Homeostasis - Thermoregulation Flashcards
Define homeostasis.
The maintenance of a stable internal environment in the face of external change.
Communication systems via. hormones/nervous system.
What are endotherms?
Regulate their body temperature - generating internal heat via. metabolic processes; e.g. mammals and birds.
What are ectotherms?
Unable to regulate body temperature - fluctuating with external temperature. Relying on behavioural/structural features to stay warm; e.g. reptiles and amphibians.
Outline 4 physical heat exchange processes.
Conduction - heat transfer from direct contact.
Convection - heat conducted away - low to high temperatures.
Radiation - heat transfer from non-direct contact.
Evaporation - change of liquid to vapour - heat loss only.
Endotherm: Advantages/Disadvantages.
+ Maintain body temp, high levels of aerobic metabolism, sustainable vigorous activity.
- Greater food requirements for a higher metabolic rate.
Ectotherm: Advantages/Disadvantages.
+ Less food required, more energy can be used for growth and repair.
- Can not adjust to heat differences, inactive of activity until optimal temp is reached.
Outline mechanisms for thermal regulation.
Insulation - fur, feathers, fat.
Evaporative Cooling - sweating, panting, bathing.
Shivering.
Circulation adaptations - counter current exchange, vasodilation/constriction.
Structural - large SA: Vol ratio - big ears.
Behavioural - hibernation, burrowing, huddling, nocturnal/diurnal activity.
Outline key adaptations of thermal insulation.
Piloerection of hairs/fur of animals - goosebumps; trapping a layer of warm air from leaving the organism.
Fat/blubber.
What is vasodilation/constriction?
Vasodilation - veins widen to increase blood flow - increasing heat exchange; cooling the body.
Vasoconstriction - veins tighten to limit blood flow - limiting heat exchange keeping the organism warm.
Discuss the temperature response mechanism for ectotherms.
Circulation - blood vessels lie next to one another in the extremities; heat exchanged via. conduction.
Behavioural - periods of inactivity, positioning for heat absorption, in the sun.
Structural - cells contain antifreeze (cryoprotectant) to prevent freezing.
Outline key behavioural responses to temperature.
Burrowing, huddling, hibernation, nocturnal/diurnal, sun-basking, seeking shade, swimming, migration.
What are the key differences between homeothermic and poikilothermic organisms?
Homeotherms are organisms that maintain a relatively constant temperature.
Poikiliotherms are organisms that cannot control a constant temperature, it fluctuates with the environment.
Most organisms are homeothermic endotherms/poikilothermic ectotherms.
What is a negative feedback loop?
Counteract changes of various properties from their target values, known as set points.
What is a positive feedback loop?
Amplify their initiating stimuli, in other words, they move the system away from its starting state.
