Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

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
Q

Define thermoneutral zone…?

A

zone in which endotherms do not need to change metabolic rate (heat production) to maintain core body temperature

26
Q

Inner core controlled by…?

A

abdo. & thoracic organs
CNS
skeletal muscles

27
Q

Outer shell controlled by…?

A

skin

sub-cut. fat

28
Q

Core temp = …?

A

difference between heat input & output

29
Q

What are the 2 thermoreceptors? Where are they found? How do they function?

A

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
Q

Where is the thermoregulatory centre in the brain found?

A

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
Q

Draw a flow chart illustrating the role of hypothalamus in thermoregulation…

A

slide 46…

32
Q

Explain ‘gain external heat’ (reduce loss to environment) scenario…

A
  • via solar radiation
  • heat gains thru ectothermic sources
  • thermoregulatory behaviours & anatomic features
33
Q

Explain ‘retain internal heat’ scenario…

A
  • 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
Q

Explain ‘generate more internal heat’ scenario…

A
  • definitive feature of endotherms

- specialised mechanisms

35
Q

Explain ‘lose excess internal heat/avoid gains from hot environments’ scenario…

A
  • avoidance behaviour
  • anatomical reduction in heat-gain
  • countercurrent exchange
  • increase evaporation
  • increased blood flow to skin (vasodilation)
  • decrease insulation
36
Q

List the roles skin plays in thermoregulation…

A
  • surface area
  • vascular structure
  • pigment
  • sweat glands
  • fur/hair
  • sub-cut. fat
  • temp. sensors
37
Q

ask about role of water in thermoregulation

A

slide 53

38
Q

Physiological responses to hot temperatures in horses…?

A
  • 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
Q

How much do horses need to sweat to maintain body temp. when environment temp. is 30 degrees…?

A 
walk = 1L/hr
trot = 15L/hr
canter = 20L/hr
gallop = 50L/hr
40
Q

Describe panting (polypnoea)…?

A
  • 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
Q

What are the physiological responses to cold…?

A

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
Q

Detail some ‘circulatory adjustments’ used in cold thermoregulatory responses…

A

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
Q

Mechanisms to increase heat production…?

A
  • 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
Q

Describe non-shivering thermogenesis…?

A

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
Q

How does brown fat differ from yellow fat?

A

brown fat contains: lipid (TAG) droplets, cytochromes (brown colour), lots of mitochondria
Energy released -> heat via SNS stim.

46
Q

Characteristics of hyperthermia…?

A
  • 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
Q

Characteristics of fever…?

A
  • 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
Q

What happens to thermoregulation during exercise?

A

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
Q

What happens during exercise in hot or humid climate? Use horse as an example…

A
  • 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
Q

Describe the process of heat stroke…?

A
  • 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
Q

At which range is body temp. at risk of seriously impairing cellular function & causing loss of consciousness?

A

> 41.5 - 42.5

52
Q

What are the differences between cold acclimation & cold acclimatisation?

A

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
Q

Describe climatic adaptation…?

A
  • 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
Q

Characteristics of hypothermia…?

A

heat output far&raquo_space; heat prod. -> decreased body temp.
hypothalamic regulation impaired if <29 degrees
cardiac arrest at 20 degrees
neonates can withstand cooling more than adults

55
Q

Characteristics of frostbite…?

A

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.
© 2024 Bold Learning Solutions. Terms and Conditions