Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 438

Patterns of motor activity involving the circular and longitudinal layers of smooth muscle that extend throughout the length of the gut are coordinated by plexuses of nerves within the gut wall known collectively as the enteric nervous system. Located in the submucosa (submucous plexus) and between the muscle layers (myenteric plexus), this network contains a number of neurons (about 100 million) comparable to that present in the spinal cord.¹ The intrinsic sensory neurons, interneurons, and motor neurons that comprise the enteric nervous system control basic contractile activity such as reflex responses to distension. However, these intrinsic patterns of gut motility are modulated by both extrinsic neural and humoral signals. Central modulation of gut motility occurs via extrinsic sympathetic and parasympathetic nerves, while gut sensation is conveyed to higher centres by both the vagus and spinal afferent nerves, with noxious signals transmitted predominantly via the latter. Descending pathways to the spinal cord modulate the transmission of sensory signals.