Question 1

Which of the following best describes the primary way oxygen is transported in the blood?

Accepted Answer

Bound to the iron in the heme group of hemoglobin

Question 2

The oxygen-hemoglobin dissociation curve is sigmoidal because:

Accepted Answer

The binding of one O2 molecule increases the affinity for the next O2 molecule

Question 3

Which of the following factors will shift the oxygen-hemoglobin dissociation curve to the right, thereby promoting oxygen unloading at the tissues?

Accepted Answer

Increased 2,3-BPG concentration

Question 4

What is the Bohr effect?

Accepted Answer

The decreased affinity of hemoglobin for oxygen due to increased H+ and CO2

Question 5

During vigorous exercise, why does hemoglobin still remain about 75% saturated with oxygen in venous blood?

Accepted Answer

Because only about 25% of oxygen is normally unloaded during one systemic circuit (venous reserve)

Question 6

Which equation correctly represents the reversible reaction for carbon dioxide transport as bicarbonate in the blood?

Accepted Answer

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

Question 7

Which of the following best explains the Haldane effect?

Accepted Answer

Deoxygenated hemoglobin binds more CO2 than oxygenated hemoglobin

Question 8

How does slow, shallow breathing affect blood pH?

Accepted Answer

It decreases blood pH by causing CO2 accumulation

Question 9

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

Accepted Answer

Ventral respiratory group (VRG)

Question 10

A patient overdoses on morphine, which suppresses the VRG. What is the most likely consequence?

Accepted Answer

Complete cessation of breathing (apnea)

Question 11

Which of the following is the most potent and closely regulated chemical factor influencing respiration under normal conditions?

Accepted Answer

Arterial PCO2

Question 12

Why does a large drop in arterial PO2 (to below 60 mm Hg) become an important stimulus for increased ventilation?

Accepted Answer

Because oxygen sensors in the aortic and carotid bodies are strongly activated

Question 13

Which of the following best describes the chloride shift in red blood cells?

Accepted Answer

Chloride ions move into RBCs as bicarbonate leaves

Question 14

During intense exercise, what is the primary reason that arterial PO2 and PCO2 remain relatively constant despite increased O2 consumption and CO2 production?

Accepted Answer

Increased ventilation matches the increased metabolic demand

Question 15

Which of the following is a protective reflex that prevents over-inflation of the lungs?

Accepted Answer

Hering-Breuer reflex

Question 16

Which of the following best explains why hyperventilation before a dive can increase the risk of shallow water blackout?

Accepted Answer

It lowers arterial PCO2, delaying the urge to breathe and risking hypoxia before CO2 levels trigger respiration

Question 17

Which of the following is true regarding the control of breathing during rest?

Accepted Answer

It is primarily aimed at regulating [H+] in the brain

Question 18

Which of the following is NOT a way that the nervous system can influence respiration?

Accepted Answer

The cerebellum directly stimulates the VRG to increase breathing rate

Question 19

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

Accepted Answer

Most CO2 is transported as bicarbonate ions in plasma

Question 20

A person is experiencing metabolic acidosis due to excess lactic acid. How will the respiratory system respond?

Accepted Answer

Increase rate and depth of breathing to expel CO2 and raise blood pH

The Respiratory System: Gas Transport and Regulation

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