The Tendon Reflex: This reflex operates as a feedback mechanism to control muscle tension by causing muscle relaxation before muscle force becomes so great that tendons might be torn. This reflex can override the stretch reflex if necessary (making you drop a heavy weight). This reflex is also ipsilateral , but polysynaptic . Sensory receptors for this reflex are called Golgi Tendon Organs (GTOs) which are located in the tendon near the muscular attachment. In contrast to muscle spindles which detect changes in muscle length, GTOs detect and respond to changes in muscle tension that are caused by passive stretch or muscular contraction. The Flexor Reflex: Another polysynaptic reflex involves response to a painful stimulus such as stepping on a tack. In response to a painful stimulus, you immediately withdraw your leg. Thus, this response is called the Flexor Reflex or the Withdrawal Reflex. This reflex is ipsilateral . This reflex is classified as an Intersegmental Reflex Arc (since contracting the entire leg involves more than one muscle group). In this type of arc, one sensory neuron can ascend and descend in the spinal cord and activate interneurons in several segments of the spinal cord. A single sensory neuron can activate several motor neurons and therefore stimulating more than one effector. In contrast, the monosynaptic stretch reflex involves muscles receiving input from only one spinal segment. The Crossed Extensor Reflex: If you step on a tack and quickly withdraw your leg, you may lose you balance. The Crossed Extensor Reflex helps you keep you balance. Unlike the flexor reflex, the crossed extensor reflex is a polysynaptic Contralateral Reflex Arc (sensory impulses enter one side of the cord and motor impulses exit on the opposite side of the cord).
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