Deck 42: Gas Exchange and Circulation

Question 1

The air pressure in Denver, Colorado, is about 83 percent of the air pressure in Miami Beach, which is at about sea level. Given that the air pressure in Miami Beach is 760 mm Hg and oxygen makes up 21 percent of the air in Miami Beach, what are the percentage of oxygen and the partial pressure of oxygen in Denver?

A) 21 percent; 21 mm Hg
B) 21 percent; 132 mm Hg
C) 17.4 percent; 132 mm Hg
D) 17.4 percent; 21 mm Hg

Answer 1

B

Question 2

When the air in a testing chamber is specially mixed so that its oxygen content is 10 percent and its overall air pressure is 400 mm Hg, then PO2 is ________.

A) 400 mm Hg
B) 82 mm Hg
C) 40 mm Hg
D) 21 mm Hg
E) 4 mm Hg

Answer 2

C

Question 3

At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still composed of 21 percent oxygen, then the partial pressure of oxygen at this altitude is about ________.

A) 0 mm Hg
B) 80 mm Hg
C) 160 mm Hg
D) 380 mm Hg
E) 760 mm Hg

Answer 3

B

Question 4

Under identical atmospheric conditions, freshwater ________.

A) has more oxygen than seawater
B) has less oxygen than seawater
C) can hold 10-40 times more carbon dioxide than air
D) can hold 10-40 times more oxygen than air

Question 5

Determine the rate of diffusion (cm3/min or mL/min) in the gas-exchange organ of an air-breathing animal where the area for gas exchange in the lung is 2 cm2, the diffusion constant is 0.08 cm2/min, the PO2 (partial pressure of oxygen) of the air in the lung is 140 mm Hg, the PO2 in blood flowing into the lung is 90 mm Hg, and the thickness of the gas exchange membrane is 0.0001 cm.

A) 80,000
B) 125
C) 32,000
D) 10,00,000

Question 6

Countercurrent exchange in the fish gill helps to maximize ________.

A) endocytosis
B) blood pressure
C) extraction of oxygen from the water
D) active transport
E) osmosis

Question 7

A rabbit taken from a meadow near sea level and moved to a meadow high on a mountainside would have some trouble breathing. Why?

A) The percentage of oxygen in the air at high elevations is lower than at sea level.
B) The percentage of oxygen in the air at high elevations is higher than at sea level.
C) The partial pressure of oxygen in the air at high elevations is lower than at sea level.
D) The partial pressure of oxygen in the air at high elevations is higher than at sea level.

Question 8

Gas exchange is more difficult for aquatic animals with gills than for terrestrial animals with lungs because ________.

A) water is less dense than air
B) water contains much less oxygen per unit volume than air
C) gills have less surface area than lungs
D) gills allow only unidirectional transport
E) gills collapse in air

Question 9

Which of the following respiratory systems is NOT closely associated with the blood supply?

A) the lungs of a vertebrate
B) the gills of a fish
C) the tracheal system of an insect
D) the skin of an earthworm

Question 10

At an atmospheric pressure of 870 mm Hg with 21 percent oxygen, the partial pressure of oxygen is ________.

A) 100 mm Hg
B) 127 mm Hg
C) 151 mm Hg
D) 182 mm Hg
E) 219 mm Hg

Question 11

Carbon dioxide levels in the blood and in cerebrospinal fluid affect pH of these fluids. This enables the organism to sense a disturbance in gas levels as ________.

A) the brain directly measures and monitors oxygen levels and causes breathing changes accordingly
B) neurons in contact with cerebrospinal fluid monitor pH and use this measure to control breathing
C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide
D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing
E) the medulla oblongata is able to control the concentration of bicarbonate ions in the blood

Question 12

Atmospheric pressure at sea level is equal to a column of 760 mm Hg. Oxygen makes up 21 percent of the atmosphere by volume. The partial pressure of oxygen (PO2) in such conditions is ________.

A) 160 mm Hg
B) 16 mm Hg
C) 120/75
D) 21/760
E) 760/21

Question 13

What is the correct order of processes involving the movement of oxygen from the environment to mitochondria in vertebrates?

