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ANIMAL > Measuring Metabolism (W9) > Flashcards

Measuring Metabolism (W9) Flashcards

1
Q

Which metabolism type/eg is the main source of energy & heat?

A

Krebs cycle.

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2
Q

Calorimetry?

A

= the measuring of heat.

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3
Q

Ways of measuring MR/Calorimetry types? (3)

A

• Direct calorimetry.
• Indirect calorimetry.
• Remote calorimetry.

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4
Q

Direct calorimetry?

A

= direct measure of heat produced by the organism.

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5
Q

Indirect calorimetry?

A

= involves the measurement of MR either using respiratory gases or changes in food consumption & excretion.

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6
Q

Remote calorimetry?

A

= the measurement of changes in isotopic markers.

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7
Q

Equipment to measure energy content of food?

A

Adiabatic bomb calorimeter.

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8
Q

Adiabatic?

A

= no heat leaving the system.

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9
Q

Direct calorimetry attributes? (6)

A

• Uses anaerobic & aerobic metabolism.
• Most true measure.
• Laborious & complex.
• Animal is enclosed in a chamber.
• Measures calories/joules of heat produced per unit time.
• Not used anymore.

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10
Q

How is heat produced for metabolism?

A

Through an inactive animal (not doing work) which produces heat.

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11
Q

Results of metabolism? (2)

A

• Production of heat.
• Production of work.

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12
Q

Why is the animal enclosed in a chamber?

A

To ensure that there’s no other heat exchange occurring/present except that from the animal.

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13
Q

Attribute of a stressed animal?

A

High MR.

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14
Q

What is the heat produced?

A

Rise in the temperature measured.

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15
Q

Why should there be an Air in & Air out in the bomb calorimeter?

A

Because the animal requires O2.

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16
Q

Indirect calorimetry attributes? (3)

A

• Uses aerobic metabolism only.
• Measures BMR.
• One can calculate the aerobic scope via BMR.

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17
Q

Indirect calorimetry method types? (2)

A

• Respirometry: O2 consumption/CO2 production.
• Net energy assimilation: Energy ingested/excreted.

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18
Q

Respirometry?

A

= method to measure the MR via O2 consumption & CO2 production.

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19
Q

Respirometry types? (2)

A

• Closed respirometry system.
• Open respirometry system.

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20
Q

How to go about measuring respirometry for aquatic animals? (3)

A

• In water medium.
• Measures change in gas concentration in water over time.
• Enclosed container via titration or with O2 probe.

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21
Q

Enclosed container for aquatic animals modes? (2)

A

• Via titration.
• With O2 probe.

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22
Q

How to go about measuring respirometry for terrestrial animals? (3)

A

• In air medium.
• Closed system: change in volume/pressure = change in gas concentration.
• Open system: inflow vs outflow gas concentrations.

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23
Q

Closed respirometry system is used for which animals?

A

Animals with low MR.

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24
Q

Eg of animals with low MR?

A

Ectotherms.

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25
Q

Open respirometry system is used for which animals?

A

Animals with high MR.

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26
Q

Egs of animals with high MR? (2)

A

• Birds.
• Mammals.

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27
Q

Describe closed system in air for terrestrial animals?

A

Change in volume/pressure = change in gas concentration.

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28
Q

Describe open system in air for terrestrial animals?

A

Inflow vs outflow gas concentrations.

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29
Q

Open respirometry system?

A

= air moves through system.

30
Q

Eg of closed respirometry system?

A

Respirometer from Metabolism practical.

31
Q

Eg of open respirometry system?

A

O2 analyser.

32
Q

RER stands for?

A

Respiratory Exchange Ratio.

33
Q

RER is AKA?

A

Respiratory quotient.

34
Q

RER formula?

A

RER = CO2 produced/ O2 consumed.

35
Q

Respirometry: O2 consumed/CO2 produced attributes? (3)

A

• Meaures only the aerobic component of metabolism.
• Must convert to joules if you want energy expenditure.
• Measured over relatively short periods (hours).

36
Q

What does RER help with?

A

Helps determine proportions of fuel molecules.

37
Q

What does the amount of energy per unit of O2 consumed depends on?

A

Type of fuel molecule metabolized.

38
Q

Energy ingested/excreted attributes? (4)

A

• Measured over long periods (weeks to months).
• Animal is in a semi-natural setting.
• Determines energy content & amounts of food consumed vs faeces produced.
• Apparent Assimilation Efficiency is calculated.

