THERMOREGULATION
A.) Introduction
1. Thermoregulation is the maintenance of body temperature within a range that homeostasis
2. It may involve both behavioral and physiological adaptations.
3 ways heat is gained:
A.) Mechanisms that transfer heat
4 ways heat is lost:
Endotherms
Are animals that derive body temperature from internal heat production.
Ectotherms
Are animals that derives body temperature from an external heat source.
B.) Sources of Heat
Poikilotherm (poikilo =“varied”) - body temperature approximates the ambient temperature. Not capable of controlling body temperature as ambient temperature varies. What is the adaptive advantage here?
Heterotherm (hetero = “different”) - regulates body temperature when active, but allows body temperature to fluctuate with the environment when inactive.
Homeotherm (homeo = “same”) - controls body temperature, keeping it relatively constant as ambient temperature varies.
These terms relate to whether or not the animal is capable of controlling body temperature.
Describe the advantage to temperature homeostasis from the fact that animal bodies are made mostly of water.
Body Temperature Regulation: Endotherm vs. Ectotherm
characteristics are common
among endotherms?
are commonly well
developed in endotherms?
correctly described as
“conformers”? Illustrate your answer with some examples.
Lizard Behavioral Thermoregulation
Behavioral and physiological mechanisms in Homeotherms
Leg of a bird or mammal
Flipper of a seal or whale
Heat Exchange in Appendages
Which mechanism of heat transfer is operating here?
Cross-section:
Control of Conductance by
Regional Heterothermy
Cold-climate homeotherms can allow their appendages to cool to reduce heat loss.
Countercurrent heat exchange occurs between warm out-flowing blood in a central artery and cold in-flowing blood in surrounding veins.
Integumentary System in Thermoregulation
Organs of thermoregulation in the skin:
Why are there both cold and hot thermoreceptors in the body?
What organ serves as the control center to regulate these organs?
Temperature Homeostasis in Humans
Temperature Acclimatization
The Fluid Cell Membrane
How does the behavior of the cell membrane change with temperature?
How does the chemical make-up influence this behavior?
Wood frog, Rana sylvatica�(glucose acts as a cryoprotectant)
Wood frog in summer
Wood frog, frozen
The “winter” frog is in cardiac arrest, & has 65% of its body water frozen.
If ECF water freezes, what would happen to ICF water?
Heat-shock proteins protect and chaperone other proteins
What cell function may be faulty in these disease processes?
I love old people.. so cute! Watch and listen to this CAREFULLY. It should make you feel smart. He makes connections to MANY things you learned this year!!!
Learning Objectives
You should be able to answer these questions by Wednesday 3/25