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Comparative Anatomy And Physiology Of Animals > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Metabolism definition

A

The sum of processes by which animals acquire energy, channel energy into useful functions and dissipate energy from their bodies

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2
Q

Catabolism

A

Break down organic molecules to release energy at the cellular level

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3
Q

Anabolism

A

Use energy to create organic molecules at the cellular levek

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4
Q

Obligate heterotrophs

A

Consumer other organisms to survive

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5
Q

Physiological work

A

Any process carried by an animal that increases order eg
Synthesis of macromolecules
Generating electrical gradients by actively transporting solutes across a membrane
Muscle contraction to move a limb

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6
Q

Temperature

A

A measure of the intensity of random atomic -molecular motions

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7
Q

Heat (molecular kinetic energy) and physiological work

A

Animals cannot use heat energy to form any type of physiological work and it is usually a waste product of physiological work.

system can only convert heat to work if there is a temperature difference between the two parts of the system

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8
Q

High grade energy

A

Capable of doing physiological work- chemical, electrical or mechanical energy

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9
Q

Low grade energy

A

Cannot do physiological work- heat

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10
Q

Efficiency of energy transformation

A

Output/input
Always less than 100% as energy lost as heat

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11
Q

Efficiency of glucose to muscular motion

A

Glucose → ATP is 70% efficient
ATP → Muscular motion is 30% efficient
Therefore Glucose → Muscular motion is 21% efficient

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12
Q

Biosynthesis

A

ingested chemical energy that is absorbed is used to produce organic molecules each with a significant energy content
Some molecules are assembled into new tissues during growth
Some molecules are lost – gametes, milk, mucus, sloughed skin, hair are lost from the body
Biosynthesis produces heat…

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13
Q

Maintenance

A

ingested chemical energy that is absorbed is used to maintain the integrity of the animal’s body
This chemical energy is invariably degraded to heat during maintenance
Internal mechanical work – blood being pumped produces heat through friction or gut motility

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14
Q

Generation of external work

A

ingested chemical energy that is absorbed is used to apply mechanical forces to objects outside the body
Whilst mechanical work generates heat some is transmitted to the environment
Energy of external work can be stored if it is converted into increased potential energy of position

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15
Q

3 major types of physiological work

A

Biosynthesis
Maintenance
Generation of external work

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16
Q

Poikilothermic and moist skin

A

Eg frog

Rates of heat production are low
Have poor insulation
Heat produced is easily dissipated to the environment

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17
Q

Homeothermic

A

Eg bird

Rates of heat production are high
Have good insulation
Heat produced is retained within the body

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18
Q

Conversion of chemical-bond energy to heat

A

Irreversible
Energy is not recycled

Animals continually convert ingested chemical energy (food) into heat
Photon energy from the sun is harnessed by photosynthesis to produce chemical-bond energy
Organisms convert this ultimately to heat which radiates to outer space

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19
Q

Metabolic rate

A

The rate at which chemical energy is converted to heat and external work (mainly heat)

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20
Q

Measure of heat production

A

Joules per unit time (watts)

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21
Q

Why is metabolic rate important

A

Determinant of how much food an animal needs
Heat production provides a quantitative measurement of the total activity of all physiological mechanisms
Metabolic rate measures the drain that an animal places on the physiological useful energy supplies of its ecosystem

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22
Q

Direct calorimetry

A

measures the rate at which heat leaves the animal’s body – direct measure of metabolic rate
e.g. Lavoisier’s direct calorimeter

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23
Q

Indirect calorimetry

A

1) measures the rate of respiratory gas exchange (respirometry)
or
2) measurement of the chemical energy balance of an animal by measuring food consumed and excreted (material-balance method

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24
Q

Respirometry

A

determines the oxygen consumption of a bird embryo
mlO2 per hour = respiration rate which can be converted to heat production if metabolic substrate is known

If animal is consuming 10 mL O2 per hour and substrate is glucose then heat produced would be 211 J per hour
However, conversion depends on the foodstuff being metabolised

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25
Q

Measuring metabolic rate in animals

A

Direct or indirect calorimetry

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26
Q

Respiratory quotient

A

Moles of CO2 per unit time/ moles of O2 per unit time

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27
Q

RQ of carbohydrate

A

1.0

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28
Q

RQ of lipids

A

0.71

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29
Q

RQ of proteins

A

0.83

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30
Q

Material-balance method

A

Measure the chemical energy content of the food consumed by an animal over time
Measure the chemical energy of the faeces and urine over the same time period (at least 24 hours)
Difference gives an estimate of metabolic rate in Watts
Problems arise if animal is increasing (growth) or decreasing body mass (shedding skin)

determined by burning the molecules to destruction and measuring the rise in temperature in a bomb calorimeter

