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

Question 1

Which of the following best describes a chemoreceptor response to PO2?

A)Peripheral chemoreceptors respond to small changes in PO2.
B)Peripheral chemoreceptors respond only indirectly to PO2.
C)Central chemoreceptors do not respond to changes in PO2.
D)Central chemoreceptors respond to only large decreases in PO2.
E)Peripheral chemoreceptors respond to oxyhemoglobin.

Answer 1

C

Question 2

What percentage of air is oxygen?

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

Answer 2

E

Question 3

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

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

Answer 3

E

Question 4

Chemoreceptors respond primarily to changes in PCO2 indirectly by its effect on

A)hemoglobin concentration.
B)2,3- diphosphoglycerate (2,3- DPG)concentration.
C)hydrogen ion concentration.
D)lactic acid concentration.
E)PO2.

Question 5

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

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

Question 6

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

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

Question 7

What percentage of air is carbon dioxide?

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

Question 8

A decrease in the affinity of oxygen for hemoglobin is reflected as a _ shift in the hemoglobin- oxygen dissociation curve, which would facilitate the _ of oxygen.

A)rightward : loading
B)rightward : unloading
C)leftward : loading
D)neutral : loading
E)leftward : unloading

Question 9

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

Question 10

Which statement best describes the effect on the body due to pH changes either above or below the normal range?

A)Changes in pH can denature proteins that serve as enzymes and receptors throughout the body, resulting in widespread effects on the body.
B)Changes in pH destroy the nephrons of the kidney, making kidney failure is inevitable.
C)Changes in pH out of the normal range are normal and will not have any detrimental effects on the body.
D)pH ranges vary throughout the body; therefore, blood pH has no detrimental effects on the body as it changes pH.
E)Changes in pH can only lower pH causing acidosis, meaning organs deteriorate due to high levels of acid.

Question 11

What is the partial pressure of nitrogen if it accounts for 20% of a mixed gas with a total pressure of 1000 mm Hg?

A)200 mm Hg
B)10 mm Hg
C)0 mm Hg
D)20 mm Hg
E)100 mm Hg

Question 12

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

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

Question 13

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

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

Question 14

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 life- threatening situation.

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

Question 15

During intense exercise, the metabolic activity of muscle causes in the partial pressure of oxygen in the tissue, the movement of oxygen into the tissue.

A)a decrease : facilitating
B)no change : facilitating
C)a decrease : reducing
D)an increase : reducing
E)an increase : facilitating

Question 16

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

Question 17

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

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

Question 18

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 19

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in systemic arteries?

A)80 mm Hg
B)46 mm Hg
C)100 mm Hg
D)40 mm Hg
E)160 mm Hg

Question 20

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in alveoli?

A)40 mm Hg
B)80 mm Hg
C)160 mm Hg
D)46 mm Hg
E)100 mm Hg

Question 21

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

A)pH.
B)PO2.
C)PCO2.
D)PCO2 and PO2.
E)PO2, pH, and PCO2.

Question 22

A change in the ratio of bicarbonate to carbon dioxide concentration in the blood will

A)change blood pH.
B)cause a bronchodilation.
C)change blood chloride concentration.
D)change blood potassium concentration.
E)cause a vasodilation of systemic arterioles.

Question 23

Hypoventilation would lead to a(n)within the systemic arteries.

A)selective decrease in PO2
B)selective increase in PO2
C)decrease in PO2 and increase in PCO2
D)increase in PO2 and decrease in PCO2
E)selective decrease in PCO2

Question 24

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

Question 25

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

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

Question 26

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 27

Assuming resting conditions at sea level, what is the partial pressure of oxygen in alveoli?

A)160 mm Hg
B)40 mm Hg
C)80 mm Hg
D)46 mm Hg
E)100 mm Hg

Question 28

What is the definition of anemia?

A)a decrease in PO2
B)a decrease in the affinity of hemoglobin for oxygen
C)an increase in PCO2
D)a decrease in hemoglobin
E)a decrease in the oxygen carrying capacity of the blood

Question 29

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

A)It can be caused by an increase in blood pH.
B)Oxygen loading onto the hemoglobin is increased.
C)It can be caused by an increase in PCO2.
D)Affinity for oxygen is increased.
E)Hemoglobin is more saturated at a given PO2.

Question 30

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

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

Question 31

Bicarbonate is an important buffer in blood and its concentration is regulated by the

A)pancreas.
B)heart.
C)lungs.
D)kidneys.
E)liver.

Question 32

A decrease in PCO2 within the lung will result in a in the pulmonary vasculature and a in the bronchioles.

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

Question 33

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

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

Question 34

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

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

Question 35

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 36

What is a deficiency of oxygen in the tissues called?

