Deck 26: Oxygen, Carbon Dioxide, and Internal Transport at Work: Diving by Marine Mammals

Question 1

Why do Weddell seals make great study animals for investigating diving physiology?

A) They are diving mammals
B) They are amazingly tolerant of human interventions
C) They dive very deep
D) They are found all over the world

Answer 1

B

Question 2

A seal diving to a depth of 300 m would experience a water pressure of approximately _______ at that depth.

A) 3 atm
B) 13 atm
C) 30 atm
D) 300 atm

Answer 2

C

Question 3

Most dives by Weddell seals are

A) short and shallow.
B) long and shallow.
C) very evenly distributed between short and shallow and long and deep dives.
D) long and deep.

Answer 3

A

Question 4

Refer to the figure shown.
The figure best represents which behavior?

A) Diving behavior of male and female northern elephant seals
B) Foraging behavior of male and female sperm whales
C) Migration movements of male and female northern elephant seals
D) Foraging movements of bottlenose dolphins

Question 5

Which animal is typically the shallowest diver?

A) Elephant seal
B) Cuvier's beaked whale
C) Weddell seal
D) Northern fur seal

Question 6

Which animal does not belong to the true (phocid) seal group?

A) Northern fur seal
B) Weddell seal
C) Ribbon seal
D) Harbor seal

Question 7

Refer to the figure shown.
Which of the following is shown by the data in the figure?

A) Individual dive depths from one seal over many days
B) Dive depths for many seals of one species over many days
C) Dive depths for one seal during one day
D) Dive depths for many seals of one species during one day

Question 8

Refer to the figure shown.
The data in the figure would not likely apply to which species?

A) Northern fur seal
B) Ribbon seal
C) Elephant seal
D) Harbor seal

Question 9

If you were collecting diving data, which comparison would you expect to reveal the greatest physiological differences?

A) A voluntary versus a forced dive
B) A morning versus an evening dive
C) A foraging-related versus a defense-related dive
D) A short versus a long dive (relative to the maximum duration for the species)

Question 10

Which one of the following is not a major internal O₂ store during long dives?

A) O₂ bound to hemoglobin
B) O₂ bound to myoglobin
C) O₂ dissolved in body fluids other than lungs
D) O₂ contained in the lungs

Question 11

Which statement describes an early piece of evidence showing that circulatory function is sometimes radically altered during a dive?

A) A significant bradycardia occurs during a forced dive.
B) A significant bradycardia occurs during a voluntary dive.
C) Lactic acid increases primarily after a forced dive.
D) Lactic acid increases primarily after a voluntary dive.

Question 12

Which statement regarding the diving reflex is true?

A) It is absent during a forced dive.
B) It represents an adjustment to the pattern of blood flow that allows the dive to be extended.
C) It exists in all diving mammals.
D) It is strongly present during a voluntary dive.

Question 13

The amount of O₂ stored in blood depends on the

A) oxygen-carrying capacity of the blood.
B) total volume of the blood.
C) circulatory rate.
D) oxygen-carrying capacity and the total volume of the blood.

Question 14

Seals such as the Weddell seal, which are capable of long and deep dives, typically have blood-oxygen carrying capacities (per unit volume) that are _______ those of seals such as the stellar sea lion, whose dives are short and shallow.

A) four times greater than
B) 1.5 times greater than
C) similar to
D) 1.5 times less than

Question 15

In general, diving mammals have lung volumes (per unit mass) that are _______ those of terrestrial mammals.

A) 4 times greater than
B) 2 times greater than
C) similar to
D) 2 times less than

Question 16

Which oxygen storage compartment tends to be the smallest in diving mammals?

A) Lungs
B) Blood
C) Myoglobin
D) Interstitial fluids

Question 17

Refer to the figure shown.
What data is represented in the figure?

A) Oxygen-carrying capacity
B) Total oxygen stores
C) Mass-specific oxygen stores
D) Mass-specific metabolic rates

Question 18

Refer to the figure shown.
Which data in the figure represents the lungs?

A) I
B) II
C) III
D) IV

Question 19

Refer to the figure shown.
Of the components shown in the figure, the one with the greatest effect on dive length in true (phocid) seals is

A) the lungs.
B) the blood.
C) myoglobin.
D) dissolved O₂ in fluids other than blood.

Question 20

Mass-specific myoglobin levels in the most accomplished divers such as the Weddell seal are _______ those of humans.

A) 10 times greater than
B) 2 times greater than
C) similar to
D) 2 times less than

Question 21

The O₂ partial pressure in the skeletal muscle must be _______ for the muscle's myoglobin to unload O₂ to the mitochondria.

