Temperature 3

Question 1

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

Answer 1

• temporal endothermy
• regional endothermy

Question 2

temporal endothermy

Answer 2

• changes in body temperatures over time

Question 3

regional endothermy

Answer 3

• body temperature varies in regions of the body

Question 4

temporal endothermy: example

Answer 4

• hibernating animals

Question 5

regional endothermy: examples (2)

Answer 5

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

Question 6

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

Answer 6

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

Question 7

white muscle function

Answer 7

• used for bursts of locomotion used every so often

Question 8

red muscle function

Answer 8

• used for sustained locomotion

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

rete mirabile (2)

Answer 12

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

Question 13

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

Answer 13

• the venous blood is cooled by incoming arterial blood
• the arterial blood is warmed by exiting venous blood

Question 14

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

Answer 14

• red muscle is always warmer than ambient temperature

Question 15

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

Answer 15

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

Question 16

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

Answer 16

• the rete mirabile system

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

what cells are the heater tissue of billfish eyes composed of

Answer 19

• modified, non-contractile muscle cells

Question 20

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

Answer 20

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

Question 21

what mechanism is used to retain heat in the heater organ

Answer 21

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

Question 22

how does cranial temperature change during dives in billfish

Answer 22

• cranial change stays relatively constant even though water temperature drops

Question 23

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

Answer 23

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

Question 24

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

Answer 24

• thermoneutral zone
• upper critical temperature (UCT)
• lower critical temperature (LCT)

Question 25

homeotherms: thermoneutral zone (2)

Answer 25

- range of temperature optimal for physiological processes - metabolic rate is minimal in this range

Question 26

homeotherms: upper critical temperature (2)

Answer 26

- metabolic rate increases as animal induces a physiological response to prevent overheating - upper limit of the thermoneutral zone

Question 27

homeotherms: lower critical temperature (2)

Answer 27

- metabolic rate increases to increase heat production - lower limit of the thermoneutral zone

Question 28

homeotherms: what occurs outside of the LCT (2)

Answer 28

- metabolic rate increases for thermogenesis - onset of hypothermia occurs when animal can no longer maintain homeostasis of body temperature

Question 29

homeotherms: what occurs outside of the UCT (2)

Answer 29

- metabolic rate increases for active cooling - onset of hyperthermia occurs when animal can no longer maintain homeostasis of body temperature

Question 30

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

Answer 30

- preferred temperature - incipient lethal temperature - range of tolerance

Question 31

poikilotherms: preferred temperature

Answer 31

- ambient temperature for optimal physiological function

Question 32

poikilotherms: incipient lethal temperature (2)

Answer 32

- ambient temperature at which 50% of animals die - animals have an incipient upper lethal temperature (IULT) and an incipient lower lethal temperature (ILLT)

Question 33

poikilotherms: range of tolerance

Answer 33

- range of ambient temperatures between the IULT and the ILLT

Question 34

what terms describe the thermal tolerance of animals (2)

Answer 34

- eurytherm - stenotherm

Question 35

eurytherm

Answer 35

- can tolerate a wide range of ambient temperatures

Question 36

stenotherm

Answer 36

- can tolerate only a narrow range of ambient temperatures

Question 37

eurytherms vs stenotherms: thermal niches

Answer 37

- eurytherms can occupy a greater number of thermal niches than stenotherms

Question 38

thermal tolerance: aerobic scope (3)

Answer 38

- represents the energy available for any activity above resting - changes depending on the temperature - aerobic scope = maximal metabolic rate - resting metabolic rate

Question 39

thermal tolerance: Topt

Answer 39

- temperature where the maximum aerobic scope occurs

Question 40

thermal tolerance: Tcrit

Answer 40

- temperature where there is no aerobic scope (animal is dead at these temperatures)

Question 41

what holds membrane lipids together

Answer 41

- Van der Waal's forces

Question 42

how are membranes affected by temperature

Answer 42

- membrane fluidity is affected by temperature

Question 43

membrane fluidity: low temperatures

Answer 43

- membrane lipids solidify, decreasing membrane fluidity

Question 44

membrane fluidity: high temperatures

Answer 44

- increase memebrane fluidity

Question 45

what do changes in membrane fluidity affect (2)

Answer 45

- affect protein movement - increased membrane fluidity results in increased protein movement

Question 46

how do membrane fluidities change in animals living in different temperatures with different body temperatures

Answer 46

- membrane fluidity is maintained relatively constant across animals at their respective body temperatures

Question 47

what term is used to describe how animals can maintain membrane fluidity at different temperatures

Answer 47

- homeoviscious adaptation

Question 48

homeoviscous adaptation

Answer 48

- maintain membrane fluidity at different temperatures by changing composition of membrane lipids

Question 49

what is the mechanisms of homeoviscous adaptation (4)

Answer 49

- fatty acid chain length - saturation - phospholipid classes - cholesterol content

Question 50

homeoviscous adaptation: fatty acid chain length

Answer 50

- shorter chains increase fluidity because of reduced interactions with neighbouring fatty acids

Question 51

homeoviscous adaptation: saturation

Answer 51

- more double bonds (unsaturation) increase fluidity due to their introduction of kinks into the tail of the phospholipids

Question 52

homeoviscous adaptation: phospholipid classes (3)

Answer 52

- phosphatidylcholine (PC): decrease fluidity - phosphatidyethanlamine (PE): increase fluidity - involves change in the phospholipid head group

Question 53

homeoviscous adaptation: cholesterol content

Answer 53

- higher cholesterol content prevents solidifying when membrane is cooled

Question 54

membrane remodeling (2)

Answer 54

- 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