Knee Jerk Reflex Research Paper

The knee-jerk reflex is considered a stretch reflex and is often used by physicians to test how the nervous system is functioning. The knee-jerk reflex is tested by tapping the patellar tendon with the base of a rubber hammer. This results in the leg and foot extending upward in healthy individuals. The reflex is a response to the change in shape of the patellar tendon and quadriceps muscle. It does so to prevent damage to the muscle and ultimately the maintain homeostasis.

There are a series of steps that lead to the initiation of the response. The process starts with a message, known as a neural impulse, that is sent and delivered to the central nervous system. The overall pathway that the neural impulse travels is often called the reflex arc and it includes several key …show more content…
A motor unit is a motor nerve and all the fibers that it innervates. Motor units make up muscles and they are recruited based on the size principle. This means that generally smaller motor units are recruited first. These motor units have less muscle fibers when compared to the larger motor units resulting in a lower force production. Motor units are recruited based on the amount of load as well. A light load would result in a weak stimulus and would lead to the recruitment of small motor units. Again these motor units aren’t able to produce the force that larger motor units can because they innervate less fibers, but they are better with precision and fine motor control. With an increase in load, larger motor units are recruited. An increase in motor unit recruitment results in more fibers being activated and therefore increases muscular contraction so that a larger force is able to be produced. Training is a direct effect of this. Trained individuals often have improved motor recruitment. This is likely due to better retrieval of the stimulus and synchronization of motor neurons firing, which is discussed