Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

ASC171 - Final exam modules > Thermoregulation > Flashcards

Thermoregulation Flashcards

1
Q

Define thermoregulation

A

process by which animals maintain internal temp within a tolerable range - involves form, function & behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Thermal energy derived from…?

A

chemical processes in body -> mechanical energy => heat energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Body temp is a measure of…?

A

thermal energy held within molecules of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Thermal energy influences…?

A

chemical interactions
macromolecular structure
biochemical reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3 main ways animals regulate body temperature?

A
  1. behavioural
  2. biochemical
  3. physiological
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is a constant temperature so important for higher animals?

A

for efficient brain function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Characteristics of endotherms…?

A
  • generate heat by metabolism
  • core internal temp relatively constant
  • active at greater range of external temps
  • more energetically expensive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Characteristics of ectotherms…?

A
  • rely on external heat sources
  • most invertebrates, fishes, amphibians, non-avian reptiles
  • tolerate greater variations in internal temps
  • more energetically efficient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Difference between a poikilotherm & homeotherm?

A

poikilotherm -> internal temp varies with environment

homeotherm -> internal temp. relatively constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 4 methods of heat exchange?

A
  • conduction
  • convection
  • radiation
  • evaporation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe each method of heat exchange…

A

conduction - heat flux (transfer) of thermal energy from one region of object/fluid to another
convection - transfer of thermal energy between an object and external fluid/gas that is moving
radiation - emission of electromagnetic radiation
evaporation - fluid (sweat) draws thermal energy from body surface as liquid molecules -> gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the factors regulating thermoregulation?

A
  • Surface area (greater SA:BW -> faster heat loss)
  • hair coat (insulation -> lower heat loss)
  • environmental conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which methods of heat exchange rely on a temperature gradient?

A

radiation, convection, conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Low humidity would cause more, or less evaporation?

A

more (low humidity = drier external environment -> absorbs more moisture)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Wind speed influences which methods of heat exchange?

A

convection & evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 5 general adaptations that help animals thermoregulate?

A
  1. insulation
  2. circulatory adaptations
  3. cooling by evaporative heat loss
  4. behavioural responses
  5. adjusting metabolic heat production
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe insulation…?

A

a major thermoregulatory adaptation in birds & mammals

encompasses feathers, fur, skin, blubber to reduce heat flow from animal and its environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe circulatory adaptations…?

A
  • regulation of blood flow near the body surface significantly affects thermoregulation
  • many endo’s & some ecto’s can alter blood flow between core & skin
  • vasodilation -> increase blood flow in skin -> heat loss
  • vasoconstriction -> decreases blood flow to skin -> minimises heat loss
  • COUNTERCURRENT EXCHANGE - transfer heat from fluids (eg blood vessels) that flow in opposite directions - important mechanism for reducing heat loss eg. fins of bottle nose dolphin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe cooling by evaporative heat loss…?

A
  • Many animals that lose heat via evaporation of water in sw

eg’s: panting -> cooling effect in mammals & birds; sweating or bathing -> moistens skin -> cooling effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe some behavioural responses adaptations…?

A

Endo’s & ecto’s both use behavioural responses for thermoreg. (moving into shade on hot day -> minimise risk of overheating)
Terrestrial invertebrates have postures -> minimise or maximise absorption of solar heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe & give examples of adjusting metabolic heat production…?

A

Heat prod. increased by muscle activity (eg. shivering or moving)
animals can regulate body temp. by adjusting rate of metabolic heat prod.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Define BMR…?

A

basal metabolic rate - metabolic rate of endotherm at rest at a “comfortable” temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Define SMR…?