A) high
B) low
C) constant
D) zero

Question 22

A large O₂ store in the lungs is an advantage to a diver for which reason?

A) Large amounts of air in the lungs affect buoyancy.
B) Alveoli are typically the first components of the respiratory system to collapse.
C) A large store of O₂ also means a large store of N₂.
D) In compression-resistant thoraxes, it increases shallow dive time.

Question 23

During a landmark study by Bron (1966), regional vasoconstriction during a seal's dive was indicated by a measured lack of blood flow to the

A) kidneys.
B) brain.
C) lungs.
D) skeletal muscle.

Question 24

Which structure receives little or no blood during a prolonged forced dive?

A) Brain
B) Limbs
C) Lungs
D) Heart

Question 25

A decrease in heart rate specifically in response to diving is referred to as

A) chronic tachycardia.
B) sinus bradycardia.
C) diving bradycardia.
D) diving tachycardia.

Question 26

During a prolonged forced dive, vasoconstriction causes which cardiovascular parameter(s) to drop?

A) Heart rate
B) Stroke volume
C) Cardiac output
D) Heart rate and cardiac output

Question 27

During a prolonged forced dive, vasoconstriction allows which cardiovascular parameter(s) to remain unchanged?

A) Stroke volume
B) Blood pressure
C) Overall resistance to blood flow
D) Stroke volume and blood pressure

Question 28

Refer to the figure shown.
Which statement is supported by the data in the figure?

A) In freely diving seals, diving heart rate varies with dive duration in a graded manner.
B) In freely diving seals, the degree of bradycardia is proportional to dive duration.
C) In forcibly submerged seals, the degree of bradycardia is proportional to dive duration.
D) In forcibly submerged seals, the degree of bradycardia is inversely proportional to dive duration.

Question 29

Refer to the figure shown.
Which value was most likely the resting pre-dive heart rate for the animals represented in figure?

A) 60 beats/min
B) 50 beats/min
C) 10 beats/min
D) The answer is not shown on the y axis scale.

Question 30

Refer to the figure shown.
The data in the figure represent _______ in fish removed from water.

A) ventilation rates
B) heart rates
C) metabolic rates
D) oxygen consumption

Question 31

Refer to the figure shown.
Suppose that the same parameter represented in the figure is measured in aquatic animals that are moved from water to air and terrestrial animals that are moved from air to water. In which animal would the change in the measured parameter be the smallest?

A) Weddell seal
B) Fish that regularly emerge into the air briefly, such as grunion and flying fish
C) Teleost fish
D) Humans

Question 32

Refer to the figure shown.
Measurements of which body component(s) are shown in the figure?

A) Blood
B) Muscle
C) Brain
D) Blood and muscle

Question 33

Refer to the figure shown.
Which statement regarding the data presented in the figure is true?

A) Blood circulation to muscle was significantly increased during the dives.
B) Oxygen supplies for the brain and myocardium remained low during the dives.
C) Muscles switch to anaerobic metabolism at some point during the dives.
D) Circulating blood oxygen continued to be made available from oxygen in muscle.

Question 34

Refer to the figure shown.
What would be the best label for the x-axis in the graph?

A) Length of dive
B) Time after animal resurfaces
C) Duration of anaerobic tolerance
D) Time

Question 35

Refer to the figure shown.
Which statement regarding the data presented in the figure is the most accurate?

A) Blood concentration of lactic acid rises following a dive.
B) During a dive, lactic acid in the muscles increases dramatically.
C) During a dive, lactic acid is metabolized and eventually reaches undetectable levels.
D) Blood lactic acid and muscle lactic acid concentrations are typically mismatched during and after dives.

Question 36

Metabolic limits on dive duration depend on which factor(s)?

A) O₂ supplies
B) O₂ supplies and O₂ consumption
C) O₂ consumption and tissue tolerance to lactic acid
D) O₂ supplies, O₂ consumption, and tissue tolerance to lactic acid

Question 37

Refer to the figure shown.
The data in the figure show that compared to nondiving mammals, diving mammals have

A) hearts that function more efficiently.
B) brains that tolerate hypoxia better.
C) muscles that remain active in the absence of oxygen longer.
D) a more functional nervous system.

Question 38

The metabolic rate in freely diving free-ranging Weddell seals is _______ the metabolic rate of resting nondiving seals.

A) greater than
B) lower than
C) lower than or equal to
D) greater than or equal to

Question 39

What is the primary stimulus for ventilation in diving mammals?

A) Low blood O₂
B) High blood CO₂
C) Low blood pH
D) High blood CO₂ and low blood pH

Question 40

Diving species exhibit _______ to _______ compared to terrestrial species. This delays their urge to inhale.

