2. Aim: What are the parts of a reflex arc? I. Reflex – involuntary response to a stimulus. A. Stimulus – any change in the environment that causes a response (reaction). Ex: light, temperature, pressure. B. Response – the action or movement resulting from a stimulus.

3. C. Receptor – a specialized nerve tissue that is sensitive to a specific stimulus. 1. Receptors may be nerve endings in the skin which may be sensitive to temperature changes. 2. Receptors may be complex organs such as the eye or ear. Receptors are located in each sensory organ (eye, ear, tongue, skin, and nose)

4. D. Effector – part of the body that respond to a stimulus (muscles or glands). E. Parts of neuron

5. 1. Cyton (cell body) – contains the nucleus and decides what the impulse will do (stop or continue. 2. Dendrites – branches off the cyton that receive impulses from other neurons. 3. Axon – part of neuron that takes the impulse from the cyton towards the terminal branch.

6. 4. Terminal branch – end of the neuron which takes impulse to next neuron. II. Parts of a reflex arc A. Stimulus B. Receptor C. Sensory Neuron - carries impulses towards the spinal cord.

7. D. Synapse – microscopic gap between the terminal branch and the dendrite. E. Interneuron – small neuron that lies between a sensory neuron and a motor neuron. Found in spinal cord. F. Motor neuron – carries impulses away from the spinal cord toward the effector. G. Effector