Question 1

Which of the following best describes the primary mechanism by which most carbon dioxide is transported in the blood from systemic tissues to the lungs?

Accepted Answer

Converted to bicarbonate ion ($$CO_2 + H_2O$$ \xrightarrow{CA} H_2CO_3 \rightarrow H^+ + $$HCO_3$$^-$$)

Question 2

A patient is exposed to carbon monoxide (CO). Which of the following best explains why CO poisoning leads to hypoxia despite normal arterial $$PO_2$$ levels?

Accepted Answer

CO binds to hemoglobin with much higher affinity than O2, preventing O2 binding

Question 3

During the chloride shift in systemic capillaries, which of the following occurs?

Accepted Answer

Chloride ions ($$Cl^-) $$move into the red blood cell as bicarbonate ($$HCO_3$$^-$$) exits

Question 4

Which equation correctly represents the reversible reaction catalyzed by carbonic anhydrase in red blood cells?

Accepted Answer

$$CO_2 + H_2O$$ \xrightarrow{CA} H_2CO_3 \rightarrow H^+ + $$HCO_3$$^-$$

Question 5

A climber at high altitude experiences a drop in arterial $$PO_2$$ below 60 mm Hg. Which chemoreceptors are primarily responsible for increasing ventilation in this scenario?

Accepted Answer

Peripheral chemoreceptors in the carotid and aortic bodies

Question 6

Which of the following best explains why hyperventilation before underwater swimming can be dangerous?

Accepted Answer

It decreases arterial $$PCO_2$$, delaying the urge to breathe and risking hypoxic blackout

Question 7

Which neural structure is considered the primary pacemaker for the respiratory rhythm in the medulla?

Accepted Answer

Pre-Bötzinger complex

Question 8

A patient with chronic obstructive pulmonary disease (COPD) develops chronic hypercapnia. Over time, which chemoreceptor becomes more important for regulating ventilation?

Accepted Answer

Peripheral chemoreceptors, due to decreased $$PO_2$$

Question 9

Which of the following best describes the effect of carbon monoxide (CO) on the hemoglobin-oxygen dissociation curve?

Accepted Answer

It causes a drastic leftward shift, reducing O2 release to tissues

Question 10

Which of the following is a direct result of the Hering-Breuer inflation reflex?

Accepted Answer

Inhibition of inspiration during extreme lung inflation

Question 11

A person is experiencing metabolic acidosis. Which of the following changes would you expect in their ventilation?

Accepted Answer

Increased ventilation due to increased $$[H^+]$$

Question 12

Which of the following best describes the role of the dorsal respiratory group (DRG) in the medulla?

Accepted Answer

Integrates sensory input and stimulates inspiratory muscles in a ramping pattern

Question 13

Which of the following best explains why alcohol consumption can increase the risk of aspiration?

Accepted Answer

Alcohol inhibits the cough reflex, reducing airway protection

Question 14

Which of the following is the correct sequence of events for CO2 transport from tissues to the lungs?

Accepted Answer

CO2 enters RBCs → converted to HCO3- → HCO3- exits RBCs via chloride shift

Question 15

Which of the following best describes the effect of a small increase in arterial $$PCO_2 on $$ventilation?

Accepted Answer

It increases ventilation by stimulating both central and peripheral chemoreceptors

Question 16

A patient with a closed pneumothorax is unable to inflate one lung. Which protective reflex is most likely to be affected?

Accepted Answer

Hering-Breuer inflation reflex

Question 17

Which of the following best explains why smokers may lose the ability to detect noxious chemicals in the airway?

Accepted Answer

Desensitization of irritant receptors in the airway

Question 18

Which of the following best describes the response of central chemoreceptors to increased $$PCO_2 in $$the cerebrospinal fluid?

Accepted Answer

They respond to increased $$[H^+]$$ generated from $$CO_2$$ hydration

Question 19

Which of the following best describes the effect of voluntary hyperventilation on arterial blood gases?

Accepted Answer

Decreased $$PCO_2$$ and increased $$PO_2$$

Unit 4- Ch 19 Pt 2 Gas Exchange, Transport, and Control of Ventilation

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