Stimulus and Response. Year 9 Science . Any change in an organism’s environment that causes the organism to react. (“cause”) Stimuli (singular) can be: External Internal. Stimulus. Response. How an organism reacts to a stimulus (“effect”) Responses can be: Voluntary Involuntary.
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Stimulus and Response
Year 9 Science
Touch a hot surface...
Hear a loud bang...
Raise your body temp...
...pull back your hand
...start to sweat
...put on something warm
Some responses are instinctual (we are born with them)
Other responses can be learned.
Some responses happen without any thought whatsoever.
These are known as involuntary responses.
Can you think of others?
A reflex arc is a fast response that occurs automatically, without any thought. These are the fastest responses in your body
For example, when you touch something hot, you pull your hand away before you “think” about it being hot.
The stimulus (heat) is relayed along the sensory neuron through the spinal cord to the effector which makes you move your hand.
Homeostasis: the maintenance of a stable internal environment in spite of external or internal environmental changes.
The body is constantly working to maintain homeostasis inside us by coordination of our body systems.
Blood Glucose Maintenance