The Autonomic Nervous System (Ch 13)
Two Major Divisions of the
Nervous System
 Central Nervous System (CNS)
 Brain and spinal cord
 Peripheral Nervous System
 all nervous tissue outside the CNS, including sensory and
motor neurons
Basic Functions of the
Nervous System
 Recognizing changes in
 Internal environment
 External environment
 Processing and integrating environmental changes
 Reacting to environmental changes by producing
and action or response
Figure 13.1
Functional divisions of the peripheral nervous system.
Divisions of the Peripheral
Nervous System
 Somatic nervous system
 Voluntary control over skeletal muscles
 Autonomic nervous system
 Involuntary control over smooth and cardiac muscle and
glands
Autonomic Nervous System:
Sympathetic Nervous System
 Activated under stress
 Fight-or-flight response
 Ready the body for an immediate response to a
potential threat
Autonomic Nervous System:
Parasympathetic Nervous System
 Activated under nonstressful conditions
 Rest-and-digest response
 Digestive processes promoted, heart rate and blood
pressure decline
Autonomic Nervous System: Sympathetic and
Parasympathetic Divisions
 Branches produce mostly opposite effects
 Homeostasis – proper balance of the two branches
 achieved by changing one or both branches
 Branches do not always produce opposite effects
Figure 13.2 Effects of the sympathetic and parasympathetic nervous systems. Source: Biology Guide to the Natural
World, 2nd ed (p. 558) by David Krogh, 2002 Upper Saddle River, NJ, Prentice Hall. Reprinted by permission.
Synaptic Transmission
 Synapse – juncture of neurons
 Connection of two neurons outside CNS –
ganglionic synapse


Preganglionic neuron
Postganglionic neuron
 Many drugs affect autonomic function by altering
neurotransmitter activity at the second synapse
Five Mechanisms by Which Drugs Can
Affect Synaptic Transmission
 1. Affect the synthesis of the neurotransmitter in the




presynaptic nerve
2. Prevent storage of the neurotransmitter in vesicles
within the presynaptic nerve
3. Influence release of the neurotransmitter from the
presynaptic nerve
4. Prevent the normal destruction or reuptake of the
neurotransmitter
5. Bind to the receptor site on the postsynaptic target
tissue
Drugs Not Given to Correct Autonomic Nervous
System
 System is relatively free of disease
 Drugs used to stimulate or inhibit target organs of
the autonomic nervous system
Figure 13.3 Basic structure of the autonomic pathway.
Figure 13.4 Receptors in the autonomic nervous system: (a) sympathetic division; (b) parasympathetic division
Primary Neurotransmitters of Autonomic
Nervous System
 Norepinephrine (NE)
 Acetylcholine (Ach)
Norepinephrine
 Released by most postganglionic nerves
 Class of agents called natural catecholamines, all
involved in neurotransmission
 Adrenergic receptors - receptors at the ends of
postganglionic sympathetic neurons
Two Types of Adrenergic Receptors
 Alpha-receptors and Beta-receptors
 Hugely important to pharmacology
 Drugs are selective and activate only one type of
adrenergic receptor, whereas others affect all
receptor subtypes
Alpha1-adrenergic Receptors
 In all sympathetic target organs except heart
 Response
 Constriction of blood vessels
 Dilation of pupils
Alpha2-adrenergic Receptors
 At presynaptic adrenergic neuron terminals
 Activation inhibits release of norepinephrine
Beta1-adrenergic Receptors
 In heart and kidneys
 Response
 Activation increases heart rate and force of contraction of
heart.
 Increases release of renin
Beta2-adrenergic Receptors
 In all sympathetic target organs except the heart
 Inhibit smooth muscle
Prototype Drug: Phenylephrine (Neo-Synephrine)
Prototype Drug: Phenylephrine (Neo-Synephrine)
Norepinephrine (NE) is synthesized
 In the nerve terminal
 Requires the amino acids phenylalanine and
tyrosine
 Conversion of dopamine to norepinephrine
 NE in nerve terminal may be returned to vesicles
for future use, or destroyed enzymatically by
monoamine oxidase
Adrenal Medulla
 Anatomic and physiologic arrangement much
different from rest of sympathetic branch
Other types of adrenergic receptors
 Dopamine serves a larger role as a
neurotransmitter
Acetylcholine
 Released by cholinergic nerves
 Two types cholinergic receptors
 Muscarinic receptors
 Nicotinic receptors
Nicotinic Receptors
 In sympathetic and parasympathetic divisions at
the ganglionic synapse
 Response


