<prompt> Substance P is increased is response pain in periphery by which of the following?Mast cellsEndotheliumPlasmaNerve terminals  <response>: Ans. d Nerve terminalsRef: Ganong, 25th edp.141Substance PLocation- primary afferent neurons in the spinal cord, nigrostriatal system, hypothalamusResponsible for axon reflex, peristalsis, pain transmissionReceptors- neurokinin receptors NK1 -NK3 