A) increased sensitivity; blood CO₂ and H⁺
B) increased sensitivity; blood O₂
C) blunted sensitivity; blood CO₂ and H⁺
D) blunted sensitivity; blood O₂

Question 41

Following an extended dive, diving mammals require

A) a significant amount of time to fully metabolize the lactic acid.
B) access to air at the water's surface and a significant amount of time to fully metabolize the lactic acid.
C) an immediate shallow dive to metabolize accumulated lactic acid.
D) access to land in order to metabolize accumulated lactic acid.

Question 42

In the landmark 1980 study by Kooyman et al. on production of lactic acid during diving, blood was collected from seals

A) via an implanted catheter during voluntary dives in the lab.
B) via an implanted catheter during free diving in the wild.
C) following free diving in the wild.
D) following voluntary dives in the lab.

Question 43

The aerobic dive limit (ADL) is the _______ dive that can be undertaken without a(n) _______.

A) longest; net accumulation of lactic acid above resting level.
B) longest; accumulation of lactic acid.
C) deepest; accumulation of lactic acid.
D) longest; alteration of metabolic rate.

Question 44

According to a central hypothesis of diving physiology, it is adaptive for diving mammals to keep their dives shorter than their species-specific aerobic dive limit (ADL) because doing so maximizes _______ and minimizes _______.

A) time spent underwater; the time available for foraging
B) recovery time at the surface; the time spent underwater
C) the time available for foraging; exposure to predation
D) exposure to predation; the time available for foraging

Question 45

In diving mammals, more than _______% of dives are _______ than the ADL.

A) 90; shorter
B) 75; shorter
C) 75; longer
D) 90; longer

Question 46

Diving mammals cannot reduce their metabolic rates while underwater by

A) allowing their tissue to cool.
B) postponing the digestion of food while diving.
C) developing a tolerance for lactic acid.
D) gliding instead of swimming continuously.

Question 47

Weddell seals employ which behavior(s) in order to reduce metabolic costs during a dive?

A) Gliding alone
B) Alternation of stroking and gliding
C) Continuous stroking
D) Gliding and alternation of stroking and gliding

Question 48

Decompression sickness occurs

A) in scuba divers who dive very deep.
B) when N₂ is absorbed from a high-pressure source.
C) when N₂ comes out of solution in the blood.
D) when N₂ is absent in the plasma.

Question 49

Decompression sickness may result in

A) bubbles of gas forming in the blood.
B) joint pain.
C) bubbles of gas forming in the blood and joint pain.
D) bubbles of gas forming in the blood, joint pain, and paralysis.

Question 50

Decompression sickness in divers using scuba tanks _______. Decompression sickness in breath-hold divers _______.

A) can occur during sudden ascents; can also occur during sudden ascents
B) can occur during sudden ascents; is incredibly rare, even during sudden ascents
C) is incredibly rare, even during sudden ascents; can occur during sudden ascents
D) is incredibly rare, even during sudden ascents; is also incredibly rare, even during sudden ascents

Question 51

Diving mammals avoid decompression sickness

A) through increased solubility of N₂ in blood plasma.
B) via alveolar collapse.
C) by binding excess N₂ to hemoglobin.
D) by sequestering excess N₂ in the spleen.

Question 52

Which are advantages of alveolar compression during a deep dive?
I) Prevention of N₂ transfer into blood
II) Reserve of O₂ for use on ascent
III) Prevention of CO₂ transfer to lungs

A) II
B) I and II
C) II and III
D) I, II, and III

Question 53

Why might it be important to retain O₂ in the lungs during a deep dive?

A) To prevent alveolar collapse.
B) To prevent O₂ from diffusing into blood from lungs.
C) To prevent O₂ from diffusing from blood into lungs.
D) To enhance recovery upon ascent.

Question 54

Discuss how technology has advanced our knowledge of marine mammal diving behavior. Provide an example.

Question 55

In any given diving study, what are three important variables that one must know before interpreting the data?

Question 56

How was the original information on the diving reflex updated in studies performed after the 1970s?

Question 57

What are the main O₂ stores used during a dive? Are they similar across marine mammal species?

Question 58

How does vasoconstriction prolong a dive?

Question 59

Is there a relationship between dive duration and bradycardia? If so, does it depend on the type of dive performed?

Question 60

What are the factors that determine dive duration? Place them in order of significance.

Question 61

Discuss the aerobic dive limit (ADL) and the adaptive significance of keeping dives under this limit.

Question 62

What is decompression sickness and how do marine mammals avoid it?

Question 63

Discuss advantages and disadvantages of sequestering O₂ in the lungs during a deep dive.