Thermoregulation in Cold environments Flashcards
Define heat transfer.
Heat is trnasferred from a warmer object to a cooler object until the objects are the same temperature.
List 4 physiological adaptations to a cold environment.
- Vasoconstriction.
- Increased metabolic rate.
- Decreased metabolic rate (Torpor)
- Shivering.
Describe vasoconstriction.
Nerve impulses can stimulate the smooth muscle of blood vessel walls to contract causing arterioles to contract. This leads to reduced blood flow to the skin and reduces the loss of heat by radiation and convention. Blood remains below the insulating fat layer.
Describe increased metabolic rate.
Increased secretion of adrenaline and thyroxine which increases metabolic rate. Heat is a by product.
Describe decreased metabolic rate (Torpor).
A major adaption that enables animals to save energy when food is scarce and temperatures are extreme. Animals may hibernate. During hibernation, the metabolic rate falls to a level to sustain life. There is a reduction in body temperature. Diurination refers to a small reduction in metabolic rate and body temperature.
Describe shivering.
Is a reflex generated that involves the involuntary contraction and relaxation of muscles to generate heat and regulate body temperatures. It requires energy from metabolism and heat is a by-product.
List 4 structural adaptations to cold environments.
- Piloerection.
- Small SA:VOL ratio.
- Insulating fat.
- Insulating fur/feathers.
Describe piloerection.
An involuntary action of hairs raising to trap air close to the skin. This creates effective insulation and reduces heat loss by convection.
Describe small SA:VOL ratio.
Spherical shapes have the smallest SA:VOL ratio. Organsism that live in colder environments tend to have rounded and stocky body’s with small extremities. A reduced SA:VOL ration means there is a reduced area for heat transfer.
Describe insulating fat.
Blubber is a good insulator but a poor conductor of heat. It can prevent the conduction of heat from core to skin. It allows skin to be cooler reducing the heat gradient between it and water. Blubber has little blood flow as it has a low oxygen requirement.
Describe insulating fur/feathers.
thick fur traps a layer of air close to the body. Air is a poor conductor but a good insulator. It can stop air flow close to the body and so reduces heat loss by convection.
List 4 behavioural adaptations to a cold environment.
- Huddling/clusters.
- Staying in burrows.
- Basking in the sun.
- Migration.
Describe huddling.
Animals may huddle together and so this effectively reduces the surface area of the individual exposesed to cool air. Individuals share time outside of the group. Even being on the outside is better.
Describe staying in burrows.
Creates a warmer microclimate and reduces the temperature gradient. Animals will increase the temperature of the burrow as the radiate heat from their body.
Describe basking in the sun.
Animals would absorb heat energy from the sun through radiation.
