Homeostasis Flashcards
What is homeostasis?
The maintenance of a constant internal environment.
What does homeostasis enable organisms to do?
Enables organisms to function in a wide variety of environmental conditions. Bodily functions continue, despite the changes in the environment.
What depends on temperature?
Metabolism depends on temperature. Metabolism will slow down or even stop in living organisms if the temperature of the cells is not maintained at a certain level.
What is metabolism
The sum of all chemical reactions in a living organism.
What does a plant do when it is too hot?
It may increase transpiration to cool itself.
What is transpiration?
Transpiration is the rpocess of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.
What are endotherms?
Endotherms have a constant internal temperature depite external conditions.
What are some examples of endothermic organisms?
Dog, cat, human, etc.
What were endotherms previously called?
Warm blooded.
What are ectotherms?
Ectotherms do not have a constant internal temperature and rely on their environment for heat.
What are some examples of ectothermic organisms?
Insects, spiders, frogs and reptiles.
In animals, what are the main organs that control homeostasis?
The brian, liver, kidneys, lungs and skin.
What is the internal body temperature that mammals try to maintain?
37C.
What is the internal body temperature that birds try to maintain?
40C.
What is the main source of heat in endotherms?
Metabolism within the internal oragns, such as the liver and brain.
What hormone is metabolism controlled by?
Thyroxine.
What is an example of how an ectotherm can control their body temperature using the environment?
Reptiles will often rest in a sunny area to warm themselves up. Then, when they are sufficiently warm, they move to a shaded area.
Which of the two, endotherms or ectotherms, tend to be much less active in colder conditions?
Ectotherms.
Do environmental conditions have an effect on endotherms?
Yes.
How does the body cool itself down when it is too hot?
Through sweating, rapid breathing and vasodilation.
How does cooling occur?
Occurs when water evaporates from the skin during sweating (perspiration).
How does the body warm up when it is too cold?
Through shivering, goose bumps, vasoconstriction and secretion of thyroxine.
What is shivering?
Is the alternate contraction and relaxation of skeletal muscles. This generates heat.
What is piloerection?
Caused by the small muscles under the surface of the skin. They are connected to hair follicles and when contracted, they cause the hairs to rise up. Raised hairs trap a layer of air close to the skin.
