Animal Lecture 10: Thermal Phys

Front 1

what is thermal strategy?

Back 1

animal chooses temp where phys is optimal. try to keep a narrow range. ectotherms stablish a stable temp. by changing their behavior

Front 2

thermal

Back 2

refers to heat energy

Front 3

temperature

Back 3

measurement of heat energy

Front 4

Ta

Back 4

ambient temp of environment

Front 5

Tb

Back 5

body temp

Front 6

comparison of heat capacity water and air

Back 6

water > air

Front 7

heat capacity

Back 7

a measure of the amount of energy required to increase the temp. of a material; differs for diff. materials

Front 8

4 factors animals face in thermal env.

Back 8

1. diff ave. temps
2. diff extremes
3. diff rates in which change occurs
4. diff altitudes and diff. oxygen pressures

Front 9

give an example of extreme temp change

Back 9

desert (50 degress per day) vs. here (temperate) (10-20 degrees per day)

Front 10

what region has the most narrow temp. change?

Back 10

tropical, 20-30C. makes sense bc most diversity of animals

Front 11

aquatic regions are generally ___ temp envirnoments

Back 11

stable

Front 12

5 components of heat flux

Back 12

1. metabolic heat production
2. conduction
3. convention
4. radiation
5. evaporation

Front 13

heat transfer is (+) if ext temp is __ than int. temp

Back 13

>

Front 14

heat transfer is (-) if ext. temp is __ than ext. temp

Back 14

<

Front 15

conduction

Back 15

the mechanism by which energy is transferred. direct transfer of kinetic energy of molecular motion; takes place between physical bodies that are in contact w one another

Front 16

conductivity

Back 16

a property of the material that describes how well that material transfers energy

Front 17

conductivity of water is __ than air

Back 17

>

Front 18

conductance

Back 18

a measure of how easily energy flows

Front 19

resistance

Back 19

1/conductance. insultation is a measure of resistance
the higher the insulation the lower the conductance

Front 20

common insulators

Back 20

internal insulation (under the skin): blubber
ext insulation (on body surface): hair, feathers

Front 21

convection

Back 21

mass movt of fluid contributes to renewal of the fluid at the boundary; acc. heat transfer

Front 22

example of convection

Back 22

how fluid the medium is, wind in the air, mvt of water

Front 23

radiation

Back 23

heat transfer tkaes place int he absence of direct contact; due to emission of electromagnetic radiation

Front 24

evaporation

Back 24

always removes heat from the body; depends on convection and radiation (radiation is how much heat the body releases and conv. actually removes it into the ext. environment)

Front 25

evaporation rate

Back 25

diff. between vapor pressure of water on body surface and vapor pressure of water in air determines rate of water loss

Front 26

thermal gradient

Back 26

explains why conduction is always going two ways, until equilibrium

Front 27

greater mass = _ heat production

Back 27

>

Front 28

greater mass = _ vol to mass ratio

Back 28

lower

Front 29

greater mass = __ heat loss

Back 29

slower

Front 30

example of extreme high and low vol are ratio

Back 30

large ratio: tree shrew
small ratio: elephant

Front 31

describe struc of polar bear

Back 31

large to produce lots of heat but small limbs to reduc heat loss

Front 32

few animals can live outside of ___ range

Back 32

0-45 degree C

Front 33

icnr temp. ___ rxn rate

Back 33

incr

Front 34

Q10 concept

Back 34

Q10 = rate at (T+10degreeC)/rate at T

Front 35

what does Q10=5 mean?

Back 35

rate incre 5 fold

Front 36

what does Q10=1 mean?

Back 36

rate is not temp sensitive

Front 37

what determines membrane fluidity?

Back 37

1. variation in fatty acid chain length - shorter is more fluid
2. vary degree of saturation
-less saturated, more fluid
3. types of phospholipids
more chloresterol => more fluid as temp goes down

Front 38

ectothermy

Back 38

most ancient, body temp relies on the env. include all invertebrates, fishes, ampgibians and reptiles (5 billion ya)

Front 39

endothermy

Back 39

more recnet, phys themoregulation by producting heat through metabolic means, includes brids and mammals (65-200 million years ago)

Front 40

hemeothermy

Back 40

regulates body temp. at a constant level. i.e. fish, humans does not explain how)

Front 41

poikilothermy

Back 41

body temp changes. i.e. black cap chickadee in aa. temp drops at night. also endothermic

Front 42

heteorthermy

Back 42

regulates body temp at a constant levels some of the time. example: bumblebee, bats

Front 43

regional heterothermy

Back 43

regulates part of the body a ta a constant level some of the time. usually this happens in the limbs. example tuna

Front 44

eurythermal

Back 44

wide tolerance limits

Front 45

stenothermal

Back 45

narrow tolerance limits

Front 46

acute temp changes - cause the most

Back 46

dramatic effects on physiology

Front 47

example of acute temp changes

Back 47

day/night temperature changes have profound effects on metabolic rates

Front 48

chronic temperature changes

Back 48

result in long-term physiological readjustments in order to maintain metabolic processes at a reasonably constant level

Front 49

example of chronic temp changes

Back 49

metabolic compensation, which allows ectotherms to maintain a fairly stable metabolic rate through different seasons

Front 50

how is metabolic compensation achieved?