A) ventilation, circulation, cellular respiration
B) circulation, ventilation, cellular respiration
C) diffusion in tissues, cellular respiration, diffusion at respiratory surface
D) ventilation, diffusion in tissues, circulation
E) circulation, cellular respiration, diffusion in tissues

Question 14

If other factors are equal, which of the following environments would have the highest level of dissolved oxygen?

A) warm, salty water at low elevation
B) cool, salty water at low elevation
C) warm freshwater at high elevation
D) cool freshwater at high elevation
E) cool freshwater at low elevation

Question 15

Breathing is primarily regulated by ________.

A) erythropoietin levels in the blood
B) the concentration of red blood cells
C) hemoglobin levels in the blood
D) carbon dioxide concentration and pH sensors
E) the lungs and the larynx

Question 16

Countercurrent exchange is evident in the flow of ________.

A) water across the gills of a fish and the blood within those gills
B) blood in the dorsal vessel of an insect and that of air within its tracheae
C) air within the primary bronchi of a human and the blood within the pulmonary veins
D) water across the skin of a frog and the blood flow within the ventricle of its heart

Question 17

The sun shining on a tidal pool during a hot day heats the water. As some water evaporates, the pool becomes saltier, causing ________.

A) an increase in its carbon dioxide content
B) a decrease in its oxygen content
C) an increase in its ability to sustain aerobic organisms
D) a decrease in the water's density

Question 18

In which location would you expect the oxygen concentration to be the lowest?

A) the environment
B) the blood
C) the lungs
D) within tissues
E) the heart

Question 19

Which of the following statements comparing respiration in fish and in mammals is correct?

A) The respiratory medium for fish carries more oxygen than the respiratory medium of mammals.
B) A countercurrent exchange mechanism between the respiratory medium and blood flow is seen in mammals but not in fish.
C) The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional.
D) In blood, oxygen is primarily transported by plasma in fish, but by red blood cells in mammals.

Question 20

Which of the following best describes the process of ventilation?

A) the movement of oxygen gas through the blood of the circulatory system
B) the movement of carbon dioxide gas through the blood of the circulatory system
C) the movement of the respiratory medium past the respiratory surface
D) the diffusion of gases into and out of the circulatory system
E) the diffusion of gases into and out of tissues where cellular respiration occurs

Question 21

What adaptations are observed in trachea and lungs to reduce water loss?

A) A countercurrent exchange system reduces water loss in animals with either trachea or lungs.
B) The location of the trachea and lungs (inside of the body) reduces water loss.
C) Trachea and lungs secrete specialized oxygen-carrying chemicals to reduce water loss.
D) Limbs are used by animals with trachea or lungs to move water over these structures.

Question 22

A significant increase in the amount of interstitial fluid surrounding the capillary beds of a human's lungs will cause ________.

A) an increase in the amount of carbon dioxide moving from the blood to the lungs
B) an increase in the amount of oxygen moving from the lungs into the blood
C) a decrease in the amount of oxygen moving from the lungs into the blood
D) an increase of pressure that would cause the capillary beds to burst
E) a decrease in the amount of work needed for effective ventilation of the lungs

Question 23

The exhalation of air from human lungs is driven by ________.

A) a decrease in the volume of the thoracic cavity with an associated increase in thoracic pressure
B) a decrease in the residual volume of the lungs
C) the contraction of the diaphragm
D) the closure of the epiglottis
E) the expansion of the rib cage

Question 24

When you are jogging, your muscles are using more oxygen and releasing more carbon dioxide into the blood than when you are at home on the couch. Which of the following would occur during your jog?

A) Blood pH would become more basic.
B) The concentration of bicarbonate ions (HCO3−) in the blood would decrease.
C) The medullary respiratory center would detect rising carbon dioxide levels.
D) The volume of the dead air space would decrease.

Question 25

As a person goes from rest to full-effort exercise, there is an increase in the ________.

A) tidal volume
B) vital capacity
C) residual volume
D) total lung capacity

Question 26

What would be the consequences if we were to reverse the direction of water flow over the gills of a fish, moving water inward past the operculum, past the gills, then out of the mouth? This reversal of water flow would ________.

