Thermoregulation Flashcards
Poikilothermic
Temperature conformer: body temperature conforms to the external temperature (ex: lizard) (varied heat)
- ectothermic
- bradymetabolic: relatively low metabolic rate
- regulate temperature through behavioral processes
Homeothermic
Temperature Regulator: internal temperature says the same even when outside changes (similar heat)
- temperature regulated to some extent by autonomic and/or behavioral processes
- ectothermic & endothermic
- tachymetabolic: relatively high metabolic rate
Tachymetabolic
relatively high metabolic rate
Bradymetabolic
relatively low metabolic rate
ectothermic
outside-hot
-regulate by outside means
endothermic
within-hot
Young Homeotherms
May not be able to regulate their own body temperature at birth (ex: rats and human babies cannot thermoregulate outside of their comfort zone, unlike lambs)
Thermoregulatory control systems (Homeotherm)
- controlled system (environment heat exchange impacts this): core temperature
- controlling elements: thermoregulatory effectors
feedback: peripheral & deep-body thermoreceptors - comparator: CNS compares temperature to set point
Conduction
Transfer of heat between objects:
- warmer to cooler (concentration gradient)
- that are in direct contact with one another
Convection
-The transfer of heat energy by air currents.
Evaporation
-Conversion of a liquid into a gaseous vapor
- a process that requires heat
– the heat of
vaporization –
-which is absorbed from the skin
Radiation
-The transfer of heat energy from a warmer object
to a cooler object in the form of electromagnetic
waves (“heat waves”) which travel through space
-ex: feeling the heat from the sun on a cool day
CNS - Comparator
-primarily the hypothalamus controls temperature regulation
Thermoreceptors - Feedback
- the feedback to the CNS is from sensors through the body
- from periphery (skin)
- central (inside body)
Fever
Regulated core change in temperature
-a symptom of a disease processes
Cold fibers vs warm fibers
Warm has a higher impulse frequency between 35-50 degrees compared to cold between 20-45
thermo TRP receptors
TPRV1 - painful heat TPRV2 – painful heat TPRV3 – non-painful warmth TPRV4 – non-painful warmth TPRm8 – non-painful cool TRPA1 – painful cold
effectors - controlling elements
effect changes so that variable return back to set point
-ANS
>brown adipose tissue: non-shivering thermogenesis (adrenergic receptors beta)
>vasomotor system: thermal insulation (adrenergic delta), ex: vaso constriction or dilation
>sweat glands: sweat (ACh)
-SNS
>skeletal musculature: shivering thermogenesis (ACh)
>voluntary movement: behavioral thermogenesis (ACh)
brown adipose tissue
non-shivering thermogenesis
>transfer
energy from food into heat
>brown because highly vascolizered
>Mitochondria in eukaryotic cells utilize fuels to produce energy in the form of
ATP primarily via oxidative phosphorylation
>Uncoupling Protein in brown adipose tissue uncouples oxdiative
phosphorylation such that heat rather than ATP is generated
vasomotor system
> vasodilation: cool off
>vasocontraction: save heat to warm up
Sweat Glands
> Sweat: water goes to the surface of the skin and cools off organism
Shivering Thermogenesis
- skeletal musculature
- involuntary trembling caused by contraction or switching of muscles
- not efficient but works
- requires a lot of energy
Behavioral Thermogenesis
- voluntary movement
- think rat pups huddling together
Core Temperature
- hyperthermia: above set point/too hot
- normothermia: at set point
- hypothermia: below set point/too cold
Normothermia
temperature is at set point -autonomic response >low metabolism >high skin blood flow (keeps temperature constant) >low evaporation >low piloerection >behavioral response: don't move
Forced Hypothermia
temperature is forced below set point >high metabolism >low skin blood flow >low evaporation >high piloerection >behavioral response: move to warmer area, try to dry off if you feel into a cold river
Regulated Hypothermia (decrease in set point)
temperature is down by following set point
>low metabolism
>high skin blood flow
>high evaporation
>low piloerection
>behavioral response: move to colder area
Forced Hyperthermia
temperature is forced above set point >low metabolism >high skin blood flow >high evaporation >low piloerection >behavioral response: move to colder area
Regulated Hyperthermia (increase in set point)
ex: fever
were temperature is regulated but above set point
>high metabolism
>low skin blood flow
>low evaporation
>high piloerection
>behavioral response: move to warmer area, maybe drink something hot … etc
Human Fever
- morning temperature of 37.2 or higher
- evening temperature of 37.7 or higher
