1. A reflex arc is a neural pathway consisting of neurons and their fibers that regulate a reflex - specific response to a certain stimulus.
2. The reflex arc consists of sensory neurons, motor neurons, interneurons, and their fibers - axons and dendrites.
3. The pathway of the reflex arc: receptor in the skin or other organ, afferent nerve fiber traveling from the organ to the spinal cord or the brainstem, an integrating center (a grey matter of spinal cord or brainstem containing the body of sensitive neurons), efferent nerve fibers (motor neuron fibers), effector (muscle or other target organ carrying the response) to a stimulus).
4. Knee jerk reflex is a tendon reflex that leads to a sudden kicking movement of the lower leg in response to a tap on the patellar tendon.
5. The knee jerk reflex was first noted in 1875.