Deck 17: The Respiratory System: Gas Exchange and the Regulation of Breathing

Question 1

Which of the following can increase the concentration of a particular gas in a solution?

A) Increase the volume of the solution only.
B) Increase the volume of the container containing the gas and solution.
C) Increase the volume of the gas only.
D) Decrease the concentration of other gases in the solution.
E) Increase the partial pressure of that gas exposed to the solution.

Answer 1

E

Question 2

What percentage of air is carbon dioxide?

A) 6%
B) 79%
C) 12%
D) < 1%
E) 21%

Answer 2

D

Question 3

Which statement best describes the cause of decompression sickness?

A) Oxygen molecules are so tightly compressed due to pressure exerted by the water column that they cannot deliver oxygen to the tissues.
B) The oxygen molecule expands upon ascent and bursts, therefore causing a lack of oxygen to the tissues.
C) Carbon dioxide is driven into the cardiovascular system and causes acidosis.
D) Carbon dioxide bubbles come out of solution too quickly and burst blood vessels, especially in the brain.
E) Nitrogen gas bubbles form in the blood, joints, and nervous system as pressure decreases from too fast an ascent.

Answer 3

E

Question 4

Which of the following does NOT contribute to the rapid movement of gases into and out of the blood within the lungs?

A) thin membrane
B) permeability of the membrane
C) rapid blood flow
D) concentration gradient
E) large surface area

Question 5

What is the partial pressure of oxygen in air at sea level?

A) 400 mm Hg
B) 160 mm Hg
C) 60 mm Hg
D) 600 mm Hg
E) 210 mm Hg

Question 6

At equilibrium, which of the following statements is TRUE when helium and nitrogen are present in a gas at equal partial pressures over water?

A) The concentrations of helium and nitrogen in both the water and gas are equal.
B) The concentrations of helium and nitrogen in the water are equal.
C) The concentrations of helium and nitrogen in the gas are equal.
D) The partial pressures of helium and nitrogen in the water are equal.
E) The partial pressure of nitrogen is greater than the partial pressure of helium.

Question 7

What percentage of air is oxygen?

A) 21%
B) 12%
C) 6%
D) < 1%
E) 79%

Question 8

Movement of oxygen and carbon dioxide between alveoli and blood occurs by what process?

A) facilitated diffusion
B) osmosis
C) simple diffusion
D) primary active transport
E) secondary active transport

Question 9

At sea level, if oxygen is consumed by the body cells at a rate of 300 mL per minute, then how much oxygen diffuses from the alveoli into the blood in the pulmonary capillaries?

A) 300 mL per minute
B) more than 300 mL per minute
C) less than 300 mL per minute
D) It depends on where the oxygen is being utilized.
E) It depends on whether or not carbon dioxide is being produced at the same rate.

Question 10

What is the most abundant gas in the air that we breathe?

A) water vapor
B) oxygen
C) hydrogen
D) carbon dioxide
E) nitrogen

Question 11

Which statement best describes why O₂ and CO₂ can both be exchanged simultaneously at the alveoli and pulmonary capillaries?

A) Blood in both the alveoli and pulmonary capillaries is at equilibrium.
B) Blood in the alveoli is high in both O₂ and CO_2.
C) Each gas acts independently and diffuses down its own partial pressure gradient.
D) Nitrogen is at a high pressure in both the alveoli and pulmonary capillaries and drives the exchange of O₂ and CO₂.
E) Blood in the pulmonary capillaries is high in both O₂ and CO_2.

Question 12

At equilibrium, the gas molecules that dissolve in solution and those that remain in the gaseous phase are, by definition, at the same

A) partial pressure.
B) humidity.
C) concentration.
D) temperature.
E) volume.

Question 13

What is the partial pressure of oxygen in a gas mixture that is 40% oxygen, 40% argon, and 20% helium, when the total pressure of the gas is 1000 mm Hg?

A) 100 mm Hg
B) 400 mm Hg
C) 600 mm Hg
D) 333 mm Hg
E) 200 mm Hg

Question 14

Oxygenated blood is found in which of the following?

