T8 Thermoregulation

Question 1

Homeostasis

Answer 1

regulation of internal environment in face of changes in external environment

Question 2

Parameters of homeostasis

Answer 2

pH, water (volume and pressure of cells and blood plasma, osmoregulation), solutes, temperature, O2/CO2, heart rate.

Question 3

Negative feedback mechanisms

Answer 3

change in a variable under homeostatic control triggers response that opposes change

Question 4

Sensor

Answer 4

detects environmental conditions

Question 5

Integrator

Answer 5

analyzes signal from sensor, compares conditions to set point and activates appropriate effector

Question 6

Effector

Answer 6

causes a physiological change that opposes the deviation from the set pont

Question 7

Positive feedback mechanisms

Answer 7

change in a variable under homeostatic control triggers a response that amplifies change

Question 8

Thermo regulation .

Answer 8

regulating internal body temp

Question 9

Ambient Temperature

Answer 9

Ta

Question 10

Body temperature

Answer 10

Tb

Question 11

Heat generated by metabolism

Answer 11

body heat

Question 12

Heat can be exchanged with environments by conduction, convection, evaporation and radiation

Answer 12

body heat

Question 13

Have lower conductance due to Smaller SA/V ratios

Answer 13

Large organisms

Question 14

Homeotherm

Answer 14

maintains constant body temperature (Tb) independent of ambient temperature

Question 15

Heterotherm

Answer 15

Tb fluctuates

Question 16

Endotherm

Answer 16

uses metabolism to generate body heat (internal heat source)

Question 17

Ectotherm

Answer 17

acquires body heat from environment (external heat sources)

Question 18

Thermal Neutral Zone

Answer 18

temperature range around an animal where it can maintain its normal body temperature without using extra energy.

Question 19

Below TNZ (hypothermy)

Answer 19

Shivering, vasoconstriction, piloerection, decreasing surface area, decreasing exposure (huddling/burrowing)

Question 20

Above TNZ (Hyperthermy)

Answer 20

Panting, vasodilation, sweating, increasing surface area, decreasing exposure (to sun)

Question 21

Long term thermoregulation

Answer 21

Growing fur/adding fat, shedding, changing colour

Question 22

Behavioural Regulation of Conductance

Answer 22

Moving to optimize heat exchange with the environment to attain an ideal body temperature

Question 23

Exposure

Answer 23

movement into, or out of, the sun/wind. Surface area

Question 24

Grouping

Answer 24

huddling together to share radiation

Question 25

Dormancy

Answer 25

break in organism's life when it takes a rest, pausing growth and activity to save energy.

Question 26

Daily torpor

Answer 26

A short (6-8 hours) reduction in activity ~10C drop in Tb and a lower MR Reduce spending energy to stay warm (especially when food is scarce in winter)

Question 27

Hibernation

Answer 27

Tb regulated close to Ta • Massive reduction in MR • Lasts ~2 weeks before arousal • Requires massive heat generation for arousal • Awake for 1-2 days and then repeats

Question 28

Migration

Answer 28

Complete avoidance of poor environmental conditions

Question 29

Membrane Acclimation

Answer 29

Changes in ambient temperature and osmolarity cause fluctuations in the fluidity of cell membranes.

Question 30

Acclimated to 5C

Answer 30

lots of unsaturated fatty acids in membranes. At 25C membranes too fluid

Question 31

Acclimated to 25C

Answer 31

lots of saturated fatty acids in membranes. At 5C are too viscous

Question 32

Vasoconstriction

Answer 32

Decreases conductance with environment

Question 33

Vasoconstriction Endotherms

Answer 33

when cold to retain heat

Question 34

Vasoconstriction Ectotherms

Answer 34

when hot to retain heat

Question 35

Vasodilation

Answer 35

Increases conductance with environment

Question 36

Vasodilation Endotherm

Answer 36

when hot to release heat

Question 37

Vasodilation Ectotherm

Answer 37

when cold to increase heat gained from environment

Question 38

Internal insulation

Answer 38

Fat/blubber (internal insulation layer to slow rate of heat transfer)

Question 39

External insulation

Answer 39

Fur/feather (external insulation layer to slow rate of heat transfer)

Question 40

Piloerection

Answer 40

“fluffing” of fur/feather decreasing the rate of heat transfer by increasing thickness of insulation layer

Question 41

Dark fur

Answer 41

absorbs light and generates heat outside of insulation layer (easily lost to environment

Question 42

White fur

Answer 42

allows light to reach skin and generates heat inside of insulation layer (keeps arctic animals warmer)

Question 43

Sweating and panting

Answer 43

heat loss due to evaporation

Question 44

Cryoprotectants

Answer 44

molecules (glucose, glycerol) produced to lower freezing point

Question 45

Ice nucleating agents

Answer 45

antifreeze proteins prevents ice formation

Question 46

Shivering Thermogenesis

Answer 46

simultaneous action of antagonistic muscles generates heat without cause movement

Question 47

Non-Shivering Thermogenesis

Answer 47

molecular generation of heat

Question 48

Brown fat

Answer 48

special fat tissue loaded with special mitochondria (uses PMF for heat generation instead of ATP production)