Back 50

expression of different isozymes that code for different optima

Front 51

graph of metabolic compensation

Back 51

winter and summer temp fish can have the same metabolic rate at their optimum temp

Front 52

ectotherms are not primitive...

Back 52

they just have different life history strategies than endotherms

Front 53

examples of ectotherms controlling rates of cooling and heating

Back 53

heat in water fastest
cool in water the next fastest
heat in air the next bc air conducts slower
cool in air bc resist cold and less conductive (ask)

Front 54

behavioral thermoregulation

Back 54

most important; they choose microclimates that allow them to keep body temp as close to optimum as possible

Front 55

the H+ bonds an enzyme has

Back 55

the more stable the enzyme will be

Front 56

as temp drops

Back 56

___becomes more stable

Front 57

animals with a lower preferred temperature tend to be active

Back 57

earlier in the day and earlier in the year

Front 58

benefits of preferred temperature

Back 58

1 divides up habitat to some extent
2 temperature at which animals physiologically operate best correlates with preferred temperature

Front 59

strategy to find optimum temperature

Back 59

noose and goose read

Front 60

does the animel always choose its thermal optimum

Back 60

no-must consider other factors - gasous environment, osmoregulation, risk of predation,etc

Front 61

how do ectotherms thermoregulate?

Back 61

ectotherms can control the rates of heating and cooling

Front 62

in general ectotherms do not

Back 62

produce enough heat metabolically to keep themselves warm

Front 63

most ectotherms are capable of sensing temperature, but

Back 63

not all can do something about it (i.e. fishes)

Front 64

ectotherms have temperature sensors in the same part of the brain as

Back 64

endotherms (neurons in the hypothalamus)

Front 65

thermal optimum =

Back 65

preferred body temp

Front 66

B Isozyme

Back 66

enzymes with same catalytic function but different temperature optima

Front 67

metabolic compensation allows ectotherms to

Back 67

maintain similar metabolic rates at very different ambient temperatures

Front 68

2 main functions of thermal phys mechanisms

Back 68

1 control rates of change in temp; since most ectotherms heat faster than they cool, they have mechanisms to reduce heat loss
2 to generate heat during periods of metabolic demand (muscle activity, locomotion)

Front 69

vasomotor control

Back 69

alterations in blood flow to skin (decr flow to reduce heat loss, incr flow to incr heat loss)

Front 70

panting

Back 70

inc heat loss

Front 71

changing color

Back 71

alter body reflectance (incr or decr heat absorption)

Front 72

regional heterothermy

Back 72

countercurrent heat exchange (large fish use rete mirable to decr heat loss)

Front 73

changing to a dark color

Back 73

absorbs heat

Front 74

changing to a lighter color

Back 74

reflects heat

Front 75

vasoconstriction

Back 75

response to cold temp, less blood flow towards skin and less heat conductance

Front 76

vasodilation

Back 76

response to high temperature; more blood flow to the skin and high heat conductance, heat leaves body

Front 77

example of generating heat before metabolic demand

Back 77

large insect warm up before flight by inc muscle activity

Front 78

dormancy

Back 78

hibernation and estivation

Front 79

hibernation

Back 79

a state of regulated hypothermia, lasting several days or weeks that allows animals to conserve energy during the winter

Front 80

estivation

Back 80

a state of dormancy similar to hibernation. animals that estivate spend a summer inactive and insulated against heat, to avoid the potentially harmful effects of the season. some animals may estivate to conserve energy when their food and water supply is low

Front 81

example of organisms that estivate

Back 81

california red-legged frog, couch's spadefoot toad

Front 82

freeze avoidance and freeze tolarance

Back 82

although not found in the earth coldest environments, many have to deal with extreme cold winter temperatures

Front 83

freeze avoidance: antifreeze proteins

Back 83

winter and summer fish have diff freezing points bc winter fish have antifreeze proteins added to their blood. in place of salt so it does not change blood osmolarity

Front 84

freeze tolerance

Back 84

some animals can tolerate freezing a significant proportion of their bodies

Front 85

mechanism for freeze tolerance

Back 85

add cryoprotectants like glycerol inside their cells to minimize cellular damage when they thaw

Front 86

example of freeze tolerance

Back 86

northern frog species form glycerol in their toes after they have frozen

Front 87

advantages of ectothermy

Back 87

low energy flow, able to exploit habitats that mammal and birds cannot. better to deal w shortage of food, water, and oxygen. shrew eats its body weight every 12 hours while ratlle snake eats once ever 6 months (low maintainance)

Front 88

what is an endotherm (3)

Back 88

1 produce heat through phy means
2 have insulation that maintains heat w/in body
3 maintain Tb diff from Ta. only time Tb leaves range is during fever or hibernation (torpor)

Front 89

how many times have endotherms evolved?

