A reflex arc is the neural pathway that controls a reflex action. It allows the body to respond to stimuli automatically, without conscious thought. Reflex arcs involve the following components:

1. Receptor: Detects the stimulus (e.g., pain or stretch).
2. Sensory Neuron: Carries the signal from the receptor to the spinal cord or brainstem.
3. Integration Center: Processes the signal, often in the spinal cord, without involving the brain for quick response.
4. Motor Neuron: Sends the response signal from the integration center to the effector organ.
5. Effector: The muscle or gland that responds by contracting or secreting, respectively.

Reflexes help protect the body by allowing rapid responses to potentially harmful stimuli. Examples include the knee-jerk reflex and the withdrawal reflex from touching something hot.