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BIO 203 > Module 1: Heat Transfer + Thermoreg. > Flashcards

Module 1: Heat Transfer + Thermoreg. Flashcards

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1
Q

Heat

A

Kinetic energy embedded in molecules (molecular motion)

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2
Q

Temperature

A

An index of molecule motion (the average kinetic energy)

–> Hot = High KE
–> Cold = Low KE

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3
Q

Heat Transfer

A

The movement of heat energy from one place/material to another

–> Occurs wherever there is a temperature difference

–> Has 4 main methods

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4
Q

Methods of Heat Transfer (4)

A

1) Conduction
2) Convection
3) Radiation
4) Evaporation

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5
Q

Conduction

A

Heat transfer through STATIONARY matter by PHYSICAL CONTACT

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6
Q

Driving Force of Conduction

A

Temperature gradient (difference in temp between the two objects)

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7
Q

T1 > T2

A

Heat flows from T1 to T2

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8
Q

T1 < T2

A

Heat flows from T2 to T1

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9
Q

T1 = T2

A

No NET transfer; heat is still transferring between the two but it is just occurring at an equal rate in opposite directions

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10
Q

Heat always flows from…

A

High temp (heat content) to Low temp (heat content)

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11
Q

Rate of Heat Transfer Equation

(and simplified form)

A

dQ/dt = [(K*A)/ L] * [T2 - T1]

Flow = Ease of Movement * Driving Force

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12
Q

Ease of Movement

A

The physical constraints to flow of substances (Determined by physical characteristics)

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13
Q

Ease of Movement (part of the equation)

A

(K*A) / L

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14
Q

What is “K” in the heat flow equation?

A

K = Thermal Conductivity (of the material)

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15
Q

What is “A” in the heat flow equation?

A

A = Surface area of contact

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16
Q

What is “L” in the heat flow equation?

A

L = Length/distance between objects

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17
Q

Convection

A

The transfer of heat from one place to another due to the movement of fluid/air

A modified form of conduction in which one or more of the units can move relative to each other

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18
Q

Two main types of convection:

A

1) Forced Convection
2) Free Convection (AKA “Natural”)

–> Differentiated by how the movement of the object/s is initiated

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19
Q

Free Convection

A

Environmental medium movement is caused by natural means
(passive movement)

(Ex: Hot air rising)

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20
Q

Forced Convection

A

Environmental medium movement is externally/physically induced

(Ex: Fan moving the air)

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21
Q

Heat flow of free and forced convection differ mainly in their…

A

DRIVING FORCE (temp. gradient)

Free Convection: Much less heat transfer due to the formation of boundary layers

Forced Convection: Much more heat transfer due to the disruption of the formation of boundary layers

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22
Q

Effect of boundary layers on convection

A

Boundary layers decrease the TEMP GRADIENT between two mediums

Ex: Air around the body DOES NOT = the environmental temp as the air directly around the skin has a slightly higher temp due to heat loss from our bodies going into the air (warming it up)

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23
Q

Radiation

A

Electromagnetic Waves

–> All objects both ABSORB and EMIT electromagnetic waves

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24
Q

Heat Loss from Radiation

A

If an object has KE, some of that energy will radiate away from the object

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25
Q

Heat Gain from Radiation

A

If electroneg. radiation coming down as thermal energy hits a surface, it can absorb (gain) that energy

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26
Q

Evaporation

A

The transformation (of water) from liquid to gas

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27
Q

Heat of Vaporization

A

Evaporation requires energy (heat of vaporization)

–> Will pull heat from whatever the substance is on to transfer from liquid to gas, “taking the heat with it”

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28
Q

Evaporative Cooling

A

As water moves from liquid to gas, it absorbs heat from the body and carries it away in its gaseous form = HEAT LOSS

–> Evaporation only leads to HEAT LOSS; never heat gain

29
Q

Thermal Budget

A

A concept referring to the balance between heat gain and loss overtime to maintain a relatively constant body temperature

Heat gain = Heat loss

30
Q

Heat gain mechanisms

A

**External Exchange: **
1) Conduction
2) Convection
3) Radiation

**Internal: **
4) Metabolic Rate (endogenous heat production)

31
Q

Heat loss mechanisms

A

External Exchange:
1) Conduction
2) Convection
3) Radiation
4) Evaporation

Internal:
N/A

32
Q

Thermoregulation

A

The maintenance of physiological core body temperature by balancing heat generation with heat loss

33
Q

Why must body temperature be regulated?

