Chapter 9 The Autonomic Nervous System

A. Overview  ____________________ (ANS) manages our physiology  By regulating _________________, & their smooth muscles & glands  Smooth muscle maintains resting tone in absence of nerve stimulation  Many types of smooth are ________________ & contract rhythmically without ANS input

B. Autonomic Neurons  ANS has ____________ in its ___________ pathway  1 st neuron (= ___________) has cell body in brain or spinal cord Fig 9.1  _______________ axon extends from autonomic ganglion to target tissue

C. Divisions of the ANS 1. 2 DIVISIONS-  sympathetic - ___________________________  parasympathetic- _____________________  characterized by _____________________ which cause Symp to mostly act as a unit (_______ ____________________) a. sympathetic

1. _____________: preganglionics branch to synapse with many postganglionic neurons Fig ____________: postganglionics receive synaptic input from large number of preganglionics

3. Sympathoadrenal System  The _______________, on top of kidney, appears to be a modified collateral ganglion  -modified ______________  release 85% ___________ (Epi) & 15% ______________ (Norepi) into blood in response to preganglionic stimulation  Stimulated during mass activation

3. Sympathoadrenal System continued  Epi is made by methylating Norepi Fig 9.8

 Is also called ________________ because long preganglionics originate in midbrain, medulla, pons, & S2 - S4  Synapse on postganglionic in _________________ located next to or within target organ  Postganglionic has short axon that innervates target b. parasympathetic __________ innervates heart, lungs, esophagus, stomach, pancreas, liver, small intestine, & upper half of the large intestine _________________ from S2-4 innervate lower half of large intestine, rectum, urinary & reproductive systems

D. ANS Neurotransmitters  Both Symp & Parasymp preganglionics release ACh  Parasymp postganglionics also release ____  Called __________ synapses  Most Symp postganglionics release ________  (noradenaline)  Called ___________ synapses Fig 9.7 para. Symp. para.

1. Adrenergic Stimulation  Causes both _________ & _________ depending on tissue  Because of different subtypes of receptors for same NT  2 major subtypes are  &  _____________ receptors  Each has own subtypes:  1,  2 &  1,  2

1. Adrenergic Stimulation  useful drugs affect ANS receptors  _________ promote NT actions  __________ inhibit NT actions Fig 9.10

2. Cholinergic Stimulation  ACh is used at all motor neuron synapses on skeletal muscle, all __________, & Parasymp postganglionics  Cholinergic receptors have 2 subtypes:  _____________ which is stimulated by nicotine;  blocked by ___________  ________________which is stimulated by muscarine (from poisonous mushrooms);  blocked by ________________

Fig 9.11

E. Other ANS NTs  Some ___________ are do not use _____ or ___  Called nonadrenergic, noncholinergic fibers  Appear to use ATP, VIP, or NO as NTs  NO produces smooth muscle relaxation in many tissues

F. Organs With Dual Innervation  Most visceral organs receive ______________ (supplied by both Symp & Parasymp)  2 branches are usually ______________, such as their effects on heart rate  Can be ________________ (cause similar effects) such as with salivation  Or __________________ (produce different effects that work together to cause desired effect) such as with __________________

G. Control of the ANS by Higher Brain Centers  ________ most directly controls activity of ANS  It has centers for control of cardiovascular, pulmonary, urinary, reproductive, & digestive systems  _______________ has centers for control of body temperature, hunger, & thirst; & can regulate medulla  _______________ is responsible for visceral responses that reflect ____________states  ______________ & cerebellum also influence ANS