Mammalogy Exam 2 (Endothermy - Social Behavior)

Thermal Neutral Zone (TNZ)
range of ambient temperatures (between UCT & LCT) when little or no metabolic energy is required to regulate body temperature
amount of metabolic heat an animal needs to produce to offset heat lost to the environment
Thermal Conductance
rate of heat lost to the environment below LCT (influenced by SA:V and insulation)
Basal Metabolic Rate (BMR)
amount of energy required to maintain basic functions; amount of oxygen consumed per unit time at standard temperature and pressure
How do endotherms cope with the heat? (extend the limits of UCT)
larger body size (thermal inertia), fur, extremities (increased size, reduction in hair, vascularity to dissipate heat), concentration of water loss, adaptive hyperthermia, countercurrent cooling, cooling behaviors (fanning, denning, nocturnal activity, etc.)
How do endotherms cope with the cold? (extend the limits of LCT)
larger body size (Bergmann's Rule), increased insulation (fur/fat), reduction/protection of extremities (Allan's Rule), non-shivering thermogenesis (brown adipose tissue), increased behavioral thermoregulation (denning, huddling), decreased BMR, regional heterothermia (vasoconstriction/countercurrent exchange), temporal hypothermia (torpor/hibernation)
Temporal Hypothermia
heterothermy; metabolic responses to extremes in temperatures that allow animals to temporarily suspend homeothermy (hibernation: cold, estivation: heat)
Examples of temporal heterothermia:
daily torpor -> seasonal torpor - (shallow hibernation -> profound hibernation)
Daily Torpor
body temperature, respiration rate, metabolic rate, and heart rate are lowered for a portion of the 24-hour cycle