Question 1

Which of the following best describes the effect of low alveolar oxygen ($$O_2) on $$the diameter of pulmonary arterioles?

Accepted Answer

Pulmonary arterioles constrict to decrease blood flow to the alveoli.

Question 2

In the lungs, what is the physiological purpose of bronchiolar dilation in response to high alveolar carbon dioxide ($$CO_2$$)?

Accepted Answer

To allow rapid elimination of carbon dioxide from the alveoli.

Question 3

Which of the following statements correctly compares the response of systemic arterioles to oxygen levels with that of pulmonary arterioles?

Accepted Answer

Systemic arterioles dilate when oxygen is low, while pulmonary arterioles constrict.

Question 4

During external respiration, which direction does oxygen ($$O_2) $$diffuse, and what is the primary driving force?

Accepted Answer

From alveoli into pulmonary capillaries, driven by higher $$O_2 in $$alveoli.

Question 5

Which of the following factors will cause the oxygen-hemoglobin dissociation curve to shift to the right?

Accepted Answer

Increased concentration of BPG ($$2,3-$$bisphosphoglycerate)

Question 6

A patient is exercising vigorously, leading to increased $$CO_2$$ production and decreased blood pH. What effect does this have on hemoglobin's affinity for oxygen, and what is this phenomenon called?

Accepted Answer

Affinity decreases; Bohr effect

Question 7

Which of the following equations represents the carbonic acid-bicarbonate buffer system in the blood?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3 \rightarrow $$HCO_3^- + H$$^+$$

Question 8

In the systemic capillaries, what is the direction of the chloride shift, and why does it occur?

Accepted Answer

Chloride ions move into red blood cells to balance bicarbonate efflux.

Question 9

Which region of the brain is primarily responsible for setting the basic rhythm of breathing?

Accepted Answer

Medulla oblongata

Question 10

Which chemical factor is most closely controlled to regulate breathing rate and depth, and why?

Accepted Answer

Partial pressure of carbon dioxide ($$P_{CO_2$}$$), because small changes have a large effect on pH.

Question 11

A patient with chronic obstructive pulmonary disease (COPD) has elevated $$CO_2$$ levels. Which of the following best explains the effect on blood pH?

Accepted Answer

Blood pH decreases due to increased carbonic acid formation.

Question 12

Which of the following best describes the Haldane effect?

Accepted Answer

Deoxygenated hemoglobin binds $$CO_2$$ more readily, facilitating $$CO_2$$ transport.

Question 13

Which of the following scenarios would most likely trigger the Hering-Breuer reflex?

Accepted Answer

Excessive stretching of the lungs during deep inspiration

Question 14

A person is exposed to high altitude, resulting in decreased $$P_{O_2$} in $$the alveoli. What is the expected response of pulmonary arterioles and why?

Accepted Answer

Pulmonary arterioles constrict to divert blood to better-ventilated alveoli.

Question 15

Which of the following best explains why the partial pressure gradients for $$O_2$$ and $$CO_2$$ are reversed between external and internal respiration?

Accepted Answer

Because $$O_2$$ diffuses from alveoli to blood during external respiration, and from blood to tissues during internal respiration.

Question 16

Which of the following is NOT a factor that shifts the oxygen-hemoglobin dissociation curve to the right?

Accepted Answer

Decreased $$CO_2$$ partial pressure

Question 17

During hyperventilation, which of the following changes occurs in the blood?

Accepted Answer

Decreased $$CO_2$$ and increased pH

Question 18

Which of the following best describes the role of the pons in respiratory control?

Accepted Answer

Modifies and smooths the respiratory rhythm.

Question 19

A patient has a blood pH of 7.25, $$P_{CO_2$} of 55 $$mmHg, and $$P_{O_2$} of 90 $$mmHg. Which of the following is the most likely cause of the increased breathing rate?

Accepted Answer

High $$P_{CO_2$}$$ stimulating central chemoreceptors and lowering pH.

Respiratory Physiology: Gas Exchange, Transport, and Regulation

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