You probably know that if one were to lightly strike a bent knee in a certain place, the leg will jerk, trying to straighten out. This reflex movement (absolute reflex) arises in the following fashion. The spinal chord is informed of a mechanical impact via a sensory neuron. At the synapse (the locus where two neurons meet) this impulse is transferred to a neuron that is responsible for body movement (motor neuron). This neuron makes the muscle contract and the leg to come straight.
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