BIOB34H3 Lecture 10: Thermal Relations
23 Oct 2016
School
Department
Course
Professor
BIOB34
LEC 10 - Thermal Relations
October 6, 2016
RECAP
● Animals use chem energy to make ATP via enzymes
○ All the enzyme reactions are temperature dependent
● Use energy in ATP to decrease entropy
Objectives
● Distinguish b/w homeothermy vs. poikilothermy and thermoregulation vs. non-
thermoregulation
● Explain how heat is transferred b/w an animal and the environment
● Understand how temp affects cellular function and survival
● Describe how poikilotherms survive extreme temps
● Describe mechanisms used by animals to thermoregulate
→ Homeotherm vs Poikilotherms
● Homeotherms→ generate heat metabolically to regulate their body temp
● poikilotherms→ regulate their body temp through behaviour
○ Example: turtle sitting out in the sun is regulating temp
○ Hibernate only because their entire body will shut down when it’s too cold
→ Endothermy
Poikilotherms / Ectotherms
Ectotherm→ the heat that you
get has to come from the
external environment
Endotherms - you can
generate enough heat
through metabolic
thermoregulation to keep
body warm
No Endothermy
Yes Endothermy
No Thermoregulation
Nonthermoregulating
poikilotherms or ectotherms
Nonthermoregulating
endotherms
Yes Thermoregulation
Thermoregulating
poikilotherms or ectotherms -
Behavioural
Thermoregulators
Thermoregulating
endotherms - Homeotherms
- You can have nonthermoregulating endotherms → animal that generates enough heat
that exceeds the environmental temp BUT doesn’t use that heat to regulate their own
body temp → WASTE OF ENERGY
find more resources at oneclass.com
find more resources at oneclass.com
→ Heterothermy
● Some animals may regulate their body temps only in certain parts of their body or at
certain times → HETEROTHERMY
○ EXAMPLE: an animal’s limbs → husky
■ It’s legs and arms are not the same temp as its core
■ Keeps core at constant 37 degrees→ a lot of catalyzed reactions
occurring in the core that need the function of enzymes = critical to
survival
■ Arms and legs can drop in temp → to save energy
● Animal has variety of resources to obtain heat and many ways it can lose heat to the
environment
○ Metabolic heat production
○ Conduction
■ Gain heat from things it’s touching
■ Lose heat as well
○ Convection
■ lose/gain heat through forced air flow
○ Radiation
■ Can lose/gain heat through radiation
■ Includes bushes, grass, and things that contact radiation
→ Conduction and Convection
● Law of conduction
○ Hconduction = k * [(Tb - Ta) / d] → measure of heat loss
■ K = thermal conductivity
■ Ta = environment temp
■ Tb = body core temp
■ If Tb > Ta → (+) heat loss
■ If Tb < Ta → (-) heat loss = heat GAIN
○ Diffusion of heat
○ When 2 objects are touching, the random kinetic energy from one object gets
transferred to the other object b/c of the fact that the mol are always moving
around
● Laws of convection
○ Hconvection = Hc (Ts - Ta)
■ Ts = body surface
○ Hc ~ square root of V / square root of D
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Animals use chem energy to make atp via enzymes. All the enzyme reactions are temperature dependent. Use energy in atp to decrease entropy. Distinguish b/w homeothermy vs. poikilothermy and thermoregulation vs. non- thermoregulation. Explain how heat is transferred b/w an animal and the environment. Understand how temp affects cellular function and survival. Describe mechanisms used by animals to thermoregulate. Homeotherms generate heat metabolically to regulate their body temp. Poikilotherms regulate their body temp through behaviour. Example: turtle sitting out in the sun is regulating temp. Hibernate only because their entire body will shut down when it"s too cold. Ectotherm the heat that you get has to come from the external environment. Endotherms - you can generate enough heat through metabolic thermoregulation to keep body warm. You can have nonthermoregulating endotherms animal that generates enough heat that exceeds the environmental temp but doesn"t use that heat to regulate their own body temp waste of energy.