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31
Q

Factors affecting metabolism in animals - large effects

A

Physical activity - ↑ with increasing activity
Environmental temperature
-Homeothermic species – lowest in thermoneutral zone# & ↑ for both above and below thermoneutral zone
-Poikilothermic species - ↑ with increasing temperature and ↓ with decreasing temperature

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32
Q

Thermoneutral zone

A

Ambient temperature that does not impact body temperature

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33
Q

Factors affecting metabolism- small effects

A

Ingestion of meal - ↑ for several hours after ingestion (specific dynamic action [SDA])
Body size – mass-specific ↑ as size ↓
Gender - ↑ in male humans
Hormonal status - ↑ with thyroid secretions
Time of day - ↑ during daytime
Age – mass-specific rate ↑ during puberty then ↓
Environmental O2 – Often ↓ as O2 ↓ below threshold
Salinity of water – osmoregulating crabs ↑ in diluted sea water

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34
Q

Basal metabolic rate

A

applies to homeotherms
Thermoneutral zone
Fasting (i.e. long time after meal that would have raised the metabolic rate)
Resting (inactive but awake)

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35
Q

Standard metabolic rate

A

applies to poikilotherms
Fasting (i.e. long time after meal that would have raised the metabolic rate)
Resting (inactive)

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36
Q

Size and metabolism

A

Per gram of body mass, small animals have a higher metabolic rate than large animals

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37
Q

Metabolic scaling

A

exhibits negative allometry
M = aWb
As body mass increases then metabolic rate increases at a slower rate, i.e. b < 1.0

38
Q

Mass-specific metabolic rate

A

M/W = aW(b-1)

As body mass increases then mass-specific metabolic rate increases at a slower rate

39
Q

Active metabolic rate

A

also typically an allometric function of body mass
The metabolism – body mass relationship pervades all aspects of animal physiology
Heart mass (and lung mass ) scales isometrically with body mass, i.e. b = ~1.0

40
Q

Heart rate in animals

A

Heart rate is lower in bigger animals and lower in more long lived animals.

Note that humans have a longevity value that is longer than expected based on body mass, which reflects their ability to alter their environment and use medicine to stave off diseases and conditions that shorten life.

41
Q

Metabolism and ecosystems

A

Population body mass of mammal species on an African savannah (per km²) scales with body mass of the species

42
Q

Metabolism and toxicity

A

Body size affects how animals metabolise chemicals – higher metabolic rate in small mammals leads to a higher concentration of toxins but can catabolise these chemicals faster.
Leads to higher dose per unit mass for veterinary drugs in smaller mammals

43
Q

Rubner’s surface law

A

BMR of a mammal was proportional to its body surface area which scales to volume at 0.667
Not seen as being universally applicable – b ≠ 0.667 and patterns apply to non-mammals and mammals aike
In reality b ≠ 0.667 for all taxa…..
Modern view is that rates of transport, i.e. blood supplies, may be geometrically constrained in distinctive ways as body mass scales up or down

44
Q

With respect to Figure 1, which one of the following statements is correct?

A - Absorbed chemical energy can be used to generate external work
B - All chemical energy absorbed is kept within the body
C - All ingested energy is absorbed
D - Biosynthesis does not generate heat
E - Growth is the result of maintenance activities

A

A

45
Q

What is metabolism related to

A

Energy absorbed not energy ingested

46
Q

What is the by-product of any metabolic process?

A

Heat

47
Q

Is resting heart rate high or low for a mammal weighing over 10 kg?

A

Low

48
Q

What kind of energy is created by the separation of positive and negative charges?

A

Electrical energy

49
Q

Why are frogs cold to the touch?

A

poikilothermic and moist skin
Rates of heat production are low
Have poor insulation
Heat produced is easily dissipated to the environment

50
Q

What is defined by lower and upper critical temperatures?

