Temperature 3 Flashcards

1
Q

what are the two types of ‘special’ endothermy (2)

A
  • temporal endothermy
  • regional endothermy
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2
Q

temporal endothermy

A
  • changes in body temperatures over time
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3
Q

regional endothermy

A
  • body temperature varies in regions of the body
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4
Q

temporal endothermy: example

A
  • hibernating animals
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5
Q

regional endothermy: examples (2)

A
  • billfish use heater organs near eyes
  • tunas and sharks retain heat in red muscle
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6
Q

what is the purpose of localized warming of skeletal muscle (2)

A
  • used for sustained locomotion
  • leads to faster contraction frequencies and more forceful contractions
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7
Q

white muscle function

A
  • used for bursts of locomotion used every so often
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8
Q

red muscle function

A
  • used for sustained locomotion
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9
Q

where is the red muscle located in fish without regional endothermy and what are the implications (2)

A

-red muscle located externally along the body wall
- leads to muscle being cooled by external passing water

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10
Q

where is red muscle located in fish with regional endothermy and what are the implications (2)

A
  • red muscle is internalized and insulated by white muscle
  • heat is better controlled and protected from heat loss by passing water
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11
Q

what contributes to the elevated red muscle endothermy of tuna an sharks (2)

A
  • heat produced in the muscle is retained there due to internalization and insulation
  • rete mirabile
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12
Q

rete mirabile (2)

A
  • extensive countercurrent arrangement of arterioles and venules
  • transmits heat from venous to arterial blood to retain heat
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13
Q

in the rete mirabile arrangement, which vessels get warmed/cooled (2)

A
  • the venous blood is cooled by incoming arterial blood
  • the arterial blood is warmed by exiting venous blood
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14
Q

what do we know about tuna red muscle that alludes to their ability to practice regional endothermy

A
  • red muscle is always warmer than ambient temperature
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15
Q

what do we know about tuna red muscle that alludes to their ability to actively regulate their temperature (2)

A
  • red muscle warms faster than it cools
  • if rates were the same, the muscle would simply be a conductor
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16
Q

what determines the control of temperature and rate of muscle warming/cooling in tune

A
  • the rete mirabile system
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17
Q

how might warm muscles affect oxygen unloading in humans (2)

A
  • right shift of the OEC, stabilization of the T state and increase in P50
  • would result in enhanced O2 unloading in humans
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18
Q

how might warm muscles affect oxygen unloading in fish (2)

A
  • fish Hb are not temperature sensitive, so it has no effect
  • may be beneficial to protect the fish from excessive O2 unloading
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19
Q

what cells are the heater tissue of billfish eyes composed of

A
  • modified, non-contractile muscle cells
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20
Q

what is the mechanism used to create heat in heater tissue cells (3)

A
  • T-tubule activates Ca2+ release from sarcoplasmic reticulum into cytoplasm
  • stimulates ATP-consuming metabolic processes
  • mitochondria produce more ATP
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21
Q

what mechanism is used to retain heat in the heater organ

A
  • carotid rete system (countercurrent exchange) localizes heat to eyes and brain
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22
Q

how does cranial temperature change during dives in billfish

A
  • cranial change stays relatively constant even though water temperature drops
23
Q

why do billfish have a heater organs near their eye/brain (2)

A
  • allows them to see better (higher Q10)
  • makes them better predators, especially against pray at lower depths where it is colder
24
Q

what terms are used to describe the thermal zones/limits in homeotherms (3)

A
  • thermoneutral zone
  • upper critical temperature (UCT)
  • lower critical temperature (LCT)
25
homeotherms: thermoneutral zone (2)
- range of temperature optimal for physiological processes - metabolic rate is minimal in this range
26
homeotherms: upper critical temperature (2)
- metabolic rate increases as animal induces a physiological response to prevent overheating - upper limit of the thermoneutral zone
27
homeotherms: lower critical temperature (2)
- metabolic rate increases to increase heat production - lower limit of the thermoneutral zone
28
homeotherms: what occurs outside of the LCT (2)
- metabolic rate increases for thermogenesis - onset of hypothermia occurs when animal can no longer maintain homeostasis of body temperature
29
homeotherms: what occurs outside of the UCT (2)
- metabolic rate increases for active cooling - onset of hyperthermia occurs when animal can no longer maintain homeostasis of body temperature
30
what terms are used to describe the thermal zones/limits in poikilotherms (3)
- preferred temperature - incipient lethal temperature - range of tolerance
31
poikilotherms: preferred temperature
- ambient temperature for optimal physiological function
32
poikilotherms: incipient lethal temperature (2)
- ambient temperature at which 50% of animals die - animals have an incipient upper lethal temperature (IULT) and an incipient lower lethal temperature (ILLT)
33
poikilotherms: range of tolerance
- range of ambient temperatures between the IULT and the ILLT
34
what terms describe the thermal tolerance of animals (2)
- eurytherm - stenotherm
35
eurytherm
- can tolerate a wide range of ambient temperatures
36
stenotherm
- can tolerate only a narrow range of ambient temperatures
37
eurytherms vs stenotherms: thermal niches
- eurytherms can occupy a greater number of thermal niches than stenotherms
38
thermal tolerance: aerobic scope (3)
- represents the energy available for any activity above resting - changes depending on the temperature - aerobic scope = maximal metabolic rate - resting metabolic rate
39
thermal tolerance: Topt
- temperature where the maximum aerobic scope occurs
40
thermal tolerance: Tcrit
- temperature where there is no aerobic scope (animal is dead at these temperatures)
41
what holds membrane lipids together
- Van der Waal's forces
42
how are membranes affected by temperature
- membrane fluidity is affected by temperature
43
membrane fluidity: low temperatures
- membrane lipids solidify, decreasing membrane fluidity
44
membrane fluidity: high temperatures
- increase memebrane fluidity
45
what do changes in membrane fluidity affect (2)
- affect protein movement - increased membrane fluidity results in increased protein movement
46
how do membrane fluidities change in animals living in different temperatures with different body temperatures
- membrane fluidity is maintained relatively constant across animals at their respective body temperatures
47
what term is used to describe how animals can maintain membrane fluidity at different temperatures
- homeoviscious adaptation
48
homeoviscous adaptation
- maintain membrane fluidity at different temperatures by changing composition of membrane lipids
49
what is the mechanisms of homeoviscous adaptation (4)
- fatty acid chain length - saturation - phospholipid classes - cholesterol content
50
homeoviscous adaptation: fatty acid chain length
- shorter chains increase fluidity because of reduced interactions with neighbouring fatty acids
51
homeoviscous adaptation: saturation
- more double bonds (unsaturation) increase fluidity due to their introduction of kinks into the tail of the phospholipids
52
homeoviscous adaptation: phospholipid classes (3)
- phosphatidylcholine (PC): decrease fluidity - phosphatidyethanlamine (PE): increase fluidity - involves change in the phospholipid head group
53
homeoviscous adaptation: cholesterol content
- higher cholesterol content prevents solidifying when membrane is cooled
54
membrane remodeling (2)
- used to achieve homeoviscous adaptation - describes the rapid modulation of membrane fluidity by decreasing saturation in existing phospholipids, or by synthesizing new phospholipids and inserting them into the membrane while taking unwanted phospholipids out