Le réflexe myotatique - SVT - Terminale

Reflexes involve different elements that make up the reflex arc. From an initial sensation (stimulus) captured by a sensory receptor, a nerve message encoded in action potentials is produced. It circulates through the sensory neurons to the nerve center (dorsal horn of the spinal cord), where the synaptic relay to the motor neuron occurs. This conducts the nerve message to the neuromuscular synapse, which involves acetylcholine. The formation and subsequent propagation of an action potential in the muscle cell leads to the opening of calcium channels, which increases the cytosolic concentration of calcium ions, which originate from the sarcoplasmic reticulum in skeletal muscles. This induces muscle contraction and the motor response to the stimulus.