Motor neuron provides nerve impulse that leaves gray matter of spinal cord via motor neuron's axon in ventral root and stimulates effector. Autonomic System Serves Internal Organs a. Part of PNS that controls internal organs automatically and subconsciously. Innervates all internal organs. Uses two motor neurons and one ganglion for each impulse. First of two neurons has cell body within CNS and a preganglionic fiber.
Second neuron has cell body within ganglion and a postganglionic fiber.
Relaxed State a. Cell bodies of preganglionic nerve fibers arise from craniosacral part of spinal cord and have a long axon that terminates in ganglia near or within the organ. The post-ganglionic fiber is short and releases acetylcholine. Brain and spinal cord are wrapped in three membranes, called meninges , that are filled with cerebrospinal fluid that cushions and protects. Cerebrospinal fluid is also found within the central canal of spinal cord and ventricles of brain. Neuroglial Cells Are Versatile a.