Stimulate smooth muscle
Stimulate gland secretion
Muscarinic Receptors
 In parasympathetic target organs except the heart
 Response
Stimulate smooth muscle
 Stimulate gland secretion

 In heart: decreased heart rate and force of
contraction
Physiology of Acetylcholine
 Affords several mechanisms by which drugs may
act
 Synthesized in presynaptic nerve terminal from
choline and acetyl coenzyme A
 Ach in the synaptic cleft is rapidly destroyed by the
enzyme acetylcholinesterase (AchE)
Classification and Naming of Autonomic Drugs
 Based on four possible actions of sympathetic and
parasympathetic nervous systems
 Stimulate sympathetic nervous system

Adrenergic agents or sympathomimetics
 Inhibit sympathetic nervous system
 Adrenergic-blocking agents, adrenergic antagonists, or
sympatholytics
Classification and Naming of Autonomic Drugs
(cont'd)
 Stimulate parasympathetic nervous system
 Cholinergic agents or parasympathomimetics
 Inhibit parasympathetic nervous system
 Cholinergic-blocking agents, anticholinergics,
parasympatholytics, or muscarinic blockers
One of Four Drug Classes is Most Important to
Learn
 If the fight-or-flight actions of the
sympathomimetics are learned, the other three
groups can be deduced
 Mastering the actions and terminology of
autonomic drugs early will pay dividends later
Role of Nurse
 Monitor patient’s condition
 Provide education on drug therapy
 Note adverse effects of drug therapy
 Identify possible interactions
 Identify contraindications of drug therapy
Sympathomimetic
 Monitor vital signs, urinary and cardiac output as
appropriate
 Monitor breathing patterns
 Observe patient’s responsiveness to light
 Monitor for rhinorrhea and epistaxis
Nursing Process Focus: Patients Receiving
Adrenergic (Sympathomimetic Therapy)
Nursing Process Focus: Patients Receiving
Adrenergic (Sympathomimetic Therapy)
Nursing Process Focus: Patients Receiving
Adrenergic (Sympathomimetic Therapy)
Nursing Process Focus: Patients Receiving
Adrenergic (Sympathomimetic Therapy)
Anticholinergics
 Monitor for signs of anticholinergic crisis
 Report changes in heart rate, blood pressure, or
development of dysrhythmias
 Provide comfort measures for dry mouth
Anticholinergic (cont'd)
 Minimize exposure to heat or cold or strenuous
exercise
 Monitor intake and output
 Monitor patient for abdominal distension, and
auscultate for bowel sounds
Nursing Process Focus: Patients Receiving Anticholinergic Therapy
Nursing Process Focus: Patients Receiving Anticholinergic Therapy
Nursing Process Focus: Patients Receiving Anticholinergic Therapy
Nursing Process Focus: Patients Receiving Anticholinergic Therapy
Adrenergic Blockers
 Monitor urinary hesitancy, incomplete bladder




