Reflexes Uncovered A reflex arc consists of five essential components – a receptor, sensory neuron, integration center, motor neuron, and an effector. A reflex arc is an automatic response that protects a person from injury by allowing for immediate withdrawal from harmful stimuli. This response is present in situations that call for immediate action, such as when a person steps on a sharp object; instead of sending sensory information to the brain to be processed, a reflex arc rapidly processes and produces the protective response without having to wait for directions from the brain. The process begins when a receptor, which can be specialized cells or the dendrites of a sensory neuron, is activated by the arrival of a stimulus, and ends with the response by an effector. When a person steps on a sharp object, such as a tack, a reflex arc …show more content…
The reflex process begins when the tack, or stimulus, makes contact with the integument on the bottom of the foot; this is the arrival of a stimulus. The stimulus’ pathway starts at the epidermis, where it will penetrate all five layers, from the outermost stratum corneum, it travels through the stratum lucidum, stratum granulosum, and stratum spinosum, all the way to the innermost stratum basale. From there, it will continue into the dermis, where there is an extensive network of nerve endings and nerve fibers throughout the two layers of the dermis. The papillary layer contains Meissner’s corpuscles, touch receptors that are sensitive to light touch, which would be able to sense the feeling of the tack making contact with the epidermis. Within the reticular layer are Pacinian corpuscles, touch receptors that can detect deep pressure and vibration, such as the pressure of the tack against the foot. However, when the mechanical pressure of the tack against the tissue of the foot becomes so strong that it causes damage, pain receptors known as nociceptors take over. Once the tack