A) reduce the efficiency of gas exchange
B) change the exchange of gases in the body from carbon dioxide out and oxygen in to carbon dioxide in and oxygen out
C) increase the efficiency of gas exchange

Question 27

Air-breathing insects carry out gas exchange ________.

A) in their specialized external gills
B) in their specialized internal gills
C) in the alveoli of their lungs
D) across the finest branches of the trachea and cell membranes
E) across all parts of their thin cuticular exoskeleton

Question 28

When you hold your breath, which of the following blood gas changes first leads to the urge to breathe?

A) rising oxygen
B) falling oxygen
C) rising carbon dioxide
D) falling carbon dioxide

Question 29

To become bound to hemoglobin for transport in a mammal, atmospheric molecules of oxygen must cross ________.

A) zero membranes-oxygen binds directly to hemoglobin, a protein dissolved in the plasma of the blood
B) one membrane-that of the lining in the lungs-and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
C) two membranes-in and out of the cells lining the lung-and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
D) four membranes-in and out of the cells lining the lung, in and out of the endothelial cell lining an alveolar capillary-and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
E) five membranes-in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary, and into the red blood cell-to bind with hemoglobin

Question 30

The one-way flow of air along parabronchi makes what type of gas-exchange mechanism possible, at least theoretically?

A) the same as that occurring in fish gills
B) the same as that occurring in insect tracheae
C) the same as that occurring in mammalian lungs
D) the same as that occurring in echinoderm skin gills

Question 31

In what way does hemoglobin act as a buffer against changes in blood pH?

A) Subsequent binding of oxygen is drastically reduced after the first one is bound.
B) Hemoglobin binds some of the excess protons released by carbonic acid.
C) Hemoglobin produces protons or hydroxide ions as needed to alter the blood pH.
D) Hemoglobin removes excess protons from the red blood cells so that they can be excreted through the kidneys.

Question 32

Some animals have no gills when young but then develop gills that grow larger as the animal grows larger. What is the reason for this increase in gill size?

A) The young of these animals are much more active than the adult, which leads to a higher BMR (basal metabolic rate) and, therefore, a higher need for oxygen.
B) Relative to their volume, the young have more surface area across which they can transport all the oxygen they need.
C) The young have a higher basal metabolic rate.
D) Relative to their surface area, the young have more body volume in which they can store oxygen for long periods of time.

Question 33

In mammals, gas exchange between the atmosphere and the pulmonary blood occurs in the ________.

A) trachea
B) larynx
C) bronchi
D) bronchioles
E) alveoli

Question 34

Fick's law of diffusion describes the factors that influence the diffusion of respiratory gases across biological membranes like gills and lungs. Diffusion rate = k × A × (P2 − P1)/D. Natural selection is LEAST likely to act upon which variable in Fick's law?

A) A
B) k
C) P2 − P1
D) D

Question 35

Birds generate a lot of heat, especially during flight. Yet the adipose tissue under their skin and the feathers atop their skin make it difficult to eliminate excess heat across the skin. Which of the following alternatives can absorb body heat and eliminate it from the bird most effectively?

A) air in the air sacs
B) lymph in the lymphatic vessels
C) blood in the vessels
D) blood in the heart
E) urine in the bladder

Question 36

The movement of air along parabronchi is most similar to the movement of ________.

A) air in the lungs of other amniotes
B) food/waste in a gastrovascular cavity
C) a mouse passing through the digestive system of a snake
D) the frog tongue during feeding
E) air in lungs of terrestrial amphibians

Question 37

If the inner lining of the air sacs is neither thin nor highly vascularized, then what can be inferred about the air sacs?

A) They must not belong to the respiratory system.
B) They cannot be derived from endoderm.
C) They are not efficient sites of gas exchange between air and blood.
D) They must obtain nutrition from some source other than the bloodstream.
E) They cannot effectively moisturize the air before it reaches the lungs.