emptying, interrupted urinary stream
Monitor vital signs, level of consciousness, and
mood
Monitor for dizziness, drowsiness, or lightheadedness
Observe for side effects
Monitor cardiac output
Nursing Process Focus: Patients Receiving
Adrenergic-Blocker Therapy
Nursing Process Focus: Patients Receiving
Adrenergic-Blocker Therapy
Nursing Process Focus: Patients Receiving
Adrenergic-Blocker Therapy
Nursing Process Focus: Patients Receiving
Adrenergic-Blocker Therapy
Parasympathomimetics
 Monitor for adverse effects
 Monitor liver enzymes
 Calculate and monitor doses
 Assess and monitor for appropriate self-care
administration
Direct Acting
 Monitor intake and output ratio
 Monitor for blurred vision
 Monitor for orthostatic hypotension
Cholinesterase Inhibitors
 Monitor muscle strength and neuromuscular status
 Monitor ptosis, diplopia, and chewing
 Schedule medication around mealtimes
 Schedule activities to avoid fatigue
 Monitor for muscle weakness
Nursing Process Focus: Patients Receiving
Parasymptathomimetic Therapy
Nursing Process Focus: Patients Receiving
Parasymptathomimetic Therapy
Nursing Process Focus: Patients Receiving
Parasymptathomimetic Therapy
Nursing Process Focus: Patients Receiving
Parasymptathomimetic Therapy
Nursing Process Focus: Patients Receiving
Parasymptathomimetic Therapy
Adrenergic Agents (Sympathomimetics)
 Prototype drug: phenylephrine (Neo-
Synephrine)

Mechanism of action: to stimulate the sympathetic nervous
system directly/indirectly

produce many of the same responses as the anticholinergics
Adrenergic Agents (Sympathomimetics) (cont'd)
 Primary use: depends on receptors activated
 Alpha1-receptors: nasal congestion, hypotension, dilation of
pupils for eye examination
 Alpha2-receptors: hypertension
 Beta1-receptors: cardiac arrest, heart failure, shock
 Beta2-receptors: asthma and premature-labor contractions
Adrenergic Agents (Sympathomimetics) (cont'd)
 Adverse effects: tachycardia, hypertension,
dysrhythmias, CNS excitation and seizures, dry
mouth, nausea and vomiting, anorexia
Adrenergic-Blocking Agents
 Prototype drug: prazosin (Minipress)
 Mechanism of action: to inhibit the
sympathetic nervous system
 Primary use: hypertension, dysrhythmias,
angina, heart failure, benign prostatic hypertrophy,
narrow-angle glaucoma
 Adverse effects: dizziness, drowsiness,
headache, loss of energy and strength, palpitations,
dry mouth
Prototype Drug: Prazosin (Minipress)
Adrenergic-Blocking Agents
 Primary use of beta blockers is in the treatment of
hypertension
 Beta-adrenergic antagonists have several other
important therapeutic applications



angina pectoris
Migranes
Heart failure
Cholinergic Agents (Parasympathomimetic)
 Prototype drug: bethanechol (Urecholine)
 Mechanism of action: to activate
the
parasympathetic nervous system directly/indirectly,
induce rest/digest response
 Uses: glaucoma, urinary retention, myasthenia
gravis, Alzheimer’s disease
 Adverse effects: profuse salivation, sweating
increased muscle tone, urinary frequency,
bradycardia
Prototype Drug: Bethanechol (Duvoid,Urecholine)
Cholinergic Agents (Parasympathomimetic)
 Divided into two classes
 direct acting


bind to cholinergic receptors to produce the rest-and-digest
response
indirect acting

