Thermoregulation

Annotations:

• Rectal/Oral Temperatures will not always directly reflect core body temperature (consider on v. cold days)

1. Air sacs

   Annotations:

   • Gular flutter: birds equivalent of panting

Annotations:

• Range of temperature in which a homeotherm can regulate its body temperature by adjusting heat loss at negligible energy cost

1. Minimal metabolic rate and energy expenditure
2. Most production processes are most efficient
3. Animal is thermally comfortable
4. Critical temps

1. Metabolism

   Annotations:

   • Heat produced from oxidative metabolism of protein, fat and carbohydrates. Varies with; feed intake, muscular activity, thermal environment and size.
   1. Body Size
      1. Bigger
         1. Lower metabolic rates
         2. Stable core body temperatures
         3. Heat loss becomes a problem
         4. Migration
         5. Low SA:V
2. Muscle Contraction
   1. Shivering
   2. Exercise
3. Non-Shivering Thermogenesis

   Annotations:

   • From metabolism of fats.
4. Environment

1. Non-evaporative heat loss to environment
   1. Convection
   2. Conduction
   3. Radiation
2. Evaporative heat loss from body surface and respiratory system

1. Physical
   1. Weather

      Annotations:

      • temperature/air speed/rain and snow
   2. Size/Shape

      Annotations:

      • Warmer climate; - Thinner limbs - Shorter coat Colder climate; - Thicker limbs - Longer coat
   3. Internal Insulation

      Annotations:

      • Fat/blubber
   4. Peripheral blood flow
   5. Colour
2. Behavioural

   Annotations:

   • - burrowing - sunbathing
   1. Too hot?
      1. Avoid sun

         Annotations:

         • seek shade/burrow
      2. Increase evaporative heat loss

         Annotations:

         • Wallow/spray/lick fur
      3. Increase non-evaporative heat loss

         Annotations:

         • Postural changes
   2. Too cold?
      1. Reduce sensible heat loss
      2. Shelter from wind and rain
      3. "Freeze" to avoid water penetration
      4. Huddle
      5. Postural changes

Annotations:

• reset hypothalamus