BIO202H5 Lecture Notes - Lecture 52: Brown Adipose Tissue, Torpor
STRATEGIES FOR THERMAL REGULATION IN HOMEOTHERMS
- The centre where this fine control changes (even a single
degree) is something that the hypothalamus can control
(kicks in negative feedback systems if you’re either too
warm or too cold)
- In birds, it doesn’t quite go through the hypothalamus (it’s
a bit different)
- Too hot
• As mammals, we can take advantage of evaporative
cooling (sweating)
• Vasodilating vessels close to the skin, resulting in a loss
of heat through the skin
• Dogs can do this differently bi changing the amount of
respiration/ventilation (speed of ventilation)
• Rapid ventilation (panting) increases heat loss across
the respiratory surfaces (cooling things down by
convection and water evaporation of respiratory
surfaces through the tongue)
• for birds, they have another version of counter current
exchange in their feet
• they can have their feet in a cooler environment, and
this coolness of the environment will be exchanged
through the body with blood (the venus system)
- Too cold
• In some mammals, brown adipose tissue can be used
to heat up the body (babies usually have more of this)
• This fat can be used to generate heat