A) right atrium only
B) pulmonary artery only
C) pulmonary vein only
D) both the right atrium and pulmonary artery
E) both the right atrium and pulmonary vein

Question 15

As humidity increases, the partial pressure of oxygen in air

A) increases as the total pressure of air remains the same.
B) increases as the total pressure of air increases.
C) decreases as the total pressure of air remains the same.
D) decreases as the total pressure of air increases.
E) does not change.

Question 16

The relationship between the concentration of a gas in solution and the partial pressure of that gas can be described by

A) Dalton's law.
B) Henry's law.
C) Fick's law.
D) Boyle's law.
E) Poiseuille's law.

Question 17

In a mixture of gases, the driving force for the movement of an individual gas within that mixture is ultimately the

A) partial pressure of that gas.
B) volume of the gas.
C) solubility of the gas.
D) fractional concentration of that gas.
E) total pressure of the gases.

Question 18

At sea level the air pressure which equals 1 atmosphere is

A) 100 mm Hg.
B) 500 mm Hg.
C) 150 mm Hg.
D) 760 mm Hg.
E) 600 mm Hg.

Question 19

The respiratory quotient is calculated as the

A) ratio of the volume of carbon dioxide produced per volume of oxygen consumed.
B) ratio of the volume of oxygen consumed per volume of carbon dioxide produced.
C) sum of the volume of oxygen consumed and the volume of carbon dioxide produced.
D) product of the volume of carbon dioxide consumed and the volume of oxygen produced.
E) product of the volume of oxygen consumed and the volume of carbon dioxide produced.

Question 20

As the air is saturated with water vapor (humidified) upon entry into the conducting pathway, there will be

A) a selective decrease in the partial pressure of nitrogen.
B) a selective increase in the partial pressure of nitrogen.
C) no change in the partial pressure of the remaining gases.
D) an increase in the partial pressure of the remaining gases.
E) a decrease in the partial pressure of the remaining gases.

Question 21

What percentage of oxygen is transported by hemoglobin?

A) 86%
B) 98.5%
C) 5%
D) 1.5%
E) 75%

Question 22

Each on the hemoglobin subunit is capable of binding an oxygen molecule, thereby allowing

A) globin : three oxygen to bind with one hemoglobin molecule.
B) free iron : one
C) heme : four
D) heme : three
E) globin : four

Question 23

What is the primary driving force for the binding of oxygen to hemoglobin?

A) pH
B) P_O2
C) temperature
D) 2,3 -bisphosphoglycerate (2,3 -BPG)
E) P_CO2

Question 24

Pulmonary edema describes a condition where the uptake of oxygen and unloading of carbon dioxide is reduced as a consequence of a(n)

A) decrease in the partial pressure of oxygen in the alveolus.
B) thickening of the diffusion barrier by fluid accumulation in the alveoli.
C) increase in the partial pressure of oxygen in the blood.
D) thickening of the diffusion barrier by fluid accumulation in the pulmonary blood.
E) decrease in the partial pressure of carbon dioxide in the alveolus.

Question 25

What is an increase in alveolar ventilation to match the demands of increased metabolic activity in the cells called?

A) hyperpnea
B) dyspnea
C) hypoventilation
D) hypopnea
E) hyperventilation

Question 26

What is the most common cause of pulmonary edema?

A) left heart failure
B) collapsed lung
C) right heart failure
D) blood clot
E) kidney failure

Question 27

Mixed venous blood samples can be taken from which of the following blood vessels?

A) superior vena cava
B) pulmonary artery
C) aorta
D) inferior vena cava
E) pulmonary vein

Question 28

What percentage of oxygen is transported in the plasma?

A) 75%
B) 98.5%
C) 5%
D) 1.5%
E) 86%

Question 29

The mixing of atmospheric air within the dead space of the conducting zone of the lung upon inspiration results in a partial pressure of

A) nitrogen in the alveoli that is higher than atmospheric.
B) water vapor in the alveoli that is lower than atmospheric.
C) oxygen in the alveoli that is lower than atmospheric.
D) carbon dioxide in the alveoli that is lower than atmospheric.
E) oxygen in the alveoli that is higher than atmospheric.