A

standard metabolic rate - metabolic rate of an ectotherm at rest at a specific temp

24
Q

T or F - endotherms have a much lower metabolic rate than ectotherms of comparable size

A

false - endo’s have much HIGHER metabolic rates than ecto’s

25
Define thermoneutral zone...?
zone in which endotherms do not need to change metabolic rate (heat production) to maintain core body temperature
26
Inner core controlled by...?
abdo. & thoracic organs CNS skeletal muscles
27
Outer shell controlled by...?
skin | sub-cut. fat
28
Core temp = ...?
difference between heat input & output
29
What are the 2 thermoreceptors? Where are they found? How do they function?
Skin (peripheral thermoreceptors) - temp. sensitive neurons (mostly cold); skin cold receptors (rate of temp. decrease); skin receptors for heat (initiate heat loss when skin temp. high) Viscera (central thermoreceptors) - eg. drinking large volumes cold fluids -> stimulate cold receptors in GIT -> body heat-conserving mechanisms initiated??????? check this...
30
Where is the thermoregulatory centre in the brain found?
Hypothalamus - heat-sensitive neurons located in preoptic area of hypothalamus -> increase firing rate in response to minor increases in local temp. -> info -> posterior pituitary -> appropriate behavioural & physiological responses -> changes in heat prod. and/or dissipation
31
Draw a flow chart illustrating the role of hypothalamus in thermoregulation...
slide 46...
32
Explain 'gain external heat' (reduce loss to environment) scenario...
- via solar radiation - heat gains thru ectothermic sources - thermoregulatory behaviours & anatomic features
33
Explain 'retain internal heat' scenario...
- behaviour (burrowing) - insulation (hair) - reduced blood flow to skin (vasoconstriction) - countercurrent exchangers in circulation - larger body sizes - decrease heat loss via conduction, radiation & sometimes convection & evaporation
34
Explain 'generate more internal heat' scenario...
- definitive feature of endotherms | - specialised mechanisms
35
Explain 'lose excess internal heat/avoid gains from hot environments' scenario...
- avoidance behaviour - anatomical reduction in heat-gain - countercurrent exchange - increase evaporation - increased blood flow to skin (vasodilation) - decrease insulation
36
List the roles skin plays in thermoregulation...
- surface area - vascular structure - pigment - sweat glands - fur/hair - sub-cut. fat - temp. sensors
37
ask about role of water in thermoregulation
slide 53
38
Physiological responses to hot temperatures in horses...?
- sweat glands all over body - during ex. sweat first in areas that cannot lose heat by radiation (under tack, between hind legs) - next sweat areas -> neck, chest, flanks
39
How much do horses need to sweat to maintain body temp. when environment temp. is 30 degrees...?
``` walk = 1L/hr trot = 15L/hr canter = 20L/hr gallop = 50L/hr ```
40
Describe panting (polypnoea)...?
- rapid, shallow breaths -> increased rate of flow air -> nasal passages -> heat picked up from body -> to environment - usually increased rate of salivation - increased rate of evaporative cooling (if humidity not too high) - stimulated by reflex & central - horses & cattle -> evaporative cooling in UPPER RESP. TRACT, not lungs
41
What are the physiological responses to cold...?
primary - decrease heat loss (physical reg.) secondary - increase heat prod. (chemical reg.) BEHAVIOURAL RESPONSES & increased insulation - posture (curled up position) - piloerection (traps layer of air next to skin -> increase insulation) - increase fur growth - winter coat -> increase insulation
42
Detail some 'circulatory adjustments' used in cold thermoregulatory responses...
VASOCONSTRICTION -> decreases peripheral blood flow -> decrease skin temp. -> decrease temp. gradient between skin & environment - functional insulation of skin increased due to decreased convective heat loss of perfusing blood - mediated centrally by drop in CNS temp. + reflexes stimulated by cold receptors in skin COUNTER-CURRENT HEAT EXCHANGE SYSTEM -> cold venous blood moves adjacent to warm arterial blood going to extremities -> continuous heat exchange in these vessels -> minimises heat loss to environment This mechanism + skin vessel vasoconstriction -> shifts returning venous blood -> deep channels (from superficial) -> increases efficiency of counter-current heat exchange system
43
Mechanisms to increase heat production...?
