Respiration Lecture 14:Thermoregulation Flashcards Preview

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Flashcards in Respiration Lecture 14:Thermoregulation Deck (42)
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1

Thermoregulation

regulation of body temperature

2

2 main types of thermoregulation

1) homeotherms
2) poiliotherms

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Homeotherm

animal whose central temp is independent of a wide range of ambient temps (mode of thermoreg. where animal maintains a relatively stable temp. with little fluctuation)

4

Endoderm

control body temp through internal means such as shivering, fat burning, and panting

5

How does temp affect metabolic rxns?

Increased temp = increased metabolic rate due to increased enzyme reaction rates. Small changes in env. temp may enhance or depress metabolism

6

Poikilotherm

animal whose central temp differs little from ambient temp (internal temp dependent on the external conditions)

7

ectotherm

exchange heat with surroundings through activities such as basking in the sun and swimming. Use primarily BEHAVIORAL rather than METABOLIC means to regulate body temp

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Main difference between homeotherms/poikilotherms and endotherms/ectotherms

H/P are classified by how they respond to environmental temps, wheras E/E are classified by the source of heat determining the body temp

9

Under what temp. conditions is metabolic rate the highest in most animals?

At very low temperatures, and (to a lesser extent) very high temperatures. Metabolic rate production increases on either end outside of thermoneutral zone

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Thermoneutral zone

range of ambient temps without regulatory changes in metabolic heat production. Core temp of an animal is maintained constant while metabolic rate for heat prod. is minimal

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Energy Budget Equation***

Heat stored = Energy production - heat loss
S = M - W - [E - (R+C+D)]
where M = total metabolic rate, W=useful physical work, E= evaporative heat loss, and R+C+D= sum of radiant, convective, and conductive heat

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Radiation (R)

flow of energy b/w objects in space that depends only on the absolute temp. and the nature of the radiating surface. Energy passes from hot to cool object

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Conduction(D)

flow of heat from one object to another with which it is contact

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What is the inverse of conduction?

Insulation

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Convection (C)

transfer of heat dependent upon a liquid or gas medium b/w hot and cool objects. Heat loss is due to streams of air or fluid moving heat away from surface of the objects

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What are the main components of SENSIBLE heat transfer?

Radiation, conduction, and convection

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Evaporative heat exchange (E)

removal of heat from the surface of a liquid that is losing some of its molecules as gas. Les effective when surrounding air is humid

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What does INSENSIBLE heat transfer include?

Evaporative heat exchange

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What happens to evaporative heat loss as ambient temp increases?

Increases

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What kind of heat loss occurs when external temp is higher than internal core temp?

Evaporative heat loss

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2 main sources of evaporative heat loss

skin + respiratory tract

22

Panting

rapid, shallow breathing; a characteristic heat-losing rxn. Represents an increase in dead-space ventilation resulting in heat loss without necessarily increasing O2 uptake or CO2 loss.

23

What anatomical changes occur to increase panting related heat loss?

vascular engorgement of resp. tract and oral mucosa

24

Sweating and panting

use of sweating usually increases as use of panting decreases in animals. Sweating not effective enough to reg. temp at very high temps

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vasodilation

increasing diameter of superficial blood vessels allows for warming of the skin, thus increasing heat loss (opposite of vasoconstriction)

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fx and mech. of countercurrent exchange

helps trap body heat in the core and reduce heat loss. Mech = arteries carrying warm blood to extremities pass by vdein returning with cooler blood traveling back to the core, heating it to prevent a drop in core temp

27

Behavioral patterns during high ambient temp for mammals/birds

Anorexia, body extension, extra drinking, cold-seeking, decreased locomotion, etc.

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Behavioral patterns for low ambient temp for mammals/birds

Body flexing, huddling, heat-seeking, nest-building, increased locomotion, etc.

29

3 factors decreasing heat loss

1) shift in blood distribution
2) decrease in tissue conductance
3) counter-current heat exchange

30

What is the main control center for thermoreg?

Hypothalamus. Regulates "set point" for body temp

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