Question 30

The majority of oxygen present within the blood is

A) dissolved within the plasma.
B) bound to plasma proteins.
C) bound to hemoglobin in red blood cells.
D) bound to hemoglobin within the plasma.
E) in the plasma as HCO₃ ^-.

Question 31

Which statement best describes why the law of mass action explains the loading and unloading of oxygen in hemoglobin?

A) Oxygen has a greater mass than carbon dioxide and therefore can load more quickly than carbon dioxide.
B) The mass of both carbon dioxide and oxygen is the same and therefore they exchange at the same rates
C) As oxygen level rises, so does the pressure, which breaks the bonds of hemoglobin thereby releasing hemoglobin to the tissues.
D) As oxygen levels in the pulmonary capillaries increase, more oxyhemoglobin is formed. Conversely, as oxygen levels in the systemic capillaries decrease, the reaction reverses and releases oxygen from hemoglobin.
E) As oxygen levels in the pulmonary capillaries decrease, more carbaminohemoglobin is formed due to the concentration of carbon dioxide.

Question 32

Gangrene is often caused by anaerobic bacteria deep in tissues that lack adequate blood flow and adequate oxygen supply. Many times, gangrene can be treated by putting the patient into a hyperbaric chamber. Which statement best describes why this type of therapy is effective?

A) The increased pressure destroys the cell wall of the bacteria.
B) When the patient is brought back to normal atmospheric pressure, carbon dioxide comes out of solution at high concentrations, which poisons the bacteria.
C) The increased pressure drives nitrogen into the system and nitrogen gas poisons the bacteria.
D) The increased pressure drives more oxygen into the bloodstream and, therefore, anaerobic bacteria cannot survive in the presence of oxygen.
E) The increased pressure creates a higher pressure in the capillaries of the tissue and drives the toxin produced by the bacteria into the bloodstream, where it is diluted.

Question 33

Which of the following causes a decrease in the P_O2 of air as it enters the conducting zone of the lungs?

A) the increasing P_CO2
B) the consumption of oxygen
C) decreasing alveolar P_O2
D) humidifying the air
E) warming of the air

Question 34

What is a decrease in carbon dioxide within the blood called?

A) hypoxia
B) hypercapnia
C) hypocapnia
D) hypoxemia
E) hyperpnea

Question 35

The venous blood in the right ventricle is referred to as "mixed" because the blood that enters the heart

A) comes from tissue with differing metabolic activities.
B) has a high P_CO2.
C) is drained from the body.
D) contains a mixture of oxygen and carbon dioxide.
E) has a low P_O2.

Question 36

Hyperventilation would lead to a(n) _

A) selective decrease in P_O2
B) increase in P_O2 and decrease in P_CO2
C) selective increase in P_O2
D) selective decrease in P_CO2
E) decrease in P_O2 and increase in P_CO2

Question 37

Your patient is in the hospital due to left heart failure. In your observation, you notice that she has a very low pulse oximeter reading, her skin is turning blue, and she appears to be in respiratory distress (rapid shallow breathing). You immediately call the doctor because you recognize that these symptoms indicate

A) prolapsed heart valve
B) decompression sickness
C) internal bleeding
D) pulmonary edema
E) myocardial infarction

Question 38

Hypoventilation would lead to a(n)

A) selective increase in P_O2
B) selective decrease in P_CO2
C) increase in P_O2 and decrease in P_CO2
D) selective decrease in P_O2
E) decrease in P_O2 and increase in P_CO2

Question 39

During intense exercise, the metabolic activity of muscle causes in the partial pressure of
Oxygen in the tissue,

A) a decrease : facilitating
B) an increase : reducing _ the movement of oxygen into the tissue.
C) an increase : facilitating
D) a decrease : reducing
E) no change : facilitating

Question 40

If hemoglobin is saturated (1.3 mL of oxygen per gram) and there are 150 grams of hemoglobin per liter of blood, how much oxygen can be delivered to the tissue if cardiac output is 15 liters per minute?