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

Question 37

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

A)increased hydrogen ion concentration only
B)increased PCO2 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 PCO2

Question 38

At sea level the air pressure which equals 1 atmosphere is

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

Question 39

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

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

Question 40

What percentage of oxygen is transported by hemoglobin?

A)98.5%
B)5%
C)75%
D)86%
E)1)5%

Question 41

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

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

Question 42

Hyperventilation will cause changes in PCO2 that are detected by the chemoreceptors which causes a(n)

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

Question 43

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

Question 44

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)decreased pH
E)increased PCO2

Question 45

Which statement best describes the Bohr effect?

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

Question 46

Assuming resting conditions at sea level, what is the partial pressure of oxygen in systemic veins?

A)160 mm Hg
B)100 mm Hg
C)46 mm Hg
D)40 mm Hg
E)80 mm Hg

Question 47

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

Question 48

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

Question 49

What is the most common cause of pulmonary edema?

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

Question 50

Hyperventilation would lead to a(n)_ within the systemic arteries.

A)selective decrease in PCO2
B)selective decrease in PO2
C)increase in PO2 and decrease in PCO2
D)selective increase in PO2
E)decrease in PO2 and increase in PCO2

Question 51

Assuming resting conditions at sea level, what is the partial pressure of oxygen in pulmonary arteries?

A)100 mm Hg
B)160 mm Hg
C)40 mm Hg
D)80 mm Hg
E)46 mm Hg

Question 52

As it leaves the lung in the pulmonary vein, blood is saturated with oxygen.
A)108% (supersaturated)

A)75%
B)100% (completely)
B)98%
E)90%

Question 53

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

Question 54

Which of the following increases oxygen unloading from hemoglobin?

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

Question 55

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

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

Question 56

A decrease in the affinity of hemoglobin for oxygen caused by the binding of carbon dioxide to hemoglobin is described by the

A)carbamino effect.
B)Henderson- Hasselbalch effect.
C)respiratory quotient.
D)Bohr effect.
E)Haldane effect.

Question 57

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

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

Question 58

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

Question 59

Each on the hemoglobin subunit is capable of binding an oxygen molecule, thereby allowing _ _ oxygen to bind with one hemoglobin molecule.

A)globin : four
B)heme : three
C)heme : four
D)free iron : one
E)globin : three

Question 60

Respiratory acidosis can occur during

A)hyperventilation.
B)hypocapnia.
C)the Haldane effect.
D)hyperpnea.
E)hypoventilation.

Question 61

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

A)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.
B)Carbon monoxide is toxic because it readily picks up oxygen to produce carbon dioxide, causing acidosis and eventual death.
C)Carbon monoxide causes decompression sickness which can lead to death.
D)Carbon monoxide causes the carbamino effect where carbon dioxide is stripped of an oxygen, producing carbon monoxide.
E)Carbon monoxide is toxic because it binds more readily to hemoglobin than oxygen, thereby decreasing the oxygen carrying capacity of blood.

Question 62

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

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

Question 63

The respiratory quotient is calculated as the

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

Question 64

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 65

What is labored or difficult breathing called?

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

Question 66

In the model for quiet breathing, expiration is induced by

A)activation of expiratory 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 ventral respiratory center.
E)activation of inspiratory neurons in the dorsal respiratory center.

Question 67

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

Question 68

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

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

Question 69

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

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

Question 70

Which of the following causes a decrease in the PO2 of air as it enters the conducting zone of the lungs?

A)the increasing PCO2
B)decreasing alveolar PO2
C)warming of the air
D)the consumption of oxygen
E)humidifying the air

Question 71

Assuming resting conditions at sea level, what is the partial pressure of carbon dioxide in pulmonary veins?

A)80 mm Hg
B)160 mm Hg
C)100 mm Hg
D)46 mm Hg
E)40 mm Hg

Question 72

Respiratory acidosis will result from a(n)

A)decrease in blood CO2 concentration.
B)increase in blood CO2 concentration.
C)increase in carbon monoxide.
D)increase in blood bicarbonate.
E)decrease in blood bicarbonate.

Question 73

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

A)2,3- bisphosphoglycerate (2,3- BPG)
B)temperature
C)pH
D)PO2
E)PCO2

Question 74

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

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

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

Question 76

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

A)blood pH.
B)cerebrospinal fluid PO2 and pH.
C)cerebrospinal fluid pH.
D)blood pH and PO2.
E)cerebrospinal fluid PO2.

Question 77

Assuming resting conditions at sea level, what is the partial pressure of oxygen in pulmonary veins?

A)80 mm Hg
B)46 mm Hg
C)40 mm Hg
D)100 mm Hg
E)160 mm Hg

Question 78

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

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

Question 79

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

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

Question 80

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

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