General organization of central and peripheral components of the nervous system

Transcription

1 General organization of central and peripheral components of the nervous system Today we are focusing on the ANS Part of ANS?? Life depends on the innervation of the viscera... all the rest is biological luxury. - Nauta & Feirtag From the old edition of Silverthorn, Figure 8-1 1

2 Silverthorn Figure

3 General organization and function of the Autonomic Nervous System Thoracolumbar Craniosacral 3 Revised from Silverthorn Figure 11-5

4 Just like the previous slide, but separating sympathetic and parasympathetic Widmaier Fig. 6-44; Like silverthorn

5 Innervation of tissues by both sympathetic and parasympathetic divisions The two divisions have opposite actions Issue of dual innervation Issue of integration 5

6 6

7 The autonomic nervous system is a two neuron chain from CNS to target tissue Vander Widmaier Fig. 6-46; like silverthorn 11.6

8 Organization of preganglionic and postganglionic neurons Brain ACh Terminal ganglion ACh Effector organs Cardiac muscle = Sympathetic system = Parasympathetic system = Preganglionic fiber Spinal cord ACh NE = Postganglionic fiber Craniosacral parasympathetic nerves Thoracolumbar sympathetic nerves Sympathetic ganglion chain Smooth muscle = Acetylcholine = Norepinephrine = Epinephrine = Cell body Adrenal medulla ACh Blood E,NE NE = Cell body = Axon Collateral ganglion ACh Terminal ganglion ACh Most exocrine glands and some endocrine glands [Consider this in the context of slide 6] 8

9 Sympathetic preganglionic neurons are in the intermediolateral cell column in thoracic and lumbar spinal cord Axons of preganglionic neurons exit spinal cord as part of ventral root Outside of CNS, preganglionic neurons synapse with postganglionic neurons Germann

10 6 (again)

11 In response to increased sympathetic nervous system activity Heart: beats faster and stronger Blood vessels: constrict, and therefore blood pressure goes up (no parasymp) Eyes: pupil widens and eyes pop out Respiratory tree: airways dilate Digestive tract: decreased motility and secretion (decreased digestion) Adipose tissue: increased fat breakdown (no parasymp) Liver: make more glucose available (glycogenolysis, gluconeogensis) (no parasymp) Sweat glands: increased sweating (no parasymp) Kidney: increase renin secretion (and increase sodium retention) (no parasymp) Urinary bladder: prevent voiding 10

12 * * ** * * * * * Pay particular attention to these 11

13 The autonomic nervous system is a two neuron chain from CNS to target tissue Vander Widmaier Fig (a repeat of slide 7); like Silverthorn 11.9

14 Receptor subtype does make a difference! (or maybe NE>E) What does this column actually mean? From Germann; like silverthorn table

15 Sympathetic nervous system and the adrenal medulla: Spinal cord = Acetylcholine Sympathetic preganglionic fiber = Norepinephrine = Epinephrine Adrenal medulla Sympathetic postganglionic fiber Blood Target organs Sherwood Figure

16 Pharmacology of the autonomic nervous system atropine (muscarinic receptor antagonist) hexamethonium (ganglionic nicotinic receptor antagonist) curare (neuromuscular junction nicotinic receptor antagonist) propranolol (beta-adrenergic receptor antagonist) phentolamine (alpha-adrenergic receptor antagonist) isoproterenol (beta-adrenergic receptor agonist) phenylephrine (alpha-adrenergic receptor agonist) tyramine (sympathomimetic; causes norepinphrine release) eserine = physiostigmine (blocks the breakdown of acetylcholine) 15

17 The baroreceptor reflex as an example of an autonomic reflex Regulation and integration; where and how Basal tonic activity; where does it come from Integrated control of SNS and PNS 16

18 [try to create this table on your own (like Silverthorn table 11.4 and figure 11.9] Autonomic Autonomic parasympathetic sympathetic somatic CNS site of origin # neurons in pathway Neurotransmitters Neurotransmitter receptors effects on target control 17

19 What controls the autonomic nervous system? Regionally selective Driven by brain Germann and Stanfield, Principles of Human Physiology 18

20 Pseudorabies virus (PRV) can be used to map the circuits controlling autonomic structures: 32 1 Inject PRV 19

21 PRV can be used to map the circuits controlling autonomic structures: 5 classical presympathetic regions: 2 1 RVLM RVMM Raphe A5 PVN (hypothalamus) Inject PRV

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23 Early infection Intermediate infection Late infection (PRV injection into spleen) 22

24 Spleen Kidney Early infection Intermediate infection Late infection

25 Pattern of retrograde labeling of presympathetic neurons in brain differs (a little) depending upon target Kidney: RVL > A5 > VMM Spleen: A5 > RVL > PVN Brown Fat: A5 > Raphe > RVL 24

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29 Integration of autonomic, endocrine and behavioral responses Silverthorn Figure

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