Question 38

Some bird bones are hollow rather than honeycombed. The hollow bones mostly contain air sacs. The replacement of bone marrow with air sacs is properly understood as an adaptation that ________.
1) reduces the weight of the bird
2) facilitates flight
3) eliminates the functions of bone marrow

A) only 1
B) only 2
C) only 3
D) 1 and 2
E) 1, 2, and 3

Question 39

Which type of bird is most likely to benefit from air sacs that reduce its weight?

A) birds, such as geese, which migrate great distances
B) birds that chip away wood, such as woodpeckers
C) diving birds
D) birds that rip apart prey, such as hawks and eagles

Question 40

Air rushes into the lungs of humans during inhalation because ________.

A) the rib muscles and diaphragm contract, increasing the lung volume and decreasing the pressure within the lungs
B) the volume of the alveoli increases as smooth muscles contract
C) gas flows from a region of lower pressure to a region of higher pressure
D) pulmonary muscles contract and pull on the outer surface of the lungs
E) a positive respiratory pressure is created when the diaphragm relaxes

Question 41

Most of the carbon dioxide produced by humans is ________.

A) converted to bicarbonate ions by carbonic anhydrase, an enzyme in red blood cells
B) bound to hemoglobin
C) transported in the erythrocytes as carbonic acid
D) simply dissolved in the plasma
E) bicarbonate ions bound to hemoglobin

Question 42

Which of the following events would be predicted by the Bohr shift effect as the amount of carbon dioxide released from your tissues into the blood capillaries increases? The amount of oxygen in ________.

A) arterial blood would increase
B) arterial blood would decrease
C) venous blood would increase
D) venous blood would decrease

Question 43

Which of the following reactions prevails in red blood cells traveling through alveolar capillaries? (Hb = hemoglobin)

A) Hb + 4 O2 → Hb(O2)4
B) Hb(O2)4 → Hb + 4 O2
C) CO2 + H2O → H2CO3
D) H2CO3 → H+ + HCO3−
E) Hb + 4 CO2 → Hb(CO2)4

Question 44

Which component of blood is responsible for the formation of blood clots?

A) red blood cells
B) white blood cells
C) platelets
D) all blood cells
E) None of the above form blood clots.

Question 45

Compared with the interstitial fluid that bathes active muscle cells, blood reaching these muscle cells in arteries has a ________.

A) higher PO2
B) higher PCO2
C) greater bicarbonate concentration
D) lower pH
E) lower osmotic pressure

Question 46

In which of the following organisms does blood flow from the lungs to the heart before circulating through the rest of the body?

A) annelids
B) mollusks
C) fishes
D) frogs
E) insects

Question 47

In what way does hemoglobin act as a buffer against changes in blood pH?

A) Subsequent binding of oxygen is drastically reduced after the first one is bound.
B) Hemoglobin binds some of the excess protons released by carbonic acid.
C) Hemoglobin produces protons or hydroxide ions as needed to alter the blood pH.
D) Hemoglobin removes excess protons from the red blood cells so that they can be excreted through the kidneys.

Question 48

Based on the accompanying figure, showing fetal (A) and adult (B) oxygen-hemoglobin saturation curves, which of the following conclusions is TRUE?

A) The mother binds oxygen with greater affinity than the fetus.
B) Adult saturation occurs at lower partial pressures of oxygen than fetal saturation does.
C) At 50 percent saturation, fetal blood will have a higher affinity for oxygen than adult blood will.
D) As the partial pressure of oxygen increases, adult hemoglobin approaches saturation faster than fetal hemoglobin does.

Question 49

Complete the statement correctly. Fetal hemoglobin ________.

A) binds more carbon dioxide molecules than adult hemoglobin
B) is better able to release oxygen than is adult hemoglobin
C) has a higher affinity for oxygen than does adult hemoglobin
D) is better able to release carbon dioxide than is adult hemoglobin
E) has a higher affinity for carbon dioxide than does adult hemoglobin

Question 50

Which of the following develops the greatest pressure on the blood in the mammalian aorta?

A) systole of the left atrium
B) diastole of the right ventricle
C) systole of the left ventricle
D) diastole of the right atrium
E) diastole of the left atrium

Question 51

The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in ________.

