Module 1: Heat Transfer + Thermoreg.

Question 1

Heat

Answer 1

Kinetic energy embedded in molecules (molecular motion)

Question 2

Temperature

Answer 2

An index of molecule motion (the average kinetic energy)

–> Hot = High KE
–> Cold = Low KE

Question 3

Heat Transfer

Answer 3

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

–> Occurs wherever there is a temperature difference

–> Has 4 main methods

Question 4

Methods of Heat Transfer (4)

Answer 4

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

Question 5

Conduction

Answer 5

Heat transfer through STATIONARY matter by PHYSICAL CONTACT

Question 6

Driving Force of Conduction

Answer 6

Temperature gradient (difference in temp between the two objects)

Question 7

T1 > T2

Answer 7

Heat flows from T1 to T2

Question 8

T1 < T2

Answer 8

Heat flows from T2 to T1

Question 9

T1 = T2

Answer 9

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

Question 10

Heat always flows from…

Answer 10

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

Question 11

Rate of Heat Transfer Equation

(and simplified form)

Answer 11

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

Flow = Ease of Movement * Driving Force

Question 12

Ease of Movement

Answer 12

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

Question 13

Ease of Movement (part of the equation)

Answer 13

(K*A) / L

Question 14

What is “K” in the heat flow equation?

Answer 14

K = Thermal Conductivity (of the material)

Question 15

What is “A” in the heat flow equation?

Answer 15

A = Surface area of contact

Question 16

What is “L” in the heat flow equation?

Answer 16

L = Length/distance between objects

Question 17

Convection

Answer 17

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

Question 18

Two main types of convection:

Answer 18

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

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

Question 19

Free Convection

Answer 19

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

(Ex: Hot air rising)

Question 20

Forced Convection

Answer 20

Environmental medium movement is externally/physically induced

(Ex: Fan moving the air)

Question 21

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

Answer 21

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

Question 22

Effect of boundary layers on convection

Answer 22

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)

Question 23

Radiation

Answer 23

Electromagnetic Waves

–> All objects both ABSORB and EMIT electromagnetic waves

Question 24

Heat Loss from Radiation

Answer 24

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

Question 25

Heat Gain from Radiation

Answer 25

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

Question 26

Evaporation

Answer 26

The transformation (of water) from liquid to gas

Question 27

Heat of Vaporization

Answer 27

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"

Question 28

Evaporative Cooling

Answer 28

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

Question 29

Thermal Budget

Answer 29

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

Question 30

Heat gain mechanisms

Answer 30

**External Exchange: ** 1) Conduction 2) Convection 3) Radiation **Internal: ** 4) Metabolic Rate (endogenous heat production)

Question 31

Heat loss mechanisms

Answer 31

**External Exchange:** 1) Conduction 2) Convection 3) Radiation 4) Evaporation **Internal:** N/A

Question 32

Thermoregulation

Answer 32

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

Question 33

Why must body temperature be regulated?

Answer 33

So that rxns. occur at a sufficient rate

Question 34

If body temperature is too high...

Answer 34

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

Question 35

If body temperature is too low...

Answer 35

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

Question 36

Maintaining body temp at a specifific optimal temp allows...

Answer 36

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

Question 37

Reaction Rate and Temperature Relationship

Answer 37

Reaction rate increases exponentially with temperature increase

Question 38

3 main strategies for thermoregulation:

Answer 38

1) Ectothermy 2) Endothermy 3) Heterothermy

Question 39

Ectothermy

Answer 39

Use of external heat to thermoregulate; **body temp varies WITH environmental temp** AKA "Poikilotherms", "Cold Blooded", "Variable Tb"

Question 40

Organisms that are Ectotherms

Answer 40

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

Question 41

In ectotherms, body temp is ____________ to environmental temp

Answer 41

PROPORTIONAL Tb = Tamb

Question 42

Ectotherms: Metabolic rate and environmental temp relationship

Answer 42

MR varies with Tamb

Question 43

Ectotherms: High environmental temp

Answer 43

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

Question 44

Ectotherms: Low environmental temp

Answer 44

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

Question 45

Advantages of Ectothermy (3)

Answer 45

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

Question 46

Ectotherm Thermoregulation Strategy

Answer 46

Mainly Behavioral Thermoregulation --> Will search environment for optimal temp

Question 47

Goldfish Thermoregulation Example

Answer 47

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

Question 48

Anole Lizard Thermoregulation Example

Answer 48

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

Question 49

Terrestrial ectotherms deal with greater __________

Answer 49

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

Question 50

Thermal Acclimation

Answer 50

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

Question 51

Maximum Critical Temperature

Answer 51

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

Question 52

Thermal Acclimation in Ectotherms

Answer 52

Can change their CTmax through selective enzyme synthesis --> Produce different isoenzymes with varying optimal temps

Question 53

Isoenzyme

Answer 53

Related forms (isoforms) of the same enzyme --> Catalyze the same rxns under different conditions

Question 54

Summer vs Winter Isoenzymes

Answer 54

Summer: Produce Isoenzymes with HIGHER optimal temp (> CTmax) Winter: Produce isoenzymes with LOWER optimal temp (< CTmax)

Question 55

Acute Response

Answer 55

Rapid temp change = Rapid MR change

Question 56

Chronic Response

Answer 56

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

Question 57

Thermal acclimation involves TWO types of responses

Answer 57

1) Acute response Followed by, 2) Chronic response ONLY IF TEMP CHANGE REMAINS CONSTANT LONG TERM

Question 58

Endothermy

Answer 58

Use of INTERNAL heat to thermoregulate Body temp remains relatively constant no matter the ambient temperature

Question 59

Relationship between body temp and ambient temp in endotherms

Answer 59

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

Question 60

Thermoneutral Zone

Answer 60

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

Question 61

How is body temp regulated in the TZ?

Answer 61

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

Question 62

Vasoconstriction is best utilized for...

Answer 62

Heat retention; when it is colder outside It INcreases the distance between the blood vessels and the heat exchanging surface

Question 63

Vasodilation is best utilized for...

Answer 63

Heat loss; when it is warmer outside It DEcreases the distance between the blood vessels and the heat exchanging surface

Question 64

Thermogenesis (and the 2 main types)

Answer 64

Conversion of chemical energy into HEAT 2 main types: 1) Shivering thermogenesis 2) NON-Shivering thermogenesis

Question 65

Shivering thermogenesis

Answer 65

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)

Question 66

Non-Shivering thermogenesis

Answer 66

Metabolism of fat (mainly brown fat) to produce heat

Question 67

Endotherms utilize mechanisms of thermoregulation in TWO main categories...

Answer 67

1) Thermogenesis 2) Altering thermal conduction

Question 68

5 main processes utilized to alter thermal condutcion in endotherms

Answer 68

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)