inhibit the action of AchE
 High potential for serious adverse effects
Cholinergic-Blocking Agents
 Prototype drug: atropine
(Atropair, Atropisol)
 Mechanism of action: to inhibit the
parasympathetic nervous system
 Primary use: peptic ulcers, irritable bowel
syndrome, mydriasis and cycloplegia during eye
examination, bradycardia, preanesthetic, asthma
 Adverse effects: tachycardia, CNS stimulation,
urinary retention, dry mouth, dry eyes, decreased
sweating, photophobia
Prototype Drug: Atropine (Atro-Pen, Atropair,Atropisol)
Prototype Drug: Atropine (Atro-Pen, Atropair,Atropisol)
Drugs Affecting the Autonomic Nervous System
 Assessment
 Potential nursing diagnoses
 Reason for drug
 Monitoring vital signs
 Doing complete health history
Drugs Affecting the Autonomic Nervous System
(cont'd)
 Cautions and contraindications for drug
 Allergies
 Drug history
 Possible drug interactions
 Evaluating lab findings
 Assess for therapeutics effect
 Watch for adverse effects
Drugs Affecting the Autonomic Nervous System
(cont'd)
 Nursing Diagnosis
 Knowledge deficient, related to drug therapy
 Risk for injury, related to side effect of drug therapy
 Disturbed sleep pattern
Drugs Affecting the Autonomic Nervous System
(cont'd)
 Planning
 Patient will exhibit therapeutic outcome based on specific
drug
 Patient will demonstrate an understanding of drug’s activity
 Patient will accurately describe drug side effects and
precautions
 Patient will demonstrate proper administration technique
Drugs Affecting the Autonomic Nervous System
(cont'd)
 Implementation
 Administration of drug
 Observing for adverse effects
 Patient education/discharge planning
 Providing additional information as needed to encourage
compliance
 Doing home-health visits
Drugs Affecting the Autonomic Nervous System
(cont'd)
 Evaluation
 Evaluating effectiveness of drug therapy
 Confirming that patient goals and expected outcomes have
been met
NCLEX-RN Review
Question 1
1. Following administration of an adrenergic
(sympathomimetic) drug, the nurse would assess for
which adverse drug effects?
1.
2.
3.
4.
Insomnia, nervousness, and hypertension
Nausea, vomiting, and hypotension
Nervousness, drowsiness, and dyspnea
Bronchial dilation, hypotension, and
bradycardia
NCLEX-RN Review
Question 1 – Rationale
Rationale: Adrenergic agonists stimulate the
sympathetic nervous system and produce symptoms
of the fight-or-flight response. Nausea, vomiting,
nervousness, bronchial dilation, and hypertension
are potential adverse reactions related to the use of
adrenergic agonists. Hypotension is a potential
adverse reaction related to the use of adrenergic
antagonists.
NCLEX-RN Review
Question 2
2. Adrenergic-blocking (antagonist) drugs may
include all of the following adverse reactions except:
1.
2.
3.
4.
Bronchodilation
Tachycardia
Edema
Heart failure
NCLEX-RN Review
Question 2 – Rationale
Rationale: Potential adverse reactions associated
with the use of adrenergic antagonists include
tachycardia, edema, and heart failure.
Bronchodilation is associated with the use of
adrenergic agonists.
Cognitive Level: Analysis
Nursing Process: Assessment
Patient Need: Physiological Integrity
NCLEX-RN Review
Question 3
3. Elderly patients taking bethanechol (Urecholine)
need to be assessed more frequently because of
which of the following side effects?
1.
2.
3.
4.
Diaphoresis
Hypertension
Dizziness
Urinary retention
NCLEX-RN Review
Question 3 – Rationale
Rationale: The nurse should monitor elderly patients for
episodes of dizziness caused by CNS stimulation from the
parasympathomimetic. Diaphoresis and dizziness are
potential side effects related to the use of bethanechol.
Bethanechol is used to treat nonobstructive urinary
retention.
Cognitive Level: Application
Nursing Process: Implementation
Patient Need: Physiological Integrity
NCLEX-RN Review
Question 4
4. The patient taking benztropine (Cogentin) should
be assessed for:
1.
2.
3.
4.
Heartburn
Constipation
Hypothermia
Increased gastric motility
NCLEX-RN Review
Question 4 – Rationale
Rationale: Anticholinergic medications slow
intestinal motility; therefore, constipation is a
potential side effect. Heartburn and hypothermia are
not associated with the use of benztropine.
Cognitive Level: Application
Nursing Process: Assessment
Patient Need: Physiological Integrity
NCLEX-RN Review
Question 5
5. The patient taking tacrine (Cognex) should be
observant for which of the following adverse effects
that may signal a possible overdose has occurred?
1.
2.
3.
4.
Excessive sweating, salivation, and drooling
Extreme constipation
Hypertension and tachycardia
Excessively dry eyes and reddened sclera
NCLEX-RN Review
Question 5 – Rationale
Rationale: Overdosage of parasympathomimetics
(cholinesterase inhibitors) may produce excessive
sweating, drooling, dyspnea, or excessive fatigue.
These symptoms should be promptly reported.
Cognitive Level: Comprehension
Nursing Process: Assessment
Patient Need: Physiological Integrity