Download The Reflex Arc

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