Question 1

What brain center has neurons that fire mainly during inspiration and have input to the spinal motor neurons that activate the diaphragm and inspiratory intercostal muscles?

Accepted Answer

The dorsal respiratory group (DRG) of the medulla oblongata contains neurons that are primarily active during inspiration and project to the spinal motor neurons that control the diaphragm and inspiratory intercostal muscles.

Question 2

You walk into your dorm room and find your roommate in the midst of anxiety-induced hyperventilation.You're unable to calm her down,so you call an ambulance.When she arrives at the ER,which of the following is her likely diagnosis?

Accepted Answer

Hyperventilation leads to excessive exhalation of CO₂, which decreases blood CO₂ levels and increases blood pH, resulting in respiratory alkalosis.

Question 3

You're resting on the couch watching TV.Which of the following is the most likely reflection of the values in your body? Regarding the partial pressures of O₂ and CO₂,which of the following statements is true in a normal person at rest?

Accepted Answer

Option C is the only statement that accurately reflects the typical partial pressures of O₂ and CO₂ in a normal person at rest. Atmospheric PO₂ is indeed ~100 mmHg, but alveolar PO₂ is around 100 mmHg as well, not 160 mmHg (option A is incorrect). The PCO₂ in the air is indeed ~40 mmHg, but the alveolar PCO₂ is around 40 mmHg as well, not 60 mmHg (option B is incorrect). Option D and E are both incorrect, as systemic venous PCO₂ is greater than systemic arterial PCO₂ (due to CO₂ produced by the body's cells) and pulmonary arterial PCO₂ is greater than pulmonary venous PCO₂ (since the lungs remove CO₂ from the blood).

Question 4

During a run,your gastrocnemius (calf)muscle has a temperature of 38.5° C,while your biceps brachii (upper arm)muscle has a temperature of 37.5° C.Which of the following is TRUE of the red blood cells as they pass by these muscles?

Accepted Answer

Hemoglobin's affinity for oxygen decreases with an increase in temperature. Therefore, as it passes by the cooler biceps brachii muscle (37.5° C), its affinity for oxygen will be higher compared to when it passes by the warmer gastrocnemius muscle (38.5° C).

Question 5

Which of these is demonstrated by the oxygen-hemoglobin dissociation curve?

Accepted Answer

The answer of Which of these is demonstrated by the...

Question 6

You embark on a hiking trip on Mt.Kilimanjaro (altitude = 19,000 ft;Atmospheric air pressure = 379 mmHg).As you ascend,what happens to the PO₂ in the alveoli?

Accepted Answer

As altitude increases, atmospheric pressure decreases. This causes air to become less dense, which means there are fewer oxygen molecules per volume of air. As a result, the alveolar PO₂ decreases. This can lead to altitude sickness and other complications related to oxygen deprivation. It is important to acclimate gradually to higher altitudes and maintain proper oxygenation.

Question 7

Regarding the relationships between the rates of oxygen consumption/carbon dioxide production and alveolar ventilation,which of these statements is TRUE?

Accepted Answer

A decrease in metabolism without a similar decrease in alveolar ventilation would result in hyperventilation because the body would be expelling CO2 at a rate higher than it is produced, leading to decreased alveolar and blood CO2 levels.

Question 8

Action potentials in neurons in the inspiratory center of the medulla oblongata result in action potentials in the ________ nerves to the diaphragm,which in turn cause ________ of the muscle,resulting in a/an ________ in the volume of the thoracic cage.

Accepted Answer

Action potentials in neurons in the inspiratory center of the medulla oblongata lead to action potentials in motor nerves to the diaphragm, causing contraction of the muscle. This contraction results in an increase in the volume of the thoracic cage, facilitating inhalation.

Question 9

When you head to bed at night,you bring a glass of tap water with you and set it on the nightstand.Upon waking in the morning,you discover there are tiny gas bubbles along the sides of the container.The best explanation for this is

Accepted Answer

The tiny gas bubbles on the sides of the container suggest that gas has diffused from the air into the water. Based on this, the best explanation is that the partial pressure of the gas in the water has equilibrated with the partial pressure of the gas in the air surrounding the container. Therefore, the correct answer is D, "the partial pressure of a particular gas in a liquid equilibrates to match the partial pressure of that gas in the air to which the liquid is exposed."

Question 10

Which of the following would cause a decrease in the binding affinity of hemoglobin for oxygen?

Accepted Answer

An increase in temperature causes a decrease in the binding affinity of hemoglobin for oxygen, resulting in a rightward shift of the oxygen-hemoglobin dissociation curve.

Question 11

A decrease in metabolism without a similar,compensatory decrease in alveolar ventilation will have what effect on the systemic pH?

Accepted Answer

A decrease in metabolism typically means less production of carbon dioxide (CO2), a byproduct of metabolic processes. If alveolar ventilation remains unchanged, the body will eliminate more CO2 than it produces, leading to a decrease in the partial pressure of CO2 in blood. This decrease in CO2, which acts as an acid in the body, will cause a reduction in hydrogen ion concentration, thereby increasing the pH and making the blood more alkaline.

Question 12

You embark on a hiking trip on Mt.Kilimanjaro (altitude = 19,000 ft;Atmospheric air pressure = 379 mmHg).mHg).As you ascend,what are you likely to notice about your breathing?

Accepted Answer

As you ascend to higher altitudes, the atmospheric pressure decreases. This makes it harder for air to enter your lungs during inhalation because there is less pressure pushing the air in. Therefore, you would need to work harder to expand your thoracic size beyond what is normal to inhale the same amount of air. Exhalation, on the other hand, should not be affected as much as inhalation.

Question 13

In which form is most of the oxygen carried in arterial blood?

