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MEDSCI 142 - Respiratory Physiology Exam
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MEDSCI 142 - Respiratory Physiology Exam...
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MEDSCI 142 - Respiratory Physiology ExamTidal volume is always:
a) greater than zero and less that total lung capacity
b) greater than residual volume
c) greater than functional residual capacity
d) greater than residual capacity and less than total lung capacity
e) all options are correct - ANSWER a - correct; tidal volume is the amount you breathe
in and out when relaxed so is less than maximum but more than zero
b - no; cant measure residual volume so dont know
c - no; FRC includes residual capacity which cant be measured
d - no; less than total lung capacity but dont know volume of residual capacity
e - no
The lung:
a) exchanges CO2 between alveolar air and pulmonary capillary blood
b) exchanges H2O between alveolar air and ambient air
c) exchanges heat between alveolar air and ambient air
d) exchanges O2 between alveolar air and pulmonary capillary blood
e) all of the above - ANSWER e - all of the above; the lung serves all of these functions
Excitation of the phrenic nerve will:
a) increase volume of thorax by causing elevation of diaphragm
b) reduce volume of thorax by causing elevation of the diaphragm
c) increase volume of the thorax by causing relaxation of the diaphragm
d) increase volume of the thorax by causing contraction of the diaphragm
,e) reduce volume of the thorax by causing contraction of the diaphragm - ANSWER a -
no; elevation of diaphragm will decrease volume
b - no; excitation of the nerve will not cause elevation of diaphragm
c - no; excitation will not relax the diaphragm
d - correct; excitation will contract the diaphragm, which for a dome-shaped muscle
means going down and increasing volume of the thorax
e - no; contraction causes expansion of volume
During inspiration:
a) the glottis is open and alveolar air pressure is above atmospheric
b) the glottis is open and alveolar air pressure is equal to atm
c) the glottis is open and alveolar air pressure is less that atm
d) the glottis is closed and alveolar air pressure is above atm
e) the glottis is closed and alveolar air pressure is below atm - ANSWER If alveolar air
pressure was above atmospheric, it would want to equilibrate and the air would leave
the lungs, not go in. Because of expansion of the alveoli, the pressure drops. The glottis
is only closed for swallowing food, so
c - correct
Pneumonia In pneumonia, a bacterial infection causes the alveoli to fill with fluid,
thereby reducing the space for air. This condition would be expected to: a) decrease the
surface area for diffusive exchange of O2 b) decrease the surface are for diffusive
exchange of CO2 c) increase the diffusion distance of O2 between air and blood d)
increase the diffusion distance of CO2 between air and blood
e) all of the above - ANSWER Decreased space for air means there is less surface area
available for gas exchange, but it also means more thickness that the exchange needs
to have to work through
e- all of the above
Ventilation is increased by:
a) a decrease in partial pressure of CO2 in the cerebrospinal fluid
, b) a decrease in partial pressure of CO2 in the blood supply to the carotid bodies
c) decrease in partial pressure of CO2 in the inspired air
d) decrease of pH of the cerebrospinal fluid
e) all options are correct - ANSWER Increase in ventilation is usually due to lower O2,
and a need to increase O2. A decrease in CO2 would not trigger this.
d - decrease in pH can occur due to increase in CO2 so ventilation is needed to correct
pH
Hyperventilation will lead to :
a) increase of arteriolar Po2
b) decrease of alveolar Po2
c) increase of alveolar Pco2
d) increase of arteriolar Pco2
e) all options are correct - ANSWER a - correct, more oxygen will go into the blood
b - no, Po2 at alveoli will not change, just the total amount
c - no, same as above
d - no, breathing in more will not lead to more Pco2 in arteries
e - no
The human pulmonary system:
a) senses Po2 and Pco2 in the carotid and aortic bodies
b) is responsive to the pH of the cerebrospinal fluid
c) is more responsive to an excess of CO2 than to lack of O2
d) contain stretch receptors in lung tissue
e) all options are correct
ANSWER a - yes, peripheral chemoreceptors are located here
b - yes, H ions will trigger the central chemoreceptors
c-yes, dog-leg relationship graph c.f. Po2 graph
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