The contrasting mechanisms of temperature control in an ectothermic reptile and an endothermic mammal. Mechanisms involved in heat production, conservation and loss. The role of the hypothalamus and the autonomic nervous system in maintaining a constant body temperature in a mammal.

Ectothermic
These are animals that mostly gain heat from their surroundings.

• Sunlight/shade
• Absorbent/reflective colours

Endothermic
These are animals that mostly gain heat from metabolic processes.

• Vasoconstriction/dialation (changing the amount of blood that goes near the surface and loses heat)
• Surface area to volume ratio
• Shivering
• Hair raising/lowering (by erector muscles)
• Sweating
• Speeding/slowing metabolic rate

These responses have to be coordinated by the body.

• A change in heat in the environment is detected by thermoreceptors in the skin which send a message to the hypothalamus through the autonomic nervous system (the heat gain centre if it is too cold or the heat loss centre if it is too hot).
• A change in core temperature is detected in the hypothalamus (again the heat gain centre if it is too cold or the heat loss centre if it is too hot).
• Which ever area is activated will coordinate a series of responses to correct the temperature