Accepted Answer

Most of the oxygen is carried in arterial blood bound to hemoglobin, a protein found in red blood cells. Only a small fraction is dissolved in the plasma.

Question 14

You (a healthy individual)are swimming underwater when you can no longer resist the urge to breathe.This overwhelming urge is probably due to

Accepted Answer

The overwhelming urge to breathe when swimming underwater is primarily due to the increase in plasma H⁺, which is a result of CO₂ accumulation in the blood. This leads to a decrease in blood pH (acidosis), stimulating chemoreceptors to trigger the urge to breathe.

Question 15

Maria is a patient in the ward who was recently in a motor vehicle accident.Her injuries are causing her a lot of pain,and as a consequence to the morphine she's been given,her respiratory rate is quite low.Which of the following is likely to be TRUE?

Accepted Answer

Morphine is a respiratory depressant, which means it slows down the respiratory rate. This can cause a buildup of CO₂ in the blood, leading to an increase in the level of H⁺ ions and a decrease in blood pH. The level of O₂ in the blood may decrease due to poor oxygenation, and alveolar CO₂ levels may increase due to hypoventilation. The alveolar O₂ levels may decrease due to poor oxygenation. Therefore, the correct answer is C.

Question 16

Which of these correctly describes the chloride shift?

Accepted Answer

The chloride shift refers to the movement of chloride ions (Cl⁻) into red blood cells (RBCs) in exchange for bicarbonate ions (HCO₃⁻) which occurs in the tissues. This is important because as RBCs release oxygen to the tissues, carbon dioxide (CO₂) is produced and converted to HCO₃⁻. Without the chloride shift, HCO₃⁻ would build up in RBCs and inhibit the conversion of CO₂, leading to acidification of tissues. The exchange of Cl⁻ for HCO₃⁻ helps maintain proper pH balance in the body. Option A is incorrect because in the lungs, the opposite exchange occurs - Cl⁻ leaves RBCs in exchange for HCO₃⁻. Option B is incorrect because carbonic acid is not exchanged for Cl⁻ during the chloride shift. Options D and E are also incorrect because CO₂ is not directly involved in the chloride shift.

Question 17

If all other factors remain the same,which of these results in an increase in the amount of oxygen bound to hemoglobin?

Accepted Answer

An increase in plasma PO₂ leads to an increase in the amount of oxygen bound to hemoglobin. This is due to the fact that the binding of oxygen to hemoglobin is an oxygen-dependent process. As the oxygen levels in the plasma increase, more oxygen molecules bind to the hemoglobin, leading to an increase in the amount of oxygen bound to the hemoglobin.

Question 18

After CO₂ is produced by tissues,in what form is most of that carbon transported to the lungs for removal from the body?

Accepted Answer

The majority of CO₂ from tissues is transported to the lungs in the form of dissolved bicarbonate ions (HCO₃⁻) in the plasma, which is formed by the reaction of CO₂ with water to form carbonic acid (H₂CO₃), which then dissociates into HCO₃⁻ and H+. This reaction is catalyzed by the enzyme carbonic anhydrase, but carbonic anhydrase itself is not transported to the lungs. CO₂ can also be transported in a smaller amount by being bound to hemoglobin or dissolved directly in the plasma, but these do not make up the majority of CO₂ transport.

Question 19

Carbonic anhydrase catalyzes a reaction that combines which of the following?

Accepted Answer

Carbonic anhydrase catalyzes the reversible reaction between carbon dioxide (CO2) and water (H2O) to form carbonic acid (H2CO3), which dissociates to bicarbonate (HCO3-) and a hydrogen ion (H+).

Question 20

Which of the following is NOT true regarding ventilation-perfusion inequality?

Accepted Answer

Ventilation-perfusion (V/Q) inequality is a normal physiological state that exists in all lungs. It refers to the mismatch between ventilation and blood flow in the lungs.

Quiz 13: Respiratory Physiology

What brain center has neurons that fire mainly during inspiration and have input to the spinal motor neurons that activate the diaphragm and inspiratory intercostal muscles?

You walk into your dorm room and find your roommate in the midst of anxiety-induced hyperventilation.You're unable to calm her down,so you call an ambulance.When she arrives at the ER,which of the following is her likely diagnosis?

You're resting on the couch watching TV.Which of the following is the most likely reflection of the values in your body? Regarding the partial pressures of O₂ and CO₂,which of the following statements is true in a normal person at rest?

During a run,your gastrocnemius (calf) muscle has a temperature of 38.5° C,while your biceps brachii (upper arm) muscle has a temperature of 37.5° C.Which of the following is TRUE of the red blood cells as they pass by these muscles?

Which of these is demonstrated by the oxygen-hemoglobin dissociation curve?

You embark on a hiking trip on Mt.Kilimanjaro (altitude = 19,000 ft;Atmospheric air pressure = 379 mmHg) .As you ascend,what happens to the PO₂ in the alveoli?

Regarding the relationships between the rates of oxygen consumption/carbon dioxide production and alveolar ventilation,which of these statements is TRUE?

Action potentials in neurons in the inspiratory center of the medulla oblongata result in action potentials in the nerves to the diaphragm,which in turn cause of the muscle,resulting in a/an in the volume of the thoracic cage.

When you head to bed at night,you bring a glass of tap water with you and set it on the nightstand.Upon waking in the morning,you discover there are tiny gas bubbles along the sides of the container.The best explanation for this is

Which of the following would cause a decrease in the binding affinity of hemoglobin for oxygen?

A decrease in metabolism without a similar,compensatory decrease in alveolar ventilation will have what effect on the systemic pH?

You embark on a hiking trip on Mt.Kilimanjaro (altitude = 19,000 ft;Atmospheric air pressure = 379 mmHg) .mHg) .As you ascend,what are you likely to notice about your breathing?