Lecture 3 Autonomic Nervous

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Lecture 3

Autonomic Nervous


Chapter 20 Autonomic Nervous System

  • Central Nervous System (CNS) - Brain and spinal cord

  • Peripheral Nervous System (PNS) - Located outside the brain & spinal cord

* Autonomic Nervous System (ANS) & the somatic

  • The PNS receives stimuli from the CNS & initiates responses to the stimuli after it’s interpreted by the brain

Autonomic Nervous System

  • ANS acts on smooth muscles & glands

- Controls & regulation of the heart, respiratory. system, GI tract, bladder, eyes & glands

- Involuntary - person has little or no control

  • Somatic - voluntary - person has control (skeletal muscle)


  • ANS has 2 sets of neurons:

1. Afferent (sensory) - sends impulses to the CNS for interpretation

2. Efferent - receives impulses (info.) from the brain & transmits from the spinal cord to the effector organ cells

- 2 branches - sympathetic & parasympathetic nervous system

Figure 20-2.
Sympathetic and Parasympathetic Effects on Body Tissues

ANS - Sympathetic nervous system (Adrenergic)

  • Sympathetic Nervous System (adrenergic) Norepinephrine = neurotransmitter

- Drugs that mimic = adrenergic drugs, sympathomimetics, or adrenomemetics

* Adrenergic agonists - Drugs initiate a response

- Drugs that block = adrenergic blockers, sympatholytics or adrenolytics

* Adrenergic antagonists - prevent a response


  • 4 types of adrenergic receptor organ cells:

1. Alpha-1 = vasoconstriction of blood vessels

inc. blood return to heart, inc. circulation, inc. BP

2. Alpha-2 = inhibits release of norepinephrine

dec. in vasoconstriction, dec. BP

3. Beta-1 = inc. in heart rate & force on contraction

4. Beta-2 = relaxation of smooth muscle in bronchi, uterus, peripheral blood vessels

Dopaminergic = dilate vessels, inc. in blood flow - only dopamine activates this receptor

ANS - Parasympathetic Nervous System (Cholinergic)

  • Parasympathetic or Cholinergic Nervous System

Acetylcholine = neurotransmitter

- Drugs that mimic = cholinergic drugs, parasympathomimetics

Cholinergic agonists - initiates a response

- Drugs that block = anticholinergic, parasympatholytics

Cholinergic antagonists - prevents a response


  • Sympathomimetic



From adrenergic fiber

Inc. heart rate

Pupil dilation

Adrenergic (sympathomimetic) agents

Fight or Flight

  • Parasymathomimetic



From cholinergic fibers

Dec. heart rate

pupil constriction

Cholinergic (parasympathomimetic agents)

Chapter 21: Adrenergics and Adrenergic Blockers

  • Drugs that Stimulate the sympathetic Nervous System (adrenergics, adrenergic agonists, sypathomimetics, or adrenomimetics)

  • Mimic the sympathetic neruotransmitters norepinephrine and epinephrine

  • Act on one or more adrenergic receptor sites located on the cells of smooth muscles - heart, bronchioles, GI tract, bladder, eye

  • 4 main receptors (alpha-1, alpha-2, beta-1, beta-2)



  • Stimulate adrenergic receptors: 3 categories

1. Direct-acting = directly stimulates receptors

(epinephrine or norepinephrine)

2. Indirect-acting = stimulates release of norep. from terminal nerve endings (amphetamine)

3. Mixed-acting (indirect & direct) = stimulates receptor sites & release of norep. from nerve endings (Ephedrine)

Sympathomimetic Agents/ Adrenergics

  • Action - Many of the adrenergic drugs stimulate more than one of the adrenergic receptor sites (alpha & Beta)

  • Response = Inc. BP, pupil dilation, inc. HR, & bronchodilation

  • Use = Cardiac stimulation, bronchodilator, decongestant

  • Side effects = Hyperness in body


  • Albuterol - Beta-2 agonist (bronchodilation)

