Thermoregulation

Question 1

What is homeostasis?

Answer 1

homeo (similar) stasis (state)

It it a dynamic process that is regulated by how the organism can change its behaviour/metabolism to maintain its internal environment to an acceptable range

Question 2

what are the parameters that organisms must control?

Answer 2

pH,
water (volume and pressure of cells and blood plasma, osmoregulation),
solutes,
temp,
O2/Co2,
heart rate,
input/output

Question 3

What is a Negative feedback mechanism?

Answer 3

A change in a variable under homeostatic control, triggers a response that opposes the change

Question 4

sensor:

Answer 4

detects environmental conditions
ex. temp: nerve endings in skin

Question 5

Integrator:

Answer 5

analyzes signal from sensor, compares conditions to the set point and activated an appropriate effector
ex. brain, hypothalamus

Question 6

Effector:

Answer 6

causes a physiological change that opposes the deviation from the set point
ex. skeletal muscle, sweat glands

Question 7

stimulus:

Answer 7

something that causes something else to happen, develop, or become more active

Question 8

Negative feedback mechanisms work to

Answer 8

reestablish homeostasis

Question 9

Positive feedback mechanisms are

Answer 9

change in variable under homeostatic control triggers a response that amplifies the change
good for achieving an outcome once

Question 10

Positive feedback mechanisms push a system

Answer 10

away from homeostasis (produces more and more)
Amplifies the change
not homeostatic

Question 11

Thermoregulation is

Answer 11

regulating the internal body temperature
Temperature has a huge impact on
energy budgets

Question 12

_________ has a huge impact on
energy budgets

Answer 12

Temperature

Question 13

Ambient temperature (Ta)
Body temperature (Tb)
What’s the same and what’s different for ectotherms and endotherms?

Answer 13

for ectotherms the ta and Tb are the same

for endotherms the ta and Tb are different (bc endotherms create their own heat)

Question 14

heat is generated by

Answer 14

metabolism

Question 15

heat can be exchanged with the environment by

Answer 15

conduction, convection, evaporation, and radiation

Question 16

Endotherms use the heat made by
metabolism for ______

Answer 16

thermoregulation

Question 17

Ectotherms let the heat generated by metabolism ________

Answer 17

dissipate into the environment

Question 18

Body heat can be regulated by

Answer 18

changing the rate of heat gain and loss

Question 19

Rate of heat exchange is called

Answer 19

conductance

Question 20

Large organisms have ______ due to _______

Answer 20

lower conductance (rate of heat exchange)
smaller SA:V ratios

Question 21

Small organisms have ________ due to ______

Answer 21

higher conductance (rate of heat exchange)
larger SA:V ratios

Question 22

homeotherm:

Answer 22

maintains a constant body temp (Tb) independent of ambient temperature (Ta),

can be human or earthworm.

very stable temperature

most endotherms are homotherms

Question 23

Heterotherms:

Answer 23

(Tb) fluctuates with (Ta).
mostly ectotherms, but some can be endotherms
ex. Freshwater fish whose (Tb) changes with seasonal changes in the water temperature (Ta).

Question 24

Endotherms:

Answer 24

uses metabolism to generate body heat (internal heat generation)

Question 25

Ectotherm:

Answer 25

aquires body heat from the environment, do generate heat via metabolism (but don’t keep or use that heat) external heat source ex. Ice fish are homeotherms and ectotherms because they live in a stable environment (ice water)

Question 26

By reducing your ____ you don't have to eat as much to maintain a _____ (heterotherms that are endotherms)

Answer 26

internal temp higher body temp

Question 27

at low temps, enzymes are

Answer 27

inactive

Question 28

at high temps, enzymes are

Answer 28

denatured

Question 29

the optimum temp for enzyme activity is

Answer 29

just before enzymes are denatured

Question 30

as an endotherms Ta increases, its Tb _____

Answer 30

stays relatively the same

Question 31

as an ectotherms Ta increases, its Tb ______

Answer 31

Increases proportionally tb=ta

Question 32

Where does thermoregulation occur:

Answer 32

Above and below the TNZ (thermal neutral zone) occurs in order to regulate body temp

Question 33

In the graph of "Ambient Temperature (Ta) and Metabolic Rate (RMR) in a Homeothermic Endotherm" the steeper the line, the:

Answer 33

greater conductance

Question 34

In the graph of "Ambient Temperature (Ta) and Metabolic Rate (RMR) in a Homeothermic Endotherm" when the line is straight, that is the:

Answer 34

thermal neutral zone minimal metabolic regulation occurs

Question 35

In the graph of "Ambient Temperature (Ta) and Metabolic Rate (RMR) in a Homeothermic Endotherm" below the thermal neutral zone is

