KP222 Lecture Notes - Lecture 12: Sympathetic Ganglion, Preganglionic Nerve Fibers, Postganglionic Nerve Fibers
10 Feb 2019
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Autonomic brancehes: one is excitatory, other is inhibitory. Ie. e ector organ=heart: sympathetic increase hr, parasympathetic decrease hr. Exceptions: sweat glands, smooth muscle in blood vessels. Average: on preganglionic synapses with 8-9 postganglionic neutrons: each pst neuron can innervate a di erent target. How do sympathetic and parasympathetic branches di er so similar: 1. Pathways point of origin within cns: 2. Sympathetic ganglia: most originate in spinal cord, run down vertebrae. Parasympathetic ganglia: most originate in brain stem, some originate near end of spinal cord (sacral) Sns: originate in thoracic and lumbar regions of sc, most ganglia lie close to the sc, short preganglionic, long post ganglionic, stimulates tissue metabolism and alertness. Pns: originate in brain stem and leave via cranial nerves, most ganglia lie close to target tissue, long preganglionic, short postganglionic, stimulates digestion and lowers hr. Parasympathetic innervation goes primarily to the heard, neck and internal organs. Sensory information: internal organs to brain.