Use - bronchospasm, asthma, bronchitis

SE - nervousness, restlessness

CI - severe cardiac disease, HTN

  • Epinephrine - stimulates alpha & beta

Use - allergic reaction, cardiac arrest

SE - nervousness, agitation

CI - cardiac dysrhythmias

Adrenergic Agents

  • Dopamine - alpha-1 & beta-1 stimulation

Use - Hypotension, shock, inc. cardiac output, improve perfusion to vital organs

SE - N & V, headache

CI - V. Tach

Adrenergic Blockers (antagonists/sympatholytics)

  • Block alpha & beta receptor sites (nonselective)

  • direct or indirect acting on the release of norepinephrine and epinephrine

  • Use - Cardiac arrthymias (HR), HTN ( cardiac output), angina (O2 demand)

  • SE - CHF, bronchospasm, bradycardia, wheezing

Nonselective vs Selective Beta blockers

  • Nonselective have an equal inhibitory effect on B1 & B2 receptors -

- Drugs have lots of interactions due to lots of

alpha/beta receptor sites throughout body

- use with caution on clients with cardiac

failure or asthma

  • Selective B1 helpful in asthma clients

Adrenergic Blocking Agents

  • Inderal (Propranolol) - Nonselective

Use - angina, dysrhythmias, HTN, migraines

SE - Many d/t nonselective

CI - asthma, heart block > 1st degree

  • Minipress (Prazosin) - A blocker

Use - mild to mod. HTN

SE - orthostatic hypotension

  • Tenormin (Atenolol), Lopressor (Metoprolol)

B1 (cardio) selective

Use - mild to mod HTN, angina

Chapter 22: Cholinergics and Anticholinergics

  • Cholinergics stimulate the parasympathetic nervous system

  • Mimic the neurotransmitter acetylcholine

  • 2 types of cholinergic receptors

1. muscarinic - stimulates smooth muscle &

slows HR

2. nicotinic - affect skeletal muscle

  • Many = nonselective & affect both receptors

  • Some affect only the muscarinic receptors and not the nicotinic receptors

Parasympathetic Responses

Cholinergic Agents

  • Direct acting - act on the receptors to activate a tissue response

  • Indirect acting - inhibit the action of the enzyme cholinesterase (acetylcholinesterase - ACH)

  • Major uses = Stimulate bladder & GI tone, constrict pupils (miosis), neuro-

muscular transmission

Direct-acting Parasympathomimetic (cholinergic drugs)

Cholinergic Agent (Parasympathomimetics)

  • Bethanechol (Urecholine) selective to muscarinic receptors, mimic action of acetylcholine

Use - For urinary retention

* Take on an empty stomach d/t inc. peristalsis

* Alert- Never give IM or IV – circulatory collapse, hypotension, shock & cardiac arrest poss.

  • Pilocarpine (Pilocar) - Ophthalmic - direct acting

Cholinergic Blocking Agents

  • Drugs that inhibit action of acetylcholine (ACH) receptors

  • Affects the heart, resp. tract, GI tract, bladder, eye, & exocrine glands.

  • Allows the sympathetic nervous system to dominate

  • Anticholinergic & cholinergic drugs have opposite effects

  • Major responses = dec. in GI motility, dec. in salivation, dilation of pupil (mydriasis), inc. pulse rate


  • Uses: Pre-op meds,bradycardia, GI/urinary antispasmodic

  • SE: Dry mouth/mucus membranes

  • Atropine Sulfate - Inhibits ACH blocks vagal effects on SA & AV nodes inc. conduction & inc. HR

Use = Bradycardia, pre-up to dec. secretions,

peptic ulcer disease

SE = Many. Most frequent = dry mouth, blurred vision, urine retention, constipation


  • Bentyl (Dicyclomine) - Inhibits ACH on muscarinic receptors & dec. GI motility

Use - Irritable bowel syndrome

SE - constipation, urinary retention, dry mouth

  • Robinul (Glycopyrrolate) - Similar to above

Use - pre-op to dec. secretions, GI disorders

SE - Similar to above


  • Anticholinergics effect the CNS & benefit people prone to motion sickness

  • Scopolamine Patch - Classified as an antihistamine for motion sickness

- Topical skin patch behind the ear x3 days

Use = cruising on water, flying, car sickness

Other drugs = Dramamine, Bonine

SE = Dry mouth, visual disturbances d/t pupil dilation

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