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BIOL241 > Topic 8 - Thermoregulation > Flashcards

Topic 8 - Thermoregulation Flashcards

(56 cards)

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1
Q

Homeostasis

A

regulation of an internal environment in the face of changes in the external environment.

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2
Q

Negative Feedback

A

A change in variable triggers a response that opposes the change
LEADS TO HOMEOSTASIS

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3
Q

Positive Feedback

A

change in variable triggers a response that amplifies the change
DOES NOT LEAD TO HOMEOSTASIS

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4
Q

How is metabolic energy used to maintain homeostasis, using temperature regulation as an example

A

activity on hot day results in rise in skin and body temp –> change is detected by temp cells in the skin –> neurons in hypothalamus recieve sensory info and determine if reaction is required–> info is sent along a motor pathway–> metabolically generated heat is conducted to evaporative surfaces, panting is produced

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5
Q

Ectotherm

how does it get its heat?

A

acquires body heat from environment, generate metabolic heat but dont keep it

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6
Q

Endotherm

A

uses metabolism to generate body heat

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7
Q

homeotherm

A

maintains constant body temperature, independent of ambient temperature

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8
Q

heterotherm

A

body temperature fluctuates with ambient temperature (ex fish whose temp changes seasonally)

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9
Q

How can homeostasis be regulated?

A

Change in behavior or metabolism to maintain internal environment within certain range.

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10
Q

In the regulation of homeostasis, what are parameters that organisms control?

A

pH, water, volume and pressure of cells and blood plasma, osmoregulation, solutes, temperature, O2/CO2, heart rate

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11
Q

With feedback mechanisms, what are the steps?

A

SSIE: stimulus, sensor, integrator, effector

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12
Q

Stimulus

A

external or internal change in a regulated factor

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13
Q

Sensor

A

detects the change in condition

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14
Q

Integrator

A

compares condition to its set point, activates effector

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15
Q

Effector

A

physiological change that returns factor to its set point

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16
Q

Explain temperature regulation as an example of homeostasis

SSIE

A

Stimulus: change in temperature of skin
Sensor: temp detection nerves in the skin
Integrator: Hypothalamus
Effector: Muscle tissue, vasculature, sweat glands

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17
Q

explain the positive feedback mechanism of childbirth

A

Stimulus: head of baby pushes against cervix
Sensor: stretch receptors in cervix
Integrator: pituitary gland releases oxytocin
Effector: oxytocin causes the uterus to contract (cervix to dilate), puts more pressure on the sensors

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18
Q

Why is thermoregulation important?

A

regulating internal body temperature impacts energy budgets

ambient temperature (Ta) determines how much energy is spent regulating body temperature (Tb)

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19
Q

What happens to body heat in endotherms

generation exchange regulation

A

Heat generation: metabolism
Heat exchange: conduction, convection, evaporation and radiation
Regulation: Tb is regulated by changing conductance

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20
Q

Conductance

A

the rate of heat exchange

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21
Q

what is the relationship between mass and conductance? and why?

A

As body mass increases, conductance decreases

due to the low SA:V ratio. if there is more SA, there is more conductance. Less SA per mass, risks losing less heat

