E3: Temp. Regulation Flashcards
_____ reactions within the body are extremely sensitive to temp.
Biochemical
All enzymes have a(n) _____ _____ _____ for normal function.
Optimal temperature range
When is an enzyme impared in regards to temperature?
When the temp. is above or below the optimal temp. range
What happens when temp. is too low?
- metabolic process slows
- reduced energy (less ATP) for normal activity and reproduction
What happens when temp. is too high?
- metabolic reactions become unbalanced
- enzymes denatured and non-functional
What are the two options for temp. regulation?
1) find a habitat without temp. extremes
2) develop means to stabilize their metabolism independent to environmental temp. extremes
Define poikilothermic
Ectothermic
Define homeothermic
endothermic
For poikilothermic organisms, body temp. is _____ with changing environmental temps.
fluctuating
More animals are _____thermic.
Poikilothermic or ectothermic
For Poikilothermic organisms, heat loss is _____ to gain by motabolism.
equal
How to Poikilothermics produce heat energy?
As a result of chemical reactions
What is an example of a Poikilothermic exploiting their environment behavioally?
Sun basking
For homeothermic organisms, body temp. is _____ with changing environmental temps.
independently regulated or constant
How do homeothermics produce body heat?
From within
What kind of animals are homeothermic?
birds, mammals, few non-avial reptiles and fast swimming fishes
What is an advantage of Homeothermics to Poikilothermics?
Can exploit habitats unsuitable for ectotherms (colder environemnts)
Which type of thermic hibernates?
homeothermic, but can remain active in winter
What do Poikilothermics do when they are too hot?
- seek shade
- stand above hot ground surfaces (not lay down)
- decrease body surface exposed to sun
What do Poikilothermics do when too cold?
- seek out the sun
- increase surface area exposed to sun
- lay on hot surfaces
What is temperature compensation?
The adjustment of metabolic rates to the prevailing temperature.
How do Homeothermics maintain temp?
By the delicate balance between heat production and heat loss
Body temp range for mammals.
36C - 38C (97F - 101F)
Body temp range for birds.
40C - 42C (104F - 108F)
Do Homeothermics or Poikilothermics need to comsume more food and why?
Homeothermics because heat production is directly tied to food intake
How is heat produced by metabolism for Homeothermics?
- oxidation of foods (cellular repiration)
- basal cellular metabolism
- muscle contraction
What are the 4 forms of heat loss?
- radiation
- conduction
- convection
- evaporation of water
Describe radiation heat loss
by long wavelength into surrounding surface
Describe conduction heat loss
Heat loss conducting to contact surfaces
- ground water, etc
Describe convection heat loss
Heat loss by air movement across surface body
Describe evaporation of water heat loss
- from outside body surface (sweating)
- From respiratory surface (beathing)
What does Fossorial mean?
Below the ground (burrowing, hiding below ground)
What are some adaptations for hot environemnts?
- Fossorial behavior
- Nocturnal behavior
How do large desert ungulates prevent water loss and overheating?
- light colored fur to reflect sun
- insulating fur (thick)
- increased convection and conduction on underside with thin fur
- insulating fat concentrated in hump (keep heat out and in)
- evaporative cooling (sweating and panting)
- large eart to shade and increase surface area for heat loss
What does ungulate mean?
Hoofed animal that regergitate and chew their partially digested food
What are the two primary mechanisms to maintain temperatures in cold environments?
1) decreased heat conductance
2) increased heat production
Decreased heat conductance mechanisms
- increased fur and feather thickness
- increase thickness of subcutaneous fat
- increase thickness of fat layers on foot pads that are in contact with cold surfaces
How do extremities help with heat loss?
- allowed to cool far below body temp
- countercurrent heat exchange
- feet can rach very low temps (near freezing, muscles are closer to body and digit control is by tendons)
- fats in extremitis have lower melting point (30C lower than other body fat)
What methods of augmented muscluar activity prevent heat loss?
- increased exercise
- shivering
This forces an increase in ATP and heat production by aerobic cellular respiration
Non-shivering thermo genesis
Brown fat metabolism (fat abundant with mitochondria and blood supply)
Where is brown fat found?
Near chest, axillary regions, and near kidneys (more so in babies)
How does brown fat metabolism work?
The uncoupling protein acts to uncouple the production of ATP during oxidative phosphorylation to produce heat rather than ATP.
When food consumption cannot meet the energy demand or during seasonal changes and food shortages, what do some Birds and Mammals do?
Adaptive Hypothermia
What does adaptive hypothermia allow?
The body temp to call to decresae the loss of heat to the environment
How long can adaptive hypothermia last for?
hours to months depending on the species
What is daily torpor and give an example of an organism that does this.
Drop in temp during inactivity and sleep
- hummingbirds
Hibernation vs torpor.
Hibernation is voluntary, torpor is involuntary
What is hibernation?
A prolonged and controlled state or dormancy
What happens to core temp when in hibernation?
Drops to a degree or less above ambient temps.
How do organisms produce heat during the arousal period of hibernation?
shivering and non-shivering thermogenesis
Prolonged sleep vs hibernation?
Prlonged sleep organisms can be awakended due to moderate maintenance of normal temp.
Hiberating organisms cannot be awakened due to needing to go though the arousal process
Estivation definition
Dormancy during hot or dry periods
Why do organisms go into estivation?
Water and food are scarce, decreases the metabolism
