Deck 44: Gas Exchange and Circulation

Question 1

Which of the following statements supports the hypothesis that the bidirectional gas flow occurring in humans (air goes in and out through the same passages)is less efficient than the unidirectional flow in fish?

A)Bidirectional flow in humans does not take advantage of countercurrent exchange.
B)About one-third of the air in human lungs is trapped in "dead space" where gas exchange with the circulation cannot occur.
C)None of the above are true.
D)Both A and B are true.

Answer 1

C

Question 2

Which of the following is NOT a feature of gas exchange in the respiratory system of birds?

A)The exchange of gases between parabronchi and blood is in a countercurrent direction.
B)The flow of air through the lungs is one way.
C)The dead space within the respiratory system is small compared to that in mammals.
D)Gas exchange occurs during both inhalation and exhalation.

Answer 2

A

Question 3

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

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

Answer 3

B

Question 4

Marine crabs have internal gills covered by an exoskeleton,and,because their whole body is covered by exoskeleton,they cannot expand their body enough to generate much negative pressure within the gill chambers to draw water in over their gills.Which of the following would serve to increase the efficiency of gas exchange by marine crabs?

A)a countercurrent exchange system
B)oxygen-carrying molecules in the blood
C)movement of limbs or other structures to create a current over the gills
D)all of the above
E)only B and C

Question 5

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

A)Carbonic anhydrase contributes to CO₂ release in blood,but not water.
B)The Bohr shift is stronger in water than in blood.
C)Hemoglobin shows cooperative oxygen binding.
D)All of the above answers apply.

Question 6

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.
E)All of the above answers apply.

Question 7

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?

A)The amount of oxygen in arterial blood would increase.
B)The amount of oxygen in arterial blood would decrease.
C)The amount of oxygen in venous blood would increase.
D)The amount of oxygen in venous blood would decrease.
E)More than one of the above is true.

Question 8

In the countercurrent exchange respiratory system of fish,which of the following would not be expected?

A)In the front (anterior)portion of the gill,the amount of oxygen in the gills is lower than the water.
B)Water travels over the gills from anterior to posterior.
C)In the back (posterior)portion of the gill,the amount of carbon dioxide in the gills is higher than the water.
D)Blood flows through the gills from anterior to posterior.

Question 9

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 10

In midsummer,you are fishing at a lake.You catch the most fish at the inlet of a stream into the lake,where logs and branches are creating turbulent flow and mixing deep water with the shallow water near the surface of the lake.What is the probable reason the fish are congregating in this area?

A)This area has higher oxygen content,aiding gill oxygen uptake.
B)This area is warmer,which stimulates metabolism.
C)This area is cooler,which stimulates metabolism.
D)This area has a lower oxygen content,which helps to transfer oxygen into the fish's gills.
E)None of the above apply.

Question 11

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 increase by at least 1 pH unit.
B)The concentration of bicarbonate ions (HCO₃⁻)in the blood would decrease.
C)The medullary respiratory center would increase the rate of breathing.
D)All of the above answers apply.

Question 12

You prop open the gill covers of a fish,tie a string around its tail,and tow it backward through the water.This action forces water to flow in the back of the gill covers,from back to front over the gills,and out through the fish's mouth.What effect would this backward movement have on gas exchange?

A)It would reduce efficiency of gas exchange.
B)It would increase efficiency of gas exchange.
C)The only effect would be the fish's discomfort from this treatment.

Question 13

A mutation results in a form of hemoglobin with binding sites for four molecules of oxygen but does not exhibit cooperative binding.Which of the following would result?

A)Each hemoglobin molecule would bind only one molecule of oxygen.
B)Oxygen would be delivered to the tissues more readily than in a normal individual.
C)The oxygen-hemoglobin dissociation curve would be unaffected.
D)Both A and C would occur.
E)None of the above would result.

Question 14

What is the rate of diffusion in the gas-exchange organ of an air-breathing animal where the area for gas exchange in the lung is 200 mm²,the diffusion constant is 0.08,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 mmHg,and the thickness of the gas exchange membrane is 0.001 mm?

