Reflex Action

• Most reflex arcs are made up of a sensory neuron, an interneuron and a motor neuron.
• Common reflex action: pulling a hand away from a hot object.
• Reflex arcs allow fast responses to protect the body from damage.

Steps in the Reflex Action

1. Receptors in the fingers are stimulated by a hot object.
2. An impulse is carried to the spinal cord by a sensory neuron.

3. An interneuron carries the impulse across the spinal cord to a motor neuron. (At the same time, another neuron sends the message to the brain.)
4. Motor neurons carries the impulse straight out of the spine to the effector, causing the hand to pull back from the heat source.
5. As the hand withdraws, the impulse reaches the brain, making the person aware of what happened.