A

Thermoneutral zone

51
Q

What does rate of oxygen uptake depend on

A

Volume of flow of air or water per unit time
Amount of O2 removed from each unit of volume

52
Q

Rate of O2 uptake

A

Rate of O2 uptake (mL O2 / min) = Vmedium(CI – CE)
Vmedium = rate of flow of the medium (L/min)
CI = O2 concentration of inhaled medium (mL O2 / L medium)
CE = O2 concentration of exhaled medium (mL O2 / L medium)

53
Q

Number of haem groups per 100 ml of human blood

A

5.4 x 10^20

54
Q

4 respiratory pigments

A

Haemoglobin
Haemocyanin
Chlorocruorins
Haemerythrins

55
Q

Haemoglobin

A

contain heme and are based around iron (widespread in many taxa)

56
Q

Haemocyanin

A

contain copper bound to the proteins (two orders)

57
Q

Chlorocruorins

A

iron-based, dissolved in fluids (four families of annelid worm)

58
Q

Haemerythrins

A

iron-based extracellular proteins in four invertebrate phyla

59
Q

Erythrocytes

A

Vary in size and shape in vertebrates
All species except for mammals have nucleated red blood cells
All contain haemoglobin
Produced in bone marrow under hormonal control (erythropoietin produced in kidneys)

60
Q

Oxygen-haemoglobin equilibrium curve

A

One haem group can only bind one O2 molecule at a time so each haemoglobin molecule complex can bind 4 molecules of oxygen. However, the oxygen saturation of the blood is a function of the partial pressure (Po2) of the blood but it is not a straight line but rather is sigmoidal (S-shaped). Uptake by haemoglobins is relatively slow but at partial pressures between 20 and 60 mm Hg the uptake of oxygen, expressed as percentage of all possible binding sites, accelerates before slowing again. This means that at oxygen concentrations in the blood that are high the oxygen tends to stay bound to the haemoglobin, but as the oxygen is used by tissues and the partial pressure drops then the oxygen can be rapidly released as it is needed.

61
Q

Venous reserve

A

pO2 of blood leaving a particular tissue

62
Q

Venous reserve

A

pO2 of blood leaving a particular tissue

63
Q

What is venous reserve dependent on

A

Rate of blood flow through the tissue
Arterial pO2
Amount of haemoglobin per unit of blood volume
Tissue’s rate of oxygen consumption

64
Q

What type of animalia has a uncleared red blood cells

A

Mammals

65
Q

How do oxygen equilibrium curves vary

A

1) in shape because of the various molecular forms of haemoglobin in different species
2) in height which reflects the amount of haemoglobin present in the blood

66
Q

P50

A

P50 is an index of the affinity of a respiratory pigment to O2
P50 is the partial pressure in the blood at 50% oxygen saturation

67
Q

Bohr effect

A

A decrease in pH (more acid) reduces oxygen affinity and shifts oxygen equilibration curve to the right

An increase in CO2 reduces oxygen affinity and shifts oxygen equilibration curve to the right

68
Q

Temperature and oxygen affinity

A

An increase in temperature decreases oxygen affinity and shifts oxygen equilibration curve to the right

Blood at high temperature can carry more oxygen at saturation

69
Q

The root effect (teleost fish)

A

A decrease in pH (more acid) reduces the oxygen-carrying capacity of haemoglobin in eels

70
Q

CO2 transport

A

Carbon dioxide dissolves in blood plasma as CO2 molecules
Only a small fraction is as a dissolved gas
When CO2 dissolves in an aqueous solution it forms carbonic acid (H2CO3) which then dissociates into a hydrogen ion and a bicarbonate ion
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-
Bicarbonate ions can also dissociate into hydrogen ion and a carbonate ion but this is rare in most animals
HCO3- ↔ H+ + CO32-
CO2 in dissolved form acts as an acid (produces H+)

Bicarbonate ions rarely form if CO2 in dissolved in distilled water or a salt (NaCl) solution controlled by gas solubility
Bicarbonate dominates in blood of animals because of molecules that buffer pH, i.e. then they can control the numbers of H+ in the blood
[H+ ][HCO3-] = Kco2
[CO2]
The concentration of bicarbonate is inversely related to the concentration of H+
Blood buffers “soak” up H+ so HCO3- levels are high

71
Q

Buffers

A

HX ↔ H+ + X-
Add H+ then more buffer (X) is recruited and more HX is formed removing the excess H+
Remove H+ then HX dissociates to form buffer (X) and more H+
HX and X- are a buffer pair
[H+ ][X-] = Kx
[HX]
Kx is a constant for that particular buffer reaction under prevailing conditions, particularly temperature
Greatest buffering effectiveness when [H+ ] = [X-]

72
Q

2 key blood buffer groups

A

Terminal amino group of protein chains
Imidazole where amino acid histamine occurs in a protein molecule

73
Q

Predominant buffering groups

A

Imidazole

74
Q

How is carbon dioxide transported in blood

A

1) as dissolved gas (CO2 )
2) as bicarbonate ions (HCO3-)
3) as carbamate (carbamino) group (-NH-COO-), i.e. chemically combined on amino acids of haemoglobin or other blood proteins
In humans 90% is as bicarbonate ions

75
Q

Carbon dioxide curve

A

Shape of curve is determined by kinetics of bicarbonate formation in the blood and hence types and efficiencies of blood buffer groups

The carbon dioxide equilibrium curve tend to be a simple curve determined by the production and maintenance of bicarbonate ions.