A)800,000
B)125
C)00032
D)10,000,000

Question 15

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 16

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,fresh water at high elevation
D)cool,fresh water at high elevation
E)cool,fresh water at low elevation

Question 17

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 air through lungs or gills
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 18

Why is it more difficult to obtain enough oxygen via respiration from water than from air?

A)The density of water makes ventilating the respiratory tissues more difficult.
B)The viscosity of water is less than that of air.
C)The solubility of oxygen in water is less than in air.
D)All of the above answers apply.
E)Only A and C apply.

Question 19

What is the main difference between respiration in terrestrial insects and in terrestrial vertebrates?

A)Insects rely on the blood in their circulatory system to deliver oxygen from the air to their tissues,whereas terrestrial vertebrates rely on their lungs to deliver oxygen in air to their tissues.
B)Insects rely on their tracheal system to deliver oxygen in air to their tissues,whereas terrestrial vertebrates rely on their lungs to deliver oxygen to their tissues through the blood in their circulatory system.
C)Insects have a lower metabolic rate than terrestrial vertebrates do,so they tend to rely more heavily on their circulatory system than their tracheal system for oxygen transport.
D)Insects use their tracheal system to transfer oxygen from air into blood,whereas terrestrial vertebrates use their lungs to transfer oxygen from air into blood.

Question 20

How does lymph differ between closed and open circulatory systems?

A)In a closed system,lymph is always inside of vessels,whereas,in an open system,lymph can escape.
B)In a closed system,lymph travels through a set of vessels separate from blood,whereas,in an open system,they never separate.
C)In an open system,all the white blood cells are located in lymph only,whereas,in a closed system,they are located in blood only.
D)All of the above answers are true concerning lymph.

Question 21

Which of the following conditions would be the most likely result of an abnormally high blood pressure in an animal,like a reptile,possessing a closed circulatory system?

A)hemorrhage in the capillary beds
B)hemorrhage in the aorta
C)reversal of normal blood flow direction in the veins
D)all of the above

Question 22

Which of the following result,either directly or indirectly,when carbonic anhydrase is functioning properly?

A)The amount of oxygen released by hemoglobin decreases.
B)The amount of carbon dioxide diffusing into red blood cells increases.
C)The pH of capillary blood decreases.
D)Only A and B are true.
E)Only B and C are true.

Question 23

Which of the following mechanisms play a role in regulating heart rate?

A)chemical messengers in the blood,such as epinephrine
B)nerves originating from the medulla (lower part of the brain)
C)pacemaker cells within the heart
D)all of the above (A to
E)only A and C

Question 24

Which of the following mechanisms are used to regulate blood pressure in the closed circulatory system of vertebrates?

A)changing the force of heart contraction
B)constricting and relaxing sphincters in the walls of arterioles
C)adjusting the volume of blood contained in the veins
D)all of the above

Question 25

What effect would increasing lymph heart pressure have?

A)Blood volume would increase.
B)Blood volume would decrease.
C)Hemorrhage would increase.
D)Hemorrhage would decrease.
E)None of the above answers apply.

Question 26

You are a physician,and see 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 27

Blood is pumped at high pressures in arteries from the heart to ensure that all parts of the body receive adequate blood flow.Capillary beds,however,would hemorrhage under direct arterial pressures.How does the design of the circulation network contribute to reducing blood pressure to avoid this scenario?

A)Blood flow through the capillaries is essentially frictionless,and this reduces the amount of pressure on their walls.
B)The total cross-sectional diameter of the arterial circulation increases with progression from artery to arteriole to capillary,leading to a reduced blood pressure.
C)Fluid loss from the arteries is high enough that pressure drops off significantly by the time blood reaches the capillaries.
D)All of the above answers apply.

Question 28

In a cross section through an artery and vein running parallel in your leg,which would be the artery?