39
Q

(Apparent) Assimilation Efficiency?

A

= the ratio of the amount of food absorbed to the total food ingested by an animal.

40
Q

What does the Assimilation Efficiency equation help with?

A

Gives the total energy assimilated into the body.

41
Q

Assimilation Efficiency equation?

A

AE = (energy content of food × amount of food consumed) – (energy content of faeces × amount of faeces excreted)

42
Q

What to determine regarding the food consumed vs faeces produced? (2)

A

• Determine energy content of each.
• Determine amount of each.

43
Q

Remote calorimetry attributes? (3)

A

• Used to estimate FMR.
• Can’t be used on aquatic or amphibian animals.
• Has 2 different techniques.

44
Q

Uses of isotope markers? (2)

A

• To measure CO2 excretion.
• To measure H2O loss.

45
Q

Forms of Oxygen? (2)

A

• ¹⁶O.
• ¹⁸O.

46
Q

Oxygen forms attribute?

A

Both stable.

47
Q

Forms of Hydrogen? (3)

A

• ¹H.
• ²H.
• ³H.

48
Q

¹H attribute?

A

Stable.

49
Q

²H attributes? (2)

A

= deuterium.
• Stable.

50
Q

³H attributes? (2)

A

= tritium.
• radio-active.

51
Q

Animals used to measure FMR?

A

Free-ranging animals.

52
Q

What do you measure in free-ranging animals?

A

Average MR over a given time.

53
Q

Remote calorimetry techniques? (2)

A

• Tritiated water technique.
• Doubly labelled water technique.

54
Q

Tritiated water technique?

A

= where ³H is the only isotope labelled.

55
Q

Doubly labelled water technique?

A

= where both hydrogen & oxygen atoms (¹⁸O & ²H) are labelled.

56
Q

Tritiated water technique = …?

A

³H only.

57
Q

Doubly labelled water = …? (2)

A

• ¹⁸O.
• ²H.

58
Q

Why stable isotopes?

A
59
Q

What does “Body in isotopic equilibrium” mean?

A

= isotopes are evenly distributed in the body.

60
Q

Most important technique to use?

A

Doubly labelled water technique.

61
Q

Doubly labelled water technique attributes? (4)

A

• Body is in isotopic equilibrium.
• O2 is lost from the body via H2O loss & CO2 excretion.
• H is lost only via H2O loss.
• The difference between the rate of these will be CO2 production.

62
Q

How is O2 lost from the body? (2)

A

• H2O loss.
• CO2 excretion.

63
Q

How is H lost from the body?

A

H2O loss.

64
Q

CO2 + H2O —> HCO-3 + H+ attributes? (3)

A

• Enzyme = Carbonic anhydrase.
• Most CO2 in erythrocytes undergoes this reaction.
• Reversed at lung surface.

65
Q

Doubly labelled water technique method/steps? (5)

A

● Inject animal with ²H2 ¹⁸O water.

● Take initial blood sample.

● Release the animal & recapture it after a period.

● Take second blood sample.

● Determine differences in rates of loss of ²H & ¹⁸O (indicates CO2 produced, thus MR).

66
Q

What to do after injecting animal?

A

Allow time to mix for equilibrium to be reached (~1hr).

67
Q

How long to wait before recapture?

A

Days to weeks.

68
Q

Why wait for days to weeks before recapture?

A

To allow for enough time for energy metabolism.

69
Q

Pros of Doubly labelled water technique method/steps? (2)

A

• It is accurate.
• Minimal disturbance to the animal & in a natural setting.

70
Q

Potential sources of error of Doubly labelled water technique method/steps? (5)

A

● Time interval too short = minimal decline of isotopes.

● Time interval too long = isotope concentration reaches background levels.

● If H2O turnover rates > CO2 production.

● If H2O turnover or CO2 production vary over sample period.

● If ¹⁸O is isolated in other parts of the body.

71
Q

In what animals can H2O turnover rates > CO2 production? (2)

A

• Aquatic animals.
• Amphibians.

72
Q

Limitations/Problems to direct calorimetry?

A

Because you have to measure ALL the heat produced by the animal to measure metabolism, it may be that there are ways that heat can escape as you also have Air in & Air out components.

ANIMAL (21 decks)

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