A) 1300 mL O₂/min
B) 1300 g O₂/min
C) 650 g O₂/min
D) 2925 mL O₂/min
E) 2925 g O₂/min

Question 41

Which of the following statements is FALSE regarding a leftward shift in the hemoglobin -oxygen dissociation curve?

A) Affinity for oxygen is increased.
B) It can be caused by an increase in blood pH.
C) It can be caused by an increase in P_CO2.
D) Oxygen loading onto the hemoglobin is increased.
E) Hemoglobin is more saturated at a given P_O2.

Question 42

Where in blood does the conversion of CO₂ to bicarbonate occur?

A) leukocytes
B) plasma
C) erythrocytes
D) platelets
E) capillary endothelial cells

Question 43

In the pulmonary arteries, the partial pressure of oxygen is approximately , and hemoglobin is approximately

A) 80 mm Hg : 90%
B) 60 mm Hg : 80%
C) 100 mm Hg : 98%
D) 25 mm Hg : 50%
E) 40 mm Hg : 75%

Question 44

What is a deficiency of oxygen in the tissues called?

A) hypocapnia
B) hypercapnia
C) apnea
D) hypoxia
E) hypoxemia

Question 45

Which statement best describes the Bohr effect?

A) The Bohr effect refers to the cascading events that must take place in order to chemically remove oxygen from hemoglobin.
B) The Bohr effect refers to a decrease in carbon dioxide concentration which decreases the affinity of hemoglobin for oxygen.
C) The Bohr effect speeds up metabolism and therefore increases the temperature in the body releasing oxygen to the tissues.
D) The Bohr effect refers to the release of a chemical 2,3 BPG from erythrocytes that degrades hemoglobin and releases oxygen.
E) The Bohr effect refers to a decrease in pH which decreases the affinity of hemoglobin for oxygen.

Question 46

In the systemic arteries, the partial pressure of oxygen is approximately , and hemoglobin is approximately _

A) 100 mm Hg : 98%
B) 60 mm Hg : 50%
C) 40 mm Hg : 75%
D) 100 mm Hg : 75%
E) 40 mm Hg : 50%

Question 47

What is rapid shallow breathing called?

A) tachypnea
B) hyperpnea
C) dyspnea
D) eupnea
E) apnea

Question 48

Which of the following statements is FALSE regarding a rightward shift in the hemoglobin -oxygen dissociation curve?

A) Oxygen loading onto hemoglobin is decreased.
B) A rightward shift usually occurs in active tissue.
C) Hemoglobin unloading of oxygen is increased.
D) It can be caused by a decrease in 2,3 -BPG.
E) Affinity for oxygen is decreased.

Question 49

What is labored or difficult breathing called?

A) apnea
B) dyspnea
C) hyperpnea
D) hypopnea
E) eupnea

Question 50

What is the definition of anemia?

A) an increase in P_CO2
B) a decrease in the affinity of hemoglobin for oxygen
C) a decrease in P_O2
D) a decrease in hemoglobin
E) a decrease in the oxygen carrying capacity of the blood

Question 51

The carbamino effect describes a change in the conformation of hemoglobin that is induced by a(n)

A) increase in temperature.
B) decrease in temperature.
C) decrease in pH.
D) increase in pH.
E) increase in CO₂.

Question 52

Which of the following increases oxygen unloading from hemoglobin?

A) decreased metabolism
B) increased blood pH
C) decreased temperature
D) increased oxygen levels in the tissue
E) increased carbon dioxide in the tissue

Question 53

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

A) increase in temperature only
B) increase in plasma pH only
C) increase in 2,3 -BPG (2,3 -bisphosphoglycerate) only
D) both an increase in temperature and an increase in 2,3 -BPG
E) both an increase in temperature and an increase in plasma pH

Question 54

Which of the following will increase the unloading of oxygen within the tissue?

A) increased hydrogen ion concentration only
B) increased P_CO2 only
C) increased body temperature only
D) both increased hydrogen ion concentration and increased body temperature
E) increased hydrogen ion concentration, increased body temperature, and increased P_CO2

Question 55

What is a decrease in oxygen in the blood called?

A) dysnemia
B) hypoxia
C) hypocapnia
D) anemia
E) hypoxemia

Question 56

Which of the following will increase the loading of oxygen onto the hemoglobin molecule within the lungs?