A) the partial pressure of oxygen
B) the partial pressure of carbon monoxide
C) hemoglobin concentration
D) temperature
E) pH

Question 52

The oxygen content of water increases linearly with an increase in oxygen partial pressure, whereas the oxygen content of blood increases in a sigmoidal (S-shaped) fashion. Why?

A) Carbonic anhydrase contributes to carbon dioxide release in blood, but not water.
B) The Bohr shift is stronger in water than in blood.
C) Hemoglobin shows cooperative oxygen binding.
D) Oxygen is transported equally by hemoglobin and blood plasma.

Question 53

The circulatory systems of bony fishes, rays, and sharks are most similar to ________.

A) those of birds, with a four-chambered heart
B) the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber
C) those of reptiles, with one pumping chamber driving blood flow to a gas-exchange organ, and a different pumping chamber driving blood to the rest of the circulation
D) those of sponges, where gas exchange in all cells occurs directly with the external environment
E) those of humans, where there are four pumping chambers to drive blood flow

Question 54

A large increase in albumin concentration in the plasma of a dog would result in which of the following?

A) an increase in blood volume and a decrease in lymph volume
B) a decrease in blood volume and an increase in lymph volume
C) an increase in blood volume and an increase in lymph volume
D) a decrease in blood volume and a decrease in lymph volume

Question 55

Altitude sickness occurs when a hiker ascends to altitudes where the density of oxygen is low. Carbonic anhydrase inhibitors cause less movement of carbonic acid toward carbon dioxide production and are used as a prophylactic treatment of altitude sickness. How does this treatment decrease the symptoms of high altitude sickness?

A) The resulting rise in pH increases respiration rate.
B) Excess bicarbonate ions are excreted in the urine and the resulting loss of blood pressure increases respiration rate.
C) An increase in blood acidity leads to an increase in ventilation.
D) An increase in bicarbonate ions in the blood stimulates the production of more red blood cells.
E) The excess bicarbonate ions in the blood increase the affinity of hemoglobin for oxygen.

Question 56

Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have ________.

A) an open circulatory system
B) a closed circulatory system
C) a gastrovascular cavity
D) branched tracheae
E) hemolymph

Question 57

An increase in blood carbon dioxide content causes hemoglobin to ________.

A) release all bound carbon dioxide molecules
B) bind more oxygen molecules
C) denature
D) increase its binding of H+
E) give up more of its oxygen molecules

Question 58

To increase the output of the heart, what adjustments are made in the circulatory system?
1) an increase in heart rate
2) an increase in stroke volume of the heart
3) a reduced blood flow to the brain

A) only 1
B) only 2
C) only 3
D) 1 and 2
E) 1, 2, and 3

Question 59

The vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the ________.

A) amphibians
B) birds
C) fishes
D) mammals
E) reptiles

Question 60

You are a physician, and you are seeing a patient who complains of abnormal fatigue during exercise. You find that the immediate problem is a buildup of carbon dioxide in the tissues. What is the most likely cause?

A) abnormally shaped platelets
B) abnormal carbonic anhydrase
C) abnormal hemoglobin
D) not enough hemoglobin

Question 61

Damage to the sinoatrial node in humans ________.

A) is a major contributor to heart attacks
B) would block conductance between the bundle branches and the Purkinje fibers
C) would have a negative effect on peripheral resistance
D) would disrupt the rate and timing of cardiac muscle contractions
E) would have a direct effect on blood pressure monitors in the aorta

Question 62

A patient with a blood pressure of 120/75, a pulse rate of 70 beats/minute, a stroke volume of 70 mL/beat (milliliters per beat), and a respiratory rate of 25 breaths/minute will have a cardiac output of ________.

A) 70 mL/minute
B) 1000 mL/minute
C) 1750 mL/minute
D) 2800 mL/minute
E) 4900 mL/minute

Question 63

Heart rate will increase in the presence of increased ________.

A) low-density lipoproteins
B) immunoglobulins
C) erythropoietin
D) epinephrine
E) platelets

Question 64

A stroke volume of 70 mL/beat in a heart with a pulse of 72 beats per minute results in a cardiac output of about ________.

