ESYS 101 Lecture Notes - Lecture 15: Torpor, Heart Rate, Marine Mammal
Thermoregulation
● Total thermal tolerance
○ Greater area = greater tolerance
● Internal chemical environment
○ Animals function between 0C and 40C
○ Biochemical activities are sensitive to temp
■ Enzymes have optimum temp
○ Temp constraints on animals are due to their need to maintain biochemical
stability
■ Too cold: metabolic reactions too slow to main activity and reproduction
■ Too hot: enzyme activity impaired or destroyed
● Temp and physiology
○ Increased temp increases rate of most physiological process
○ = increase in rate caused by increase in temp of 10CQ10
■ Ex. = 2 means increase in 10C causes doubling of rateQ10
● Terminology
○ Poikilothermic = variable internal temp
○ Homeothermic = constant internal temp
■ But deep sea fish live in constant temp
■ Mammals have variable body temp
● Endotherms vs. Ectotherms
○ Endotherm: internal heat sources enough to maintain body temp
■ Heat derived from oxidative activity
○ Ecotherm: external heat sources determine body temp
■ Heat derived from environment
○ Heterotherm: endothermic during activity, ectothermic at rest
■ Bats, birds
● Heat and heat exchange
○ If temp constant, heat loss= heat gain
■ Metabolic heat production = heat lost
○ How can heat be lost from body?
■ Conduction
■ Radiation
■ Evaporation
● Adaptations heat/cool
○ To keep cool:
■ Conductance (total heat flow from animal)
● Increasing circulation to skin
● Increasing exposed surface area
● Increasing evaporation
○ Sweating, panting, licking
■ In large animals
● Variable body temp reduces evaporation of water
Document Summary
Temp constraints on animals are due to their need to maintain biochemical stability. Too cold: metabolic reactions too slow to main activity and reproduction. Too hot: enzyme activity impaired or destroyed. Increased temp increases rate of most physiological process. = increase in rate caused by increase in temp of 10c. = 2 means increase in 10c causes doubling of rate. But deep sea fish live in constant temp. Endotherm : internal heat sources enough to maintain body temp. Ecotherm : external heat sources determine body temp. Heterotherm : endothermic during activity, ectothermic at rest. If temp constant, heat loss= heat gain. Variable body temp reduces evaporation of water. Deep slow breathing reduces respiratory water loss. In water, no evaporation or radiation, high conductance. For warmth, increase metabolic rate or reduce conductance. Maximize heat gain by positioning themselves by increasing surface area. Endotherms must always have energy to support high metabolic rate.