A) increased 2,3 -bisphosphoglycerate (2,3 -BPG)
B) increased body temperature
C) decreased hydrogen ion concentration
D) increased P_CO2
E) decreased pH

Question 57

Which of the following statements about 2,3 -BPG is FALSE?

A) 2,3 -BPG increases the affinity of hemoglobin for oxygen.
B) 2,3 -BPG is produced by red blood cells.
C) 2,3 -BPG is an intermediate of glycolysis.
D) 2,3 -BPG synthesis is inhibited by high levels of oxyhemoglobin.
E) 2,3 -BPG produces a rightward shift in the hemoglobin -oxygen dissociation curve.

Question 58

As oxygen binds to hemoglobin, the of the hemoglobin molecule will change through a process of such that the binding of oxygen is enhanced.

A) amino acid sequence : phosphorylation
B) affinity : negative cooperativity
C) cooperativity : negativity
D) affinity : positive cooperativity
E) cooperativity : positivity

Question 59

Which statement best describes why oxygen is unloaded in tissue that is highly active?

A) As temperature increases, the carbamino effect causes hemoglobin to release oxygen.
B) As temperature increases, the Bohr effect causes hemoglobin to release oxygen.
C) As temperature increases, the affinity for oxygen to hemoglobin increases, allowing more oxygen to be carried to the tissues.
D) Highly active tissues produce more carbon dioxide, which competes for the heme groups in hemoglobin, thereby displacing oxygen.
E) As temperature increases due to increased metabolism, the affinity of hemoglobin for oxygen is decreased.

Question 60

As it leaves the lung in the pulmonary vein, blood is

A) 100% (completely)
B) 108% (supersaturated)
C) 75%
D) 90%
E) 98%

Question 61

Coughing is initiated by _ _ located in the .

A) chemoreceptors : nose and pharynx
B) stretch receptor : trachea
C) irritant receptors : trachea
D) chemoreceptors : trachea
E) irritant receptors : nose and pharynx

Question 62

What is the primary mechanism of carbon dioxide transport in blood?

A) as bicarbonate dissolved in the red blood cells
B) bound to hemoglobin
C) dissolved in the red blood cells
D) dissolved in the plasma
E) as bicarbonate dissolved in the plasma

Question 63

Which of the following nerves has activity during quiet inspiration?

A) phrenic nerve only
B) internal intercostal nerve only
C) external intercostal nerve only
D) both the phrenic nerve and internal intercostal nerves
E) both the phrenic nerve and external intercostal nerves

Question 64

The is the respiratory center that appears to facilitate the transition between inspiration and expiration.

A) pontine respiratory group
B) medullary respiratory group
C) central pattern generator
D) ventral respiratory group
E) dorsal respiratory group

Question 65

Within an erythrocyte, the conversion of CO₂ to bicarbonate is prevented from reaching equilibrium by the

A) presence of hydrogen ions.
B) absence of a nucleus.
C) temperature of the body.
D) efflux of bicarbonate from the erythrocyte via the chloride shift.
E) presence of oxygen.

Question 66

The primary effect of increased P_O2 in the lungs is to cause ventilation -perfusion ratio back to a normal level.

A) vasodilation : decreases
B) bronchodilation : increases
C) vasoconstriction : decreases
D) bronchoconstriction : decreases
E) vasoconstriction : increases

Question 67

During active breathing, bursts of action potentials are observed to occur

A) synchronously in the inspiratory and expiratory motor neurons.
B) exclusively in the expiratory motor neurons.
C) exclusively in the inspiratory motor neurons.
D) simultaneously in the inspiratory and expiratory motor neurons.
E) asynchronously in the inspiratory and expiratory motor neurons.

Question 68

Hyperventilation will cause changes in P_CO2 that are detected by the chemoreceptors which causes a(n)

A) decrease in breathing rate and depth of breathing.
B) increase in depth of breathing only.
C) increase in breathing rate and depth of breathing.
D) increase in breathing rate only.
E) decrease in breathing rate only.

