Biomedical illustration of the path of the back pain and its inhibition at the level of the neurons of the spinal cord. The red arrow indicates the path of the pain that directs towards the brain. The blue arrow indicates the path of pain inhibition due to the secretion of endorphin by the hypothalamus and pituitary gland. The presynaptic neuron releases the neurotransmitters of the pain via synaptic vesicles. These neurotransmitters are released in the synaptic cleft and fix on the receptors of the synapse of the postsynaptic neuron. To fight against the pain the neuron of the inhibition will secrete endorphin (blue balls)). The endorphin fixes on the membrane receptors of the postsynaptic neuron instead of the neurotransmitters of the pain. The information of the pain is not transmitted.