Final answer:
The three key features of a reflex arc are the sensory receptor, the integration center, and the motor neuron, which together allow for rapid, involuntary responses to stimuli.
Step-by-step explanation:
The three key features of a reflex arc are:
Sensory receptor: This component detects the stimulus (such as pain or temperature), initiating the reflex action.
Integration center: Typically located in the spinal cord, it comprises one or more synapses. It acts as a processing center where the sensory neuron interfaces with a motor neuron.
Motor neuron: This component transmits the signal from the integration center to the effector, such as a muscle, which carries out the reflex action (e.g., withdrawing a hand from a hot object).
A reflex arc enables involuntary actions, which can be very beneficial to an organism, providing rapid responses to stimuli without direct involvement from the brain, thus saving crucial time in situations that require immediate action.