Question 69

During quiet breathing, a person's breathing cycle consists of

A) contraction of inspiratory muscles and relaxation of expiratory muscles.
B) contraction of inspiratory muscles.
C) contraction and relaxation of inspiratory and expiratory muscles.
D) contraction and relaxation of inspiratory muscles.
E) contraction of expiratory muscles.

Question 70

Which of the following best describes a chemoreceptor response to P_O2?

A) Central chemoreceptors respond to only large decreases in P_O2.
B) Central chemoreceptors do not respond to changes in P_O2.
C) Peripheral chemoreceptors respond to oxyhemoglobin.
D) Peripheral chemoreceptors respond to small changes in P_O2.
E) Peripheral chemoreceptors respond only indirectly to P_O2.

Question 71

Chemoreceptors respond primarily to changes in P_CO2 indirectly by its effect on

A) 2,3 -diphosphoglycerate (2,3 -DPG) concentration.
B) P_O2.
C) hydrogen ion concentration.
D) lactic acid concentration.
E) hemoglobin concentration.

Question 72

The hydrogen ions released by the dissociation of carbonic acid are buffered by their

A) binding to hemoglobin.
B) active transport out of the erythrocyte.
C) binding to DNA within the nucleus.
D) transport into the erythrocyte as sodium ions move out.
E) transport out of the erythrocyte as a sodium ion moves in.

Question 73

Which statement best describes how people die of carbon monoxide poisoning?

A) Carbon monoxide causes decompression sickness which can lead to death.
B) Carbon monoxide is toxic because it readily picks up oxygen to produce carbon dioxide, causing acidosis and eventual death.
C) Carbon monoxide is toxic because it binds more readily to hemoglobin than oxygen, thereby decreasing the oxygen carrying capacity of blood.
D) As the carbon dioxide content of blood increases, a phenomenon known as the Haldane effect converts the excess carbon dioxide to carbon monoxide until it reaches toxic levels.
E) Carbon monoxide causes the carbamino effect where carbon dioxide is stripped of an oxygen, producing carbon monoxide.

Question 74

Central chemoreceptors are neurons in the medulla that respond directly to changes in

A) cerebrospinal fluid P_O2.
B) cerebrospinal fluid pH.
C) blood pH and P_O2.
D) cerebrospinal fluid P_O2 and pH.
E) blood pH.

Question 75

A local bronchodilation within the alveolus will result in a(n) in the ventilation -perfusion ratio in that region. A vasoconstriction of pulmonary arteriole diameter will result in a(n) in the ventilation -perfusion ratio in that region.

A) decrease : increase
B) increase : increase
C) lack of change : increase
D) decrease : decrease
E) increase : decrease

Question 76

The presence of bicarbonate ions in the blood has an important direct effect, aside from the transport of CO₂, that involves

A) altering the activity of carbonic anhydrase.
B) altering the activity of several receptors.
C) maintaining acid -base balance.
D) altering the affinity of hemoglobin for oxygen.
E) stimulating the proliferation of alveolar epithelial cells.

Question 77

Peripheral chemoreceptors are specialized cells in contact with arterial blood that respond directly to changes in blood

A) pH.
B) P_O2.
C) P_CO2.
D) P_CO2 and P_O2.
E) P_O2, pH, and P_CO2.

Question 78

In the model for quiet breathing, expiration is induced by

A) activation of inspiratory neurons in the ventral respiratory center.
B) abrupt termination of inspiration.
C) activation of expiratory neurons in the dorsal respiratory center.
D) activation of inspiratory neurons in the dorsal respiratory center.
E) activation of expiratory neurons in the ventral respiratory center.

Question 79

A decrease in P_CO2 within the lung will result in a in the bronchioles.

A) vasodilation : weak bronchodilation
B) weak vasodilation : bronchoconstriction
C) weak vasoconstriction : bronchodilation
D) vasoconstriction : lack of change
E) lack of change : weak bronchoconstriction

Question 80

The Haldane effect describes the increase in the affinity of hemoglobin for CO₂ in the presence of a lowered

A) P_CO2.
B) pH.
C) concentration of bicarbonate (HCO₃ ^-).
D) P_O2.
E) temperature.