Chapter 14 Vocabulary: The Autonomic Nervous System
1. Autonomic Nervous System - Consists of motor neurons that innervate smooth and cardiac muscle, and glands; make adjustments to ensure optimal support for body activities; operate via subconscious control; also called the involuntary nervous system or general visceral motor system. 2. Preganglionic Neuron – First neuron that resides in the brain or spinal cord. 3. Preganglionic Axon – Synapses with the second motor neuron; thin, lightly myelinated. 4. Postganglionic Neuron – Second motor neuron.
5. Autonomic Ganglion – Cell body of the postganglionic neuron is located here outside the CNS. 6. Postganglionic Axon – Extends to the effector organ; nonmyelinated. 7. Acetylcholine (ACh) – All somatic motor neurons release this at their synapses with skeletal muscle fibers.; effects always stimulatory; preganglionic fibers release this as well. 8. Nonepinephrine (NE) – Autonomic postganglionic fibers release this by sympathetic fibers. 9. Dual Innervation – While one division stimulates certain smooth muscles to contract or a gland to secrete, the other division inhibits that action; all visceral organs served by both divisions, but cause opposite effects. 10. Parasympathetic Division – Promotes maintenance activities and conserves body energy; directs digestion, diuresis, defecation; as in person relaxing or reading a book; blood pressure, heart rate and respiratory rates low; gastrointestinal tract activity high; pupils constricted; lenses accommodated for close vision. 11. Sympathetic Division – Mobilizes body during activity; “fight or flight system”; exercise, excitement, emergency, embarrassment; increased heart rate, dry mouth, cold sweaty skin, dilated pupils; kicks in fast; survivor mode. 12. Craniosacral Division – Long preganglionic fibers from brain stem and sacrum; extend from CNS almost to target organs; synapse with postganglionic neurons in terminal ganglia...
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