A) 5 liters per minute
B) 50 milliliters per minute
C) 0.5 liters per minute
D) 50 liters per minute
E) 500 liters per minute

Question 65

One feature that amphibians and humans have in common is ________.

A) the number of heart chambers
B) the type of gas-exchange tissues
C) a complete separation of circuits for circulation
D) the number of circuits for circulation
E) a low blood pressure in the systemic circuit

Question 66

The fluid that is moved by in the circulatory system of a typical arthropod is ________.

A) digestive juices
B) hemolymph
C) blood plasma
D) cytosol

Question 67

A species that has a normal resting systolic blood pressure of greater than 260 mm Hg is likely to be ________.

A) an animal that is small and compact, without the need to pump blood very far from the heart
B) an animal with abundant lipid storage
C) a species that has very wide diameter veins
D) an animal that has a very long distance between its heart and its brain
E) an animal that makes frequent, quick motions

Question 68

Among the following choices, which organism likely has the highest systolic pressure?

A) mouse
B) rabbit
C) human
D) hippopotamus
E) giraffe

Question 69

Circulatory systems compensate for ________.

A) temperature differences between the lungs and the active tissue
B) the slow rate at which diffusion occurs over large distances
C) the problem of communication systems involving only the nervous system
D) the need to cushion animals from trauma
E) the need that fetal organisms have for maintaining an optimal body temperature

Question 70

What type of blood vessels has the slowest velocity of blood flow?

A) arteries
B) arterioles
C) veins
D) capillaries

Question 71

The velocity of blood flow is the lowest in capillaries because ________.

A) the capillary walls are not thin enough to allow oxygen to exchange with the cells
B) the capillaries have internal valves that slow the flow of blood
C) the diastolic blood pressure is too low to deliver blood to the capillaries at a high flow rate
D) the systemic capillaries are supplied by the left ventricle, which has a lower cardiac output than the right ventricle
E) the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system

Question 72

Blood returning to the mammalian heart in a pulmonary vein drains first into the ________.

A) vena cava
B) left atrium
C) right atrium
D) left ventricle
E) right ventricle

Question 73

An animal has a cardiac output of 40 mL/min (milliliters per minute) and a stroke volume of 5 mL. What is its heart rate?

A) 8 beats/minute
B) 200 beats/minute
C) 12.5 beats/minute
D) Heart rate cannot be determined with only these two variables.

Question 74

The blood pressure is lowest in the ________.

A) aorta
B) arteries
C) arterioles
D) left ventricle of the heart
E) vena cava

Question 75

Which of the four muscular chambers of the human heart directly propels blood into the pulmonary circulation?

A) right atrium
B) right ventricle
C) left atrium
D) left ventricle

Question 76

The aortic valve of the mammalian heart ________.

A) is the route by which blood flows from the atria to the ventricles
B) is found on the right side of the heart
C) is the attachment site where the pulmonary veins empty into the heart
D) prevents backflow of blood in the aorta
E) is located where the anterior and posterior venae cavae empty into the heart

Question 77

Which of the following is the correct sequence of blood flow in birds and mammals?

A) left ventricle → aorta → lungs → systemic circulation
B) vena cava → right atrium → right ventricle → pulmonary vein
C) pulmonary vein → left atrium → left ventricle → pulmonary circuit
D) vena cava → right atrium → right ventricle → pulmonary artery
E) right atrium → pulmonary artery → left atrium → ventricle

Question 78

An anthropologist discovers the fossilized heart of an extinct animal. The evidence indicates that the organism's heart was large, was well formed, and had four chambers, with no connection between the right and left sides. A reasonable conclusion supported by these observations is that the ________.

A) animal had evolved from birds
B) animal was endothermic and had a high metabolic rate
C) animal was most closely related to alligators and crocodiles
D) animal was likely an invertebrate animal
E) species had little to no need to regulate blood pressure

Question 79

Atria contract ________.

A) at the beginning of atrial diastole
B) during atrial diastole
C) immediately after ventricular systole
D) during atrial systole

Question 80

Pulse is a direct measure of ________.

A) blood pressure
B) stroke volume
C) cardiac output
D) heart rate
E) breathing rate