BIOL 2020U Lecture Notes - Vagus Nerve, Paravertebral Ganglia, Splanchnic Nerves
Document Summary
Somatic neurons project directly to skeletal muscles and nothing else; motoneurons (cell bodies in spinal cord) terminate at motor end plates and release ach onto skeletal muscles, causing contraction. Autonomic neurons also lie in the spinal cord but do not project directly to targets; instead, the preganglionic neurons project to postganglionic neurons in ganglia, which project directly to targets. For cv: hr, contractility, contracts vsm, vascular resistance. Preganglionic neurons found in t1-l3 and project to three places: paravertebral ganglia (sympathetic chain, prevertebral ganglia (reached via long splanchnic nerves, adrenal gland chromafin cells (via splanchnic nerve) Preganglionic neurons release ach, postganglionic neurons release ne. Even at rest there is a certain amount of sympathetic tone. For cv: hr, relaxes vsm in certain tissues, vascular resistance, blood flow. Preganglionic neurons are found in brain and sacral spinal cord. Ganglia are found in or near targets. Only vagus nerve innervation is important here (particularly of the sa and av nodes)