A

So that rxns. occur at a sufficient rate

34
Q

If body temperature is too high…

A

Enzymes needed for rxns. denature and biochemical pathways fail = Death

35
Q

If body temperature is too low…

A

Enzyme activity slows/stops due to insufficient KE to cause enzyme-substrate collisions

36
Q

Maintaining body temp at a specifific optimal temp allows…

A

For enzymes to function at a rate efficient enough to meet cellular demands without having a temp that is too high/low that stops/slows enzymatic activity

37
Q

Reaction Rate and Temperature Relationship

A

Reaction rate increases exponentially with temperature increase

38
Q

3 main strategies for thermoregulation:

A

1) Ectothermy
2) Endothermy
3) Heterothermy

39
Q

Ectothermy

A

Use of external heat to thermoregulate; body temp varies WITH environmental temp

AKA “Poikilotherms”, “Cold Blooded”, “Variable Tb”

40
Q

Organisms that are Ectotherms

A

1) Reptiles
2) Amphibians
3) All non-vertebrate species (insects/crustaceans)
4) Fish + sharks

41
Q

In ectotherms, body temp is ____________ to environmental temp

A

PROPORTIONAL

Tb = Tamb

42
Q

Ectotherms: Metabolic rate and environmental temp relationship

A

MR varies with Tamb

43
Q

Ectotherms: High environmental temp

A

= High MR, animal is faster, > need for energy

44
Q

Ectotherms: Low environmental temp

A

= Low MR, animal is sluggish, < need for energy

45
Q

Advantages of Ectothermy (3)

A

1) Requires less energy
–> Don’t need to increase MR to regulate body temp
–> Can let biochem processes slow down
–> For this reason, can go longer without food

2) Can exploit broader range of body sizes/shapes
–> Have freedom from heat-conserving body constraints
–> Can be very small

3) > Efficiency producing biomass
–> > amount of produced energy can go to building biomass rather than generating heat for maintaining temp

46
Q

Ectotherm Thermoregulation Strategy

A

Mainly Behavioral Thermoregulation
–> Will search environment for optimal temp

47
Q

Goldfish Thermoregulation Example

A

1) Goldfish placed into water tank with area of different temps
2) Goldfish explores tank
3) Selects region with the preferred temp and stays there

48
Q

Anole Lizard Thermoregulation Example

A

1) Sits on rock in sun to warm up during the day (Body temp can get higher than environmental temp!)
2) Burrows to prevent heat loss at night

49
Q

Terrestrial ectotherms deal with greater __________

A

Temperature fluctuations

(than aquatic ones since aquatic ectotherms have body temp directly equal to water temp)

50
Q

Thermal Acclimation

A

A physiological response that helps organisms adapt to LONG TERM temperature changes

51
Q

Maximum Critical Temperature

A

CTmax = Temp at which biochemical processes begin to fail (peak of the MR curve)

52
Q

Thermal Acclimation in Ectotherms

A

Can change their CTmax through selective enzyme synthesis

–> Produce different isoenzymes with varying optimal temps

53
Q

Isoenzyme

A

Related forms (isoforms) of the same enzyme

–> Catalyze the same rxns under different conditions

54
Q

Summer vs Winter Isoenzymes

A

Summer: Produce Isoenzymes with HIGHER optimal temp
(> CTmax)

Winter: Produce isoenzymes with LOWER optimal temp
(< CTmax)

55
Q

Acute Response

A

Rapid temp change = Rapid MR change

56
Q

Chronic Response

A

MR SLOWLY increases or decreases to optimal MR as new proteins with an optimal temp of the new environmental temp are produced

57
Q

Thermal acclimation involves TWO types of responses

A

1) Acute response

Followed by,

2) Chronic response

ONLY IF TEMP CHANGE REMAINS CONSTANT LONG TERM

58
Q

Endothermy

A

Use of INTERNAL heat to thermoregulate

Body temp remains relatively constant no matter the ambient temperature

59
Q

Relationship between body temp and ambient temp in endotherms

A

Body temp is NOT equal to ambient temp –> It is INDEPENDENT of environmental temperature

60
Q

Thermoneutral Zone

A

Range of AMBIENT TEMPS over which organism can thermoregulate WITHOUT increasing the MR

61
Q

How is body temp regulated in the TZ?

A

Through physiological changes such as vasodilation/constriction and other behavioral changes –> DO NOT increase MR!

62
Q

Vasoconstriction is best utilized for…

A

Heat retention; when it is colder outside

It INcreases the distance between the blood vessels and the heat exchanging surface

63
Q

Vasodilation is best utilized for…

A

Heat loss; when it is warmer outside

It DEcreases the distance between the blood vessels and the heat exchanging surface

64
Q

Thermogenesis (and the 2 main types)

A

Conversion of chemical energy into HEAT

2 main types:
1) Shivering thermogenesis
2) NON-Shivering thermogenesis

65
Q

Shivering thermogenesis

A

The co-contraction of muscles all over the body to generate A LOT of heat (as muscle contraction is highly inefficient with 75% of the energy expended being dissipated as heat)

66
Q

Non-Shivering thermogenesis

A

Metabolism of fat (mainly brown fat) to produce heat

67
Q

Endotherms utilize mechanisms of thermoregulation in TWO main categories…

A

1) Thermogenesis
2) Altering thermal conduction

68
Q

5 main processes utilized to alter thermal condutcion in endotherms

A

1) Decrease surface area (Available for heat transfer)
2) Increase size of organism
3) Insulation (fur/fat)
4) Decrease driving force (temp gradient)
5) Avoidance (behavioral regulation)

69
Q
A

BIO 203 (3 decks)

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