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22
Q

convection

A

air/liquid for heat transfer

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23
Q

conduction

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A

direct contact heat transfer

24
Q

evaporation

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A

loss of heat when water changes from liquid to gas

25
What is the strategy of an endotherm + heterotherm
change body temperature seasonally (eg hibernation)
26
what is the strategy of an endotherm + homeotherm
Behavioural: seek cool or warmth Physiological: sweating, panting, shivering
27
what is the strategy of a homeotherm+ectotherm
seek or live in stable environments
28
what is the strategy of a heterotherm+ectotherm
behavioural: move between sun and shade physiological: adjust metabolic rate based on ambient temp
29
Regional Heterothermy
animals with different temperatures in different parts of their bodies ex: tuna with high core body temp and exterior muscles at ocean temp
30
what is the metabolic consequence of endothermy?
higher mass-specific RMR than ectotherms Recall: as body mass increases, mass-specific RMR declines
31
Why is temperature important for metaboilism? | enzymes?
enzyme activity varies with temperature, influencing body temperature enzymes at low temps are inactive, reach ideal, high temps they denature
32
What is the relationship between temperature, metabolism, and performance?
Temperature drives metabolism, which drives performance
33
How does the response to ambient temperature differ between ecto and endotherms
as temperature increases, endotherm stays constant, until denaturation, ectotherm has positive correlation
34
What is the response of a homeothermic endotherm to changes in ambient temperature?
RMR starts high, decreases at slope related to conductance, reaches BMR (this is the thermal neutral zone), MR increases to cool down, after a certain point it is hyperthermy
35
What is the TNZ
thermo neutral zone is where energy is not needed for regulation
36
Heterothermic ectotherm response to changes in ambient temp
starts low, increases constantly (lethargy then activity where temp is optimum), increases too far (hyperthermia)
37
What are strategies to regulate temperature | for homeotherms
Below TNZ, thermogenesis (things like shivering, vasoconstriction, decreasing exposure through huddling/burrowing) Above TNZ, ACTIVE COOLING, panting, sweating
38
What are behavioral regulations of conductance
Moving to optimize heat exchange with environment Changing exposure Grouping Migration Dormancy
39
What is torpor
short 6-8 hour reduction in activity, drop in body temp, lower metabolic rate - reduces energy use to stay warm
40
What is hibernation
usually done by small mammals, as large SA to V ratio makes it easier to quickly change body temp, awake for 1-2 days periodically
41
Why do animals migrate?
Temperature regulation - seeking certain ambient conditions recquires less energy expenditure to maintain body temp
42
Physiological regulation of conductance
acclimation, blood flow, insulation, fur length and color change, sweating/panting, cryoprotectants, shivering thermogenesis, non-shivering thermogenesis
43
Acclimation
changes to physiological processes that respond (typically to seasonal) temperature changes.
44
What does Acclimation look like for animals, cell membranes and enzymes
Animal - more enzyme to compensate lower efficiency Cell membrane - altered viscosity Enzyme - change conformation to be more efficient
45
Give an example of acclimation with membrane viscosity
If acclimated to 25C, and put at 5C temp, phospholipids will be less saturated to decrease viscosity If acclimated to 5 and put at 25C, phospholipids will be more saturated to increase viscosity
46
How can blood flow be regulated to affect conductance with environment
Vasoconstriction - vessels have less diameter, less blood flow, less heat moves to surface Vasodilation
47
Explain vasoconstriction, its relation to conductance for endo and ectotherms
Decreases conductance with environment Endotherms: when cold, to retain heat Ectotherms: when hot, to retain heat
48
Explain vasodilation its relation to conductance for endo and ectotherms
increases conductance with environment Endotherm: when hot, to release heat Ectotherm: when cold, to increase heat gained from environment (ex hot rocks)
49
Insulation - how is it a strategy for changing conductance
can slow the rate of heat transfer internal: fat/blubber external: fur/feathers
50
Why do some animals have thicker fur in winter
provides more insulation
51
How is fur colouration a thermoregulatory strategy?
Dark fur absorbs light, generates heat outside insulation. Heat is lost to environment more easily by convection White fur allows light to reach skin, generates heat inside insulation layer, skin stays warmer as fur protects its loss
52
What is the purpose of sweating and panting
Heat loss due to evaporation panting increases ventilation which increases heat loss
53
What are cryoprotectants
Molecular strategy used by ectotherms Molecules (like glucose or glycerol) are produced to lower freezing point Antifreeze properties allow ice to form in extracellular spaces but not internally, prevent sharp edges from crystallization
54
What are the two types of thermogenesis
Shivering and Not-shivering
55
Shivering Thermogenesis
muscles move rapidly to generate heat, but no movement
56
Non-shivering thermogenesis
fat is metabolized by the mitochondria - convert energy into heat rather than ATP

BIOL241 (6 decks)

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