76
Q

Haldane effect

A

Deoxygenation promotes CO2 uptake (in tissues)
Oxygenation promotes CO2 release (in lungs)

77
Q

CO2 transport in vertebrate blood

A

CO2 + H2O ↔ H+ + HCO3- is naturally slow = bottleneck in blood’s ability to take up, transport and release CO2
Carbonic anhydrase speeds up this reaction (only one in process that is catalysed)
Carbonic anhydrase is found within red blood cells but not free in the plasma
Sometimes found in epithelial walls of capillaries

78
Q

pH of human blood

A

Humans - 37°C – pH of 7.4
Near death if pH = 7.7 or 6.8

79
Q

Acid-base physiology - short term response

A

If a person’s blood becomes too acidic (↑ H+) hyperventilation will lower dissolved CO2 in the blood
CO2 ↓ + H2O ↔ H2CO3 ↔ H+ ↓ + HCO3-
Lowering concentrations of CO2 in the blood reduces the number of H+ and so lowers pH

If a person’s blood becomes too alkaline (↓ H+) reduced ventilation will increase dissolved CO2 in the blood
CO2 ↑ + H2O ↔ H2CO3 ↔ H+ ↑ + HCO3-
Elevating concentrations of CO2 in the blood increases the number of H+ and so increases pH

80
Q

Where does the conservation of bicarbonate ions occur

A

Terrestrial species - kidney
Aquatic species - gill epithelium

81
Q

Where does the conservation of bicarbonate ions occur

A

Terrestrial species - kidney
Aquatic species - gill epithelium

82
Q

Acid-based physiology - long term response

A

If a person’s blood retains bicarbonate (↑ HCO3-) there will be an increase in dissolved CO2 in the blood
CO2 ↑ + H2O ↔ H2CO3 ↔ H+ ↓ + HCO3-
Elevating concentrations of HCO3- in the blood decreases the number of H+ and so increases alkalinity

If a person’s blood loses bicarbonate (↓ HCO3-) there will be an decrease in dissolved CO2 in the blood
CO2 ↓ + H2O ↔ H2CO3 ↔ H+ ↑ + HCO3-
Elevating concentrations of HCO3- in the blood increases the number of H+ and so increases acidity

83
Q

Respiratory disturbances

A

Based around pCO2 in the blood
Panting causes respiratory alkalosis – there is excessive loss of CO2 from the blood - pCO2 drops
Holding your breath causes respiratory acidosis – there is excessive accumulation of CO2 from the blood - pCO2 goes up

84
Q

Metabolic disturbances

A

Based around bicarbonate ions
Chronic diarrhoea leads to excessive loss of HCO3- across the gut lining – causes metabolic acidosis
Lactic acid build-up during exercise adds excessive H+ – causes metabolic acidosis

85
Q

Protein buffers

A

Proteins are made up of amino acids, which contain positively charged amino groups and negatively charged carboxyl groups, which can bind hydrogen and hydroxyl ions
Buffering by proteins accounts for two-thirds of the buffering power of the blood and most of the buffering within cells
Phosphates are found in the blood in two forms: sodium dihydrogen phosphate (Na2H2PO4−) which is a weak acid, and sodium monohydrogen phosphate (NaHPO42-), which is a weak base
Na+ + NaH2PO4− ↔ H+ + Na2HPO42-

86
Q

Ecological effects of acid-base physiology

A

Increases in atmospheric CO2 lead to acidification of water bodies, which are poorly buffered
Increased pH erodes calcified structures to produce carbonate ions
Leads to increase the levels of HCO3- in the water and impact on acid-base regulation by aquatic species

87
Q

How many oxygen atoms can a molecule of mammalian haemoglobin bind?

A

8

88
Q

Why is a counter current flow system more efficient?

A

Equilibrium is not reached
A gas exchange gradient is maintained along the whole length of the system

89
Q

For the Bohr effect, is the following statement true? A decrease in pH (more acid) reduces oxygen affinity and shifts oxygen equilibration curve to the left.

A

False
Curve will shift to the right

90
Q

Which has the larger red blood cells – elephant or hummingbird?

A

Hummingbird

91
Q

What is the chemical formula for carbonic acid?

A

H2CO3

Comparative Anatomy And Physiology Of Animals (8 decks)

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