Q: At high altitude, the atmospheric pressure is 250 mmHg. Using the formula $$PO_2$$ = \text{total pressure} \times \text{fraction of O}_2$$, what is the PO_2$ at the peak of Everest if the fraction of O_2$ is 0.2093?

$$PO_2 = 250$$ \times 0.2093 = 52.3$$ mmHg

Question 1

Which of the following best explains why oxygen diffuses from the alveoli into the pulmonary capillaries?

Accepted Answer

The partial pressure of oxygen ($$PO_2) is $$higher in the alveoli than in the pulmonary capillaries.

Question 2

A patient is experiencing hypoventilation. Which of the following changes in arterial blood gases would you expect?

Accepted Answer

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

Question 3

At high altitude, the atmospheric pressure is 250 mmHg. Using the formula $$PO_2$$ = 	ext{total pressure} 	imes 	ext{fraction of O}_2$$, what is the PO_2$ at the peak of Everest if the fraction of O_2$ is 0.2093?

Accepted Answer

$$PO_2 = 250$$ 	imes 0.2093 = 52.3$$ mmHg

Question 4

Which of the following best describes the Bohr effect?

Accepted Answer

A decrease in pH decreases the affinity of hemoglobin for oxygen, shifting the oxyhemoglobin dissociation curve to the right.

Question 5

Which of the following is the primary way carbon dioxide is transported in the blood?

Accepted Answer

As bicarbonate ions ($$HCO_3$$^-$$) in plasma

Question 6

A rightward shift in the oxyhemoglobin dissociation curve will result in which of the following?

Accepted Answer

Decreased affinity of hemoglobin for oxygen and increased oxygen unloading at the tissues

Question 7

Which of the following conditions would most likely cause a leftward shift in the oxyhemoglobin dissociation curve?

Accepted Answer

Decreased temperature

Question 8

What is the effect of 2,3-diphosphoglycerate (2,3-DPG) on hemoglobin's affinity for oxygen?

Accepted Answer

It decreases hemoglobin's affinity for oxygen, enhancing oxygen unloading at the tissues.

Question 9

Which of the following best describes the law of mass action as it applies to the reaction catalyzed by carbonic anhydrase?

Accepted Answer

An increase in $$CO_2$$ will drive the reaction $$CO_2 + H_2O$$ \xrightleftharpoons[	ext{carbonic anhydrase}]{} H_2CO_3$$ to produce more H_2CO_3$.

Question 10

A patient with anemia is likely to have increased levels of 2,3-DPG in their red blood cells. What is the physiological significance of this adaptation?

Accepted Answer

It promotes oxygen unloading from hemoglobin to compensate for reduced oxygen-carrying capacity.

Question 11

Which of the following statements about oxygen transport in blood is correct?

Accepted Answer

Most oxygen is transported bound to hemoglobin, with only a small fraction dissolved in plasma.

Question 12

During exercise, active tissues produce more $$CO_2$$ and $$H^+. $$What is the effect on the oxyhemoglobin dissociation curve and oxygen delivery?

Accepted Answer

The curve shifts to the right, increasing oxygen unloading to the tissues.

Question 13

Which of the following best describes the effect of carbon monoxide (CO) on oxygen transport?

Accepted Answer

CO binds to hemoglobin with greater affinity than oxygen, preventing oxygen from binding.

Question 14

If a person is hyperventilating, what changes would you expect in their arterial blood gases?

Accepted Answer

Increased $$PO_2$$ and decreased $$PCO_2$$

Question 15

Which of the following is a direct consequence of impaired diffusion across the respiratory membrane?

Accepted Answer

Hypoxia and hypercapnia

Question 16

Which of the following best explains why the $$PO_2 in $$systemic veins is lower than in systemic arteries?

Accepted Answer

Oxygen diffuses from the blood into the tissues, lowering $$PO_2 in $$the veins.

Question 17

Which of the following terms describes a deficiency of oxygen in the tissues?

Accepted Answer

Hypoxia

Question 18

A patient is exposed to high levels of carbon dioxide. According to the law of mass action, what will happen to the concentration of bicarbonate ($$HCO_3$$^-$$) in their blood?

Accepted Answer

It will increase as more $$CO_2 is $$converted to $$HCO_3$$^-$$.

Question 19

Which of the following is NOT a factor that would decrease the affinity of hemoglobin for oxygen?

Accepted Answer

Decreased temperature

Gas Exchange and Transport in Human Physiology

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