Back 89

2 (birds and mammals) maybe 3 (dinosaurs)

Front 90

what came first: insulation or heat production?

Back 90

heat production which is very costly, i.e. dinosaurs velocirator, deinonychus

Front 91

dinosaur bone is more related to ___ or ___ bone in cross section than it is to typical ectothermic ___ bone

Back 91

mammalian, avian, reptilian

Front 92

3 ways that endotherms generate heat

Back 92

1 metabolism (futile cycling; plasma membranes of endotherms are "leaky" compared w ectotherms)
2 digestion
3 muscle activity (locomotion, shivering)

Front 93

2 ways endothemrs conserve heat

Back 93

1 vasocontriction
2 insulation

Front 94

advantages of endothermy

Back 94

1 tighter homeostatic control
2 can live in colder environments
3 can remain active at all times

Front 95

disadvantages of endothermy

Back 95

1 must obtain more food
2 must maintain a higher metabolic rate

Front 96

describe graph of endotherm body temp and metabolic rate curve

Back 96

1 body temp is constant except for extremes
2 metabolic rate decr as temp incr

Front 97

heat production in endotherms results from

Back 97

the chemical rxns that occur in all cells

Front 98

basal metabolic rate

Back 98

set by the cost-of-living

Front 99

2 ways heat production in endotherms can be incre

Back 99

1 incr muscle activity (shivery thermogenesis)
2 actions of several hormones (non-shivering thermogenesis)

Front 100

heat flux

Back 100

a measure of transfer of heat energy

Front 101

behavorial thermoregulatory adjustments in endotherms

Back 101

1 change location
2 change posture

Front 102

phys thermoregulatory adjustments in endotherms

Back 102

insulation, vasomotor control

Front 103

examples of insulation

Back 103

piloerection, changes in thickness of insulation, seasonal changes in fur thickness

Front 104

what controls vasomotor control?

Back 104

sympathetic branch of the autonomic nervous system

Front 105

two blood vessel pathways of vaso motor control

Back 105

AV shunt and arteriole

Front 106

shivering thermogenesis

Back 106

involuntary muscle activity incr heat production

Front 107

non-shivering thermogenesis

Back 107

incr metabolic rate, controlled by hormones

Front 108

metabolic pathways that generate heat in endotherms

Back 108

thyroid thermogenesis, catecholamines

Front 109

thyroid thermogenesis

Back 109

thyroid hormone acts to regulate production of Na+/K+ATPase that hydrolyzes ATP and releases heat in the process

Front 110

catecholamines

Back 110

act on adipose tissue to incr lipolysis

Front 111

brown fat

Back 111

non-shivering thermogenesis example, some animals have this specialized adipose tissue, it does not store fat it generates heat

Front 112

what controls brown adipose tissue? (BAT)

Back 112

sympathetic nervous system, activated by nonepinephrine, epinephrine

Front 113

where is the thermostat of endotherms?

Back 113

in the CNS (central nervous system)

Front 114

how does CNS sense changes in Tb?

Back 114

central thermosensitive neurons

Front 115

how does CNS sense changes in Ta?

Back 115

peripheral thermosensors in skin

Front 116

where is the CNS in mammals?

Back 116

in the hypothalamus (preoptic area)

Front 117

where is the CNS in birds?

Back 117

in the spinal cord

Front 118

diagram when its below set point

Back 118

1 vasoconstriction
2 BAT
3 shivering

Front 119

diagram when its above set point

Back 119

1 vasodilation
2 sweating
3 panting

Front 120

example, endotherms that also use counter current heat exchange

Back 120

canadian goose, pacific bottlenose dolphin

Front 121

function of webbed feet in geese

Back 121

vein network to conserve body heat and maintain core Tb

Front 122

4 problems for endotherms

Back 122

1 energy acquisition
2 heat generation
3 heat conservation and dissipation
4 water conservation

Front 123

2 problems with warm climates

Back 123

1 dissipating heat (esp keeping brain cool)
2 heat loss

Front 124

how do we counter dissipating heat

Back 124

countercurrent heat exchange, sweating, panting

Front 125

how do we counter water loss

Back 125

extensive sinuses to cool excurrent air (in many desert adapted species), concentrated urine due to long loop of henle

Front 126

problem with cold climates

Back 126

insulation

Front 127

example of seal

Back 127

conductive heat loss to the surrounding medium

Front 128

migration

Back 128

imp for birds, deal with cold climate

Front 129

temp during hibernation

Back 129

no lower than 4 degree C but arctic squirrels can go to -2 degrees

Front 130

animals that have temporal heterothermy (daily torpor)

Back 130

bird, black chickedee