/change in volume
change in pressure/change in flow
Normal lung compliance is approximately which of the following?
10.00 L/cm H2O
2.00 L/cm H2O
0.20 L/cm H2O
0.01 L/cm H2O
A lung that loses elastic fibers (as in emphysema) would exhibit which of the following characteristics?
increased pulmonary compliance
increased airway resistance
decreased pulmonary vascular resistance
decreased airways resistance
A fibrotic lung would exhibit which of the following characteristics?
decreased surface tension
decreased PVR
decreased lung compliance
decreased airway resistance
What occurs at a lung volume equivalent to the functional residual capacity (FRC)?
Opposing chest-wall-lung forces generate negative Ppl.
Chest wall expansion is offset by lung contraction.
The forces of the chest wall and lungs are in balance.
At approximately what point during a maximum inspiration does the chest wall reach its natural resting level?
about 90% of the VC
about 70% of the VC
about 40% of the total lung capacity (TLC)
about 30% of the VC