A)The vessel with the largest interior diameter.
B)The vessel with more muscle tissue in the wall.
C)The vessel lined with endothelium.
D)The vessel with valves to prevent backflow.
E)All of the above answers apply.

Question 29

Which of the following is the normal sequence of signal conduction in the human heart?

A)neural and chemical messengers → SA node → atria → AV node → ventricles
B)neural but not chemical messengers → AV node → ventricles → SA node → atria
C)chemical but not neural messengers → atria → SA node → ventricles → AV node
D)neural and chemical messengers → ventricles → SA node → atria → AV node
E)neural and chemical messengers →AV node → atria → SA node → ventricles

Question 30

Many organs have adaptations to increase the rate of diffusion of a gas or solute.How are fish gills adapted to optimize oxygen absorption?

A)Bidirectional flow of water across the gills
B)Co-current flow of water across the gills and blood within the gill capillaries
C)Continual flow of water across the gills
D)Countercurrent flow of water across the gills and blood within the gill capillaries

Question 31

Baroreceptors sensing a rapid increase in blood pressure will likely result in

A)reduced cardiac output.
B)increased cardiac output.
C)constricted arterioles and veins.
D)both A and C.
E)both B and C.

Question 32

If atrial natriuretic peptide (ANP)has an effect on the lymph hearts,what effect would logically be predicted?

A)Lymph heart rate would increase.
B)Lymph heart rate would decrease.
C)Lymph heart pressure would increase.
D)Lymph heart pressure would decrease.
E)Either A or C or both.

Question 33

An animal has a cardiac output of 40 mL/min 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 34

Insect trachea come in direct contact with the internal organs to which they deliver oxygen.What parameter of Fick's Law does this optimize?

A)A
B)K
C)P
D)D

Question 35

Baroreceptors are specialized pressure-sensing nerve cells that are important in circulatory homeostasis.Where are these nerve cells located in humans?

A)cells in brain
B)arteries entering the neck region
C)arteries leaving the heart
D)all of the above
E)only B and C

Question 36

Premature infants may not produce surfactants in the alveoli of their lungs.What implications does this have for their health and survival?

A)The partial pressure of oxygen drops significantly in the absence of these surfactants,and the child may suffer brain damage from oxygen deprivation.
B)The surface tension of fluids in the lungs may be too high for the lungs to expand fully during inhalation.
C)Surfactants are necessary to trap pollutants and other material that enters the lungs during inhalation;thus,lung disease is more likely.
D)Surfactants raise the surface tension of alveolar fluids so that deoxygenated air does not get trapped in the lungs during exhalation.

Question 37

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

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

Question 38

Which of the following is the correct sequence of terms describing fluid movement throughout the vessels and tissues of the body,starting with the circulatory system?

A)blood → lymph → blood → interstitial fluid
B)blood → lymph → interstitial fluid → blood
C)blood → interstitial fluid → lymph → blood
D)blood → interstitial fluid → blood → lymph

Question 39

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 40

Which of the following functions is not a function of insect hemolymph?

A)transport of hormones
B)transport of wastes
C)transport of carbon dioxide
D)transport of cells involved in the immune response

Question 41

Figure 44.1
On the ECG above,which waveform represents electrical activity within the atria?

A)1
B)2
C)3

Question 42

Which of the following is a function of the insect tracheal system?

A)transport of hormones
B)transport of wastes
C)transport of carbon dioxide
D)transport of cells involved in the immune response

Question 43

Figure 44.1
On the ECG above,which waveform represents ventricular electrical activity?

A)1
B)2
C)3

Question 44

Figure 44.1
On the ECG above,which waveform represents ventricular relaxation?

A)1
B)2
C)3

Question 45

Figure 44.1
On the ECG above,within which waveform would atrial relaxation occur?

A)1
B)2
C)3

Question 46

Where does the blood within the pulmonary vein travel next?

A)alveolar capillaries
B)left atrium of the heart
C)right atrium of the heart
D)pulmonary artery