- lower critical temp. -> heat-retaining mechanisms no longer adequate -> heat prod. must increase varies between species (eg sheep & cattle lowest CT thus most able to stand cold) - shivering -> principal mechanism of increased heat prod. -> increased activity of skeletal muscles however, increased heat prod. can also occur without shivering called NON-SHIVERING THERMOGENESIS
44
Describe non-shivering thermogenesis...?
increased heat prod. without shivering (der) induced by CIRCULATING HORMONES Adr, NA & thyroxine -> increased heat prod. by increasing metabolism BROWN FAT in new-born animals - ability to store energy for quick release in large amounts. Also, repeated cold exposures -> increase brown fat stores hibernation -> lower body temp. + slower breathing & lower metabolic rate (eg. badger, fat-tailed lemur)
45
How does brown fat differ from yellow fat?
brown fat contains: lipid (TAG) droplets, cytochromes (brown colour), lots of mitochondria Energy released -> heat via SNS stim.
46
Characteristics of hyperthermia...?
- UNREGULATED rise in body temp. in response to environmental conditions of extreme heat & high humidity - may also occur when evaporative mechanisms impaired due to dehydration - heat gains in body exceed bodies capacity to lose heat thru EVAPORATION - whole body cooling required -> reverse effect
47
Characteristics of fever...?
- elevation of animals thermoregulatory set-point - infection -> increased body temp. -> enhances leukocyte activity - increased pyrogens & PGEs -> inhibit warm-sensitive neurons -> decrease firing rate -> increase set-point -> heat conservation & production til new set point reached - animal response - shivering, peripheral vasoconstriction, piloerection, huddling - eventually metabolism of pyrogen -> decrease temp. via sweating & vasodilation
48
What happens to thermoregulation during exercise?
metabolic rate increases as core temp. increases muscles -> lots of heat 25% energy consumed by muscles -> force 1st response -> peripheral vasodilation -> increase blood flow to skin. (a result of efferent arm of -ve feedback response to increased core temp.) 1.5 - 2 degrees increase in core temp. -> decrease blood flow to liver (25%), kidney (30%), GIT (>50%)
49
What happens during exercise in hot or humid climate? Use horse as an example...
- horse - high humidity -> impairs evaporation (should hose horse to aid cooling) - heat dissipation requires good blood supply to skin -> diverts blood away from muscles -> decrease muscle perfusion -> decrease O2 delivery -> anaerobic metabolism -> fatigue easier - ELECTROLYTES & H2O -> lost with ineffective sweating in humid enviorn's -> dehydration & fatigue -> heat stroke
50
Describe the process of heat stroke...?
- hot humid weather -> ineffective evaporative cooling - strenuous exercise -> dangerous - dogs in cars -> saturate air with water vapour -> further heat loss impossible -> increase body temp. -> increase metabolic rate -> panting, sweating -> dehydration & circulatory collapse -> skin cooling harder
51
At which range is body temp. at risk of seriously impairing cellular function & causing loss of consciousness?
>41.5 - 42.5
52
What are the differences between cold acclimation & cold acclimatisation?
Acclimation - PRIMARILY shift from shivering -> non-shivering thermogenesis (1st 2-3 weeks of cold exposure); brown fat stores may increase; effect lost when placed in hot (30 degree) environment for 4 days Acclimatisation - MAINLY increased INSULATION (thicker fur coat & more sub-cut. fat); lower critical temp. than animals not acclimatised; gradually increased insulation takes over need for heat generation of acclimation
53
Describe climatic adaptation...?
- body temp. of homeotherms -> no adaptive change ie. rectal temp. same in tropics & arctic regions - arctic animals have insulation & blubber & do not increase temp. until environment temp. very low - lower critical temp. eg. arctic fox -30 degrees
54
Characteristics of hypothermia...?
heat output far >> heat prod. -> decreased body temp. hypothalamic regulation impaired if <29 degrees cardiac arrest at 20 degrees neonates can withstand cooling more than adults
55
Characteristics of frostbite...?
ice crystals form -> disrupt tissue integrity -> gangrene | PREVENTED by vascular SM dilation in extreme cold -> inflow of warm blood

ASC171 - Final exam modules (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions