Chapter 9

The Autonomic Nervous System

A. Overview ____________________ (ANS) manages our

physiologyBy 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

1st neuron (= ___________) has cell body in brain or spinal cord

Fig 9.1

_______________ axon extends from autonomic ganglion to target tissue

C. Divisions of the ANS1. 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 9.3

2. ____________: 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 stimulationStimulated 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