AUTONOMIC NERVOUS SYSTEM NOTES CHAPTER 14 AUTONOMIC NERVOUS SYSTEM NOTES
2 Our internal environment constantly deviates from the optimum norm so our systems need to be constantly functioning to bring these changes back to the optimum levels and maintain homeostatic balance Many systems contribute to this stability though it is primarily dependant on the Autonomic Nervous System It’s a system of motor neurons (no sensory) that innervates smooth and cardiac muscle and glands.
3 It performs all of these tasks involuntarily without any conscious thought Involuntary means smooth muscle Go back to the hypothalamus, pg.443-444 Medulla oblongata, pg 449
4 The ANS is divided into two divisions: Sympathetic & parasympathetic Sympathetic- “Fight or flight” activates when we are excited or in emergency or threatening situations Parasympathetic- “Resting or digesting” activities
5 Figure: 14.1; page 526
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10 General Anatomy In the somatic system (voluntary effectors) there is only one motor unit (dendrites, body,axon) This is true for the sensory units as well except there is no sensory part of the ANS
11 Each motor unit in the ANS consists of 2 motor neurons: 1 11 Each motor unit in the ANS consists of 2 motor neurons: 1. A Preganglionic neuron with its cell body in the CNS, its preganglionic axon synapses in an autonomic ganglion 2. A Postganglionic neuron with its cell body in an autonomic ganglion with a postganglionic axon extending to the effector
12 Figure: 14.2; page: 527
13 The arrangement of the 2 motor units and subsequently the 2 ganglions are somewhat different between the parasympathetic and the sympathetic divisions Pararsympathetic (Craniosacral) Division - Rest and digest -Preganglionic fibers (axons) come from the cranial nerves and the sacrum -The preganglionic axons go to the terminal ganglion that is located just outside the effector or inside the effector
14 Figure: 14.4; page: 529
15 Figure: 14.4; page: 529
16 Figure: 14.4; page: 529
17 Sypmpathetic (thoracolumbar) division - fight or flight More complex All preganglionic fibers (axons) arise from preganglionic neurons in spinal cord segments T1-L2 The preganglion neurons are in the lateral horns of the spinal cord gray matter The preganglionic axons all go to a sympathetic trunk ganglion which are all interconnected and aligned up in orderly fashion along the side of the spine
18 Fig. 12.31; pg. 469 ventral, dorsal, lateral
19Figure: 14.6; page: 533 sympathetic
20 Figure: 14.6; page: 533
21 Figure: 14.6; page: 533 collateral ganglion
22 More complicated – The preganglionic axons can do one of three things when they reach the chain They can synapse w/ the chain ganglia at that level The axon can ascended or descend to another trunk ganglion – This is what holds the chain together They can pass through the trunk completely and synapse with a distant collateral ganglion
23 Figure: 14.5; page: 531 same level
24 Figure: 14.5;page:531 ascending/descending
25 Figure: 14.5; page: 531 collateral ganglion