Answer 35

hypothermy Shivering, vasoconstriction, piloerection, decreasing surface area, decreasing exposure (huddling/burrowing)

Question 36

In the graph of "Ambient Temperature (Ta) and Metabolic Rate (RMR) in a Homeothermic Endotherm" above the thermal neutral zone is

Answer 36

(Hyperthermy) Panting, vasodilation, sweating, increasing surface area, decreasing exposure (to sun),

Question 37

longer term solution to regulate body temp, that are not instantaneous are

Answer 37

Growing fur/adding fat, shedding, changing color

Question 38

Low conductance is an adaptation for

Answer 38

heat retention (in the arctic bc its cold)

Question 39

High conductance is an adaptation for

Answer 39

heat loss (in the tropical bc its hot)

Question 40

in "Ambient Temperature (Ta) and Metabolic Rate (SMR) in a Heterothermic Ectotherm" graph, as Ta increase, what stages does the SMR go through?

Answer 40

hypothermia lethargy activity hyperthermia

Question 41

the thermal neutral zone for homeotherms is between the :

Answer 41

lower critical temp and higher critical temp

Question 42

what is Behavioural regulation of conductance:

Answer 42

Moving to optimize heat exchange with the environment to attain an ideal body temp

Question 43

what are the four groups of Behavioural regulation of conductance?

Answer 43

exposure grouping dormancy migration

Question 44

exposure is:

Answer 44

Movement into or out of the sun/wind Surface area ex. organism going in the shade

Question 45

Grouping is:

Answer 45

huddling together to share radiation ex. bats in a cave

Question 46

Dormancy (daily torpor) is:

Answer 46

reduce spending energy to stay warm (short 6-8 hr reduction) “nocturnal” torpor helps conserve energy, high metabolic rate is “turned down” nightly/seasonally to reduce NRG requirements in cold, drought, famish environments.

Question 47

dormancy (Hibernation) is:

Answer 47

when TB regulated close to TA, huge reduction in metabolic rate, lasts 2 weeks before arousal, requires huge heat generation for arousal, awake for 1-2 days then repeats.

Question 48

Migration is:

Answer 48

the Complete avoidance of poor environmental conditions Ex. Whales, birds, caribou, butterflies

Question 49

Physiological regulation of conductance is:

Answer 49

Making physiological adjustments to optimize heat exchange with environment to attain ideal body temp

Question 50

ways to physiologically regulate conductance:

Answer 50

Acclimation Blood Flow Insulation Fur Length and Colour Change Sweating/panting Cryoprotectants Shivering Thermogenesis Non shivering thermogenesis

Question 51

Membrane acclimation: is

Answer 51

accumulation of changes in every cell acclimates the organism to their environment

Question 52

Blood flow is in two groups:

Answer 52

Vasoconstriction: decreases conductance with environment (Endotherms, when cold to retain heat, ectotherms, when hot to retain heat) Vasolidation: increases conductance with environment (Endotherms, when hot to release heat, ectotherms, when cold to release heat gained from environment)

Question 53

Insulation:

Answer 53

internal (fat, blubber): internal insulation layer that slows the rate of heat transfer External (fur/feathers): external insulation layer to slow rate of heat transfer Plioerection: the fluffing of fur/feathers to decrease rate of heat transfer by increasing thickness of insulation layer

Question 54

Fur/feather thickness/length regulates conductance by

Answer 54

giving better insulation animals increase amount/thickness of fur between summer and winter

Question 55

Fur coloration (dark fur) helps by

Answer 55

absorbing light, generates heat outside of insulation layer, easily lost to environment

Question 56

Fur coloration (white fur) helps by

Answer 56

White fur: let’s light reach skin, generates heat inside of insulation layer, keeps arctic animals warmer

Question 57

Fur coloration (hollow hairs) helps by

Answer 57

Hollow hairs: allow radiation to transmit down hair shaft, so that baby seals and polar bears gain most solar heat

Question 58

Sweating and panting regulate heat by:

Answer 58

evaporation causing heat loss

Question 59

Cryoprotectants

Answer 59

Molecules (glucose, glycerol) produced to: 1. Lower freezing point 2. Allow ice to form in extracellular spaces, but not internally metabolic rate is zero but they're still alive (makes them colder)

Question 60

Ice-nucleating agents are when

Answer 60

Antifreeze proteins prevent ice formation

Question 61

Shivering thermogenesis is when

Answer 61

Simultaneous action of antagonistic muscles generating heat without causing movement (shivering to make heat)

Question 62

Non-shivering thermogenesis:

Answer 62

special fat tissue (brown fat) that is loaded with special mitochondria Instead of using PMF for ATP production, it’s used to generate “heat” (the protons go through UCP1) Used to raise Tb (especially in newborns)