Lecture 5 – Temperature Regluation, Thirst
body wants to maintain this balance (not too hot not too cold, etc)
brain contributes quite a bit to this process
Motivation:Any process that activates and directs behaviour towards this homeostatic level.
If animal MOVES TOWARD consuming food = motivation
Not just eating the food. You don't only have to see the animal eating food but also
moving in that direction to get the food.
➢ Body Temperature
Set point (ideal equilibrium/balance)
Nervous system controls temperature of the body
Spinal Cord, Brain Stem, and Hypothalamus = mutliple thermostats
Spinal Cord – takes a few degrees of change to step in
• below 35 and over 39
Brain stem – below 36 or above 38
Hypothalamus – has the narrowest zone
• 36.5 – 37.5 – anything out if this range will cause it to step in and do
• This range may be narrower in women going through menopause and this
could be responsible for hot flashes.
➢ Animals & Temperature
maintain a constant temperature
We have several automatic internal responses
What happens if the temperature drops? What do we do behaviourally?
• We shiver, blood vessels constrict, curl up, thyroid hormone increase will increase
metabolic activity which will thus increase heat
• Warmer temps: Perspire, dogs lick themselves,
Problems: Raynaud's disease (white fingers) dramatic response to changes in temp?
Deviations in Human Core Temperature:
• controlled increase in the temperature
• Heat Stroke (Hyperthemia)
• Core temperature increases
• Elderly & the very young
• Extremely cold env'ts
• Your periphery wud suffer before your central nervous system (your brain wud
still be most protected but it cant last for that long)
Ectotherms use external env't to change body temperature
Dependent on behavioural responses
Develop fur to keep them warm, change colour of fur
Surface to volume ratio affects temperature
the higher this ratio is (surface area to its volume, harder it is to maintain core