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Homeostasis and temperature control
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Organisms respond to changes around them, and keep conditions inside the body steady.
Homeostasis
Organisms can respond to changes in their environment.
Homeostasis is keeping the internal environment constant. Examples: the body's water content and body temperature (about 37 °C).
Homeostasis is keeping the internal environment constant. Examples: the body's water content and body temperature (about 37 °C).
Coordinated responses
A stimulus is a change in the environment.
A receptor detects the stimulus.
An effector (a muscle or a gland) produces a response.
The nervous system or hormones coordinate the response between receptor and effector.
A receptor detects the stimulus.
An effector (a muscle or a gland) produces a response.
The nervous system or hormones coordinate the response between receptor and effector.
How the skin controls temperature
Too hot: sweat glands release sweat; as it evaporates it removes heat. Arterioles supplying the skin capillaries widen (vasodilation), so more blood flows near the surface and more heat is lost by radiation.
Too cold: less sweat. Arterioles supplying the skin capillaries narrow (vasoconstriction), so less blood flows near the surface and less heat is lost. Shivering also releases heat.
Too cold: less sweat. Arterioles supplying the skin capillaries narrow (vasoconstriction), so less blood flows near the surface and less heat is lost. Shivering also releases heat.
Explain how vasodilation helps cool the body.
- Arterioles supplying the skin capillaries widen.
- More warm blood flows close to the skin surface.
- More heat is lost from the skin to the surroundings.
Answer: More blood flows near the surface, so more heat is lost by radiation.
Homeostasis keeps the internal environment constant, such as water content and temperature. Stimulus, receptor, coordination, effector. When too hot: sweating and vasodilation. When too cold: vasoconstriction and shivering.
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