Final answer:
The path of a reflex arc is a neurological circuit that includes a sensory receptor, sensory neuron, integrating center, motor neuron, and effector, enabling a reflex action. It allows for rapid responses without involving the brain, as exemplified by withdrawal reflexes when stepping on something sharp.
Step-by-step explanation:
The path of a reflex arc refers to the neurological circuit involved in a reflex action, which typically includes several components: a sensory receptor, a sensory neuron, an integrating center in the central nervous system (usually the spinal cord), a motor neuron, and an effector (a muscle or gland).
When a reflex occurs, such as when you tap your knee with a reflex hammer, the sensory neuron carries an impulse from the knee to the spinal cord. There, it connects with motor neurons in an integrating center—without involving the brain. The motor neurons then conduct the impulse back to the muscles in the leg, prompting you to kick your leg. This is an example of a simple reflex arc.
In more complex reflexes, such as withdrawing your foot upon stepping on a tack, nociceptors in the foot send a signal through sensory neurons to the spinal cord, where the signal is processed by interneurons. This quickly results in motor neurons activating muscles that trigger the withdrawal of the foot, illustrating another reflex arc scenario.