Respiration Lecture 14:Thermoregulation

Question 1

Thermoregulation

Answer 1

regulation of body temperature

Question 2

2 main types of thermoregulation

Answer 2

1) homeotherms

2) poiliotherms

Question 3

Homeotherm

Answer 3

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)

Question 4

Endoderm

Answer 4

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

Question 5

How does temp affect metabolic rxns?

Answer 5

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

Question 6

Poikilotherm

Answer 6

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

Question 7

ectotherm

Answer 7

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

Question 8

Main difference between homeotherms/poikilotherms and endotherms/ectotherms

Answer 8

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

Question 9

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

Answer 9

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

Question 10

Thermoneutral zone

Answer 10

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

Question 11

Energy Budget Equation***

Answer 11

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

Question 12

Radiation (R)

Answer 12

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

Question 13

Conduction(D)

Answer 13

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

Question 14

What is the inverse of conduction?

Answer 14

Insulation

Question 15

Convection (C)

Answer 15

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

Question 16

What are the main components of SENSIBLE heat transfer?

Answer 16

Radiation, conduction, and convection

Question 17

Evaporative heat exchange (E)

Answer 17

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

Question 18

What does INSENSIBLE heat transfer include?

Answer 18

Evaporative heat exchange

Question 19

What happens to evaporative heat loss as ambient temp increases?

Answer 19

Increases

Question 20

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

Answer 20

Evaporative heat loss

Question 21

2 main sources of evaporative heat loss

Answer 21

skin + respiratory tract

Question 22

Panting

Answer 22

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.

Question 23

What anatomical changes occur to increase panting related heat loss?

Answer 23

vascular engorgement of resp. tract and oral mucosa

Question 24

Sweating and panting

Answer 24

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

Question 25

vasodilation

Answer 25

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

Question 26

fx and mech. of countercurrent exchange

Answer 26

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

Question 27

Behavioral patterns during high ambient temp for mammals/birds

Answer 27

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

Question 28

Behavioral patterns for low ambient temp for mammals/birds

Answer 28

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

Question 29

3 factors decreasing heat loss

Answer 29

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

Question 30

What is the main control center for thermoreg?

Answer 30

Hypothalamus. Regulates “set point” for body temp

Question 31

How is heat release triggered?

Answer 31

Activation of warm receptors increases activity in ANTERIOR hypothalamus resulting in peripheral vasodilation, sweating, panting

Question 32

How is heat storage triggered?

Answer 32

Activation of cold receptors increases activity of the POSTERIOR hypothalamus resulting in heat production, shivering, and non-shivering thermogenesis

Question 33

Effector mechanisms

Answer 33

try to get temperature back to set point. Include vasomotor, metabolic, and sudomotor (activates sweat glands) mechanisms

Question 34

Reciprocal inhibition

Answer 34

Warm and cold hypothalamic regulator centers inhibit one another. (negative feedback loop)

Question 35

Where are thermoreceptors located?

Answer 35

In skin and hypothalamus

Question 36

Fever

Answer 36

a change in set point (the body temp is regulated at a higher set point). Different than acclimatization

Question 37

How do mammals and birds acclimatize?

Answer 37

increase insulation, cells produce heat-shock proteins

Question 38

How do poiliotherms acclimatize?

Answer 38

respond at cellular lvl: increase/alter enzyme production, change membrane lipid arrangement to maintain fluidity,produce cryoproteins or stress-induced heat-shock proteins

Question 39

Cryoprotein

Answer 39

prevents ice formation in cells

Question 40

Temporal heterothermy

Answer 40

body temp and metabolic rate are elevated only during activity.

Question 41

Regional heterothermy

Answer 41

animals maintain different temp. zones in body

Question 42

Kleptothermy

Answer 42

sharing or stealing of each other’s body heat