ms nervous system

7/30/2019 MS Nervous System

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The Nervous System

Central Nervous System

Peripheral Nervous SystemSomatic Nervous System

Autonomic Nervous System

DIV IS IONS OF NERVOU S

SYSTEM

The Central Nervous

System

(CNS)Consists of the brain and spinal cord

Regulates body functions

Interprets information sent by the

peripheral nervous system (PNS ) and

then sends stimuli back to the PNS

Peripheral Nervous System

Somatic NS acts on skeletal muscles

to produce locomotion & respiration

Autonomic NS visceral system;

controls and regulates functioning of the

heart, respiratory system, digestive

system & glands

Sympathetic nervous system

Parasympathetic nervous system


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Features of Autonomic Nervous System

2 neuron system

Synaptic transmission

Synapse - space between neurons or between

neuron and its target organ

Presence of Ganglion/ganglia

Ganglia collection of nerve cell bodies outside

CNS

Comparison of SNS and PSNS

SYMPATHETIC PARASYMPATHETIC

Origin of

fibers

Thoracolumbar Craniosacral

Length of

fiber

Preganglionic: short

Postganglionic:long

Long

Short

Receptors Alpha, beta,

dopamine

Muscarinic,

Nicotinic

NT NE, EPI, dopamine Acetylcholine

Responses

General

Fight, flight, fright Rest and digest

Receptors

1. Nicotinic receptors are located on thecell bodies of all postganglionicneurons of the PSNS and SNS (&adrenal medulla)

2. Muscarinic receptors are located in allorgans regulated by the PSNS

3. Adrenergic receptors are located in allorgans regulated by SNS except sweatglands

Neurotransmitters

1. All preganglionic neurons of the PSNS andSNS release ACh as their transmitter.

2. All postganglionic neurons of the PSNSrelease ACh as their transmitter.

3. Most postganglionic neurons of the SNSrelease NE

4. EPI is the principal transmitter released by

adrenal medulla5. All motor neurons to skeletal muscles

realese ACh as their transmitter

The Sympathetic NS

Fight or flight response the bear

prepares the body for stress by

increasing metabolism, diverting blood to

larger muscles and increasing cardiacand respiratory functions

The Parasympathetic NS

Rest and digest response increases

digestion, absorption and slows

metabolism to save energy the pig

SNS vs. PNS Effects on Tissues

SNS Effects

Dilates pupils

Relaxes smooth

muscles of the GIT

Dilates bronchioles

Increases heart rate

Constrict blood

vessel

Relaxes bladder &

uterine muscle

PNS Effects

Constricts pupils

Increases peristalsis

Constricts

bronchioles &

increases secretions

Decreases heart

rate

Dilates blood

vessels

Increases salivation

Sympathetic Nervous System

Also called theadrenergic system (adrenaline)

The neurotransmitter isnorepinephrine Drugs thatmimicthe effects of norepinephrine are the

adrenergics, sympathomimeticsor ad renomim etics

Because they initiate a response they are calledadrenergicagonists

Drugs whichblock the SNS are calledsympatholyticsor adrenolytics, anti-adrenergicsand thealpha andbeta adrenergicblockers; because they b lock aresponse, they areadrenergicantagonists


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Parasympathetic Nervous System

Also called the cholinergic system

The neurotransmitter is acetylcholine

Parasympathomimetics , cholinomimetics andcholinergics stimulate the PNS

Called cholinergic agonists because theyinitiate a cholinergic response

Parasympatholytics, anticholinergics andcholinergic blocking drugs inhibit the PNS;

called cholinergic antagonists because theyblock a response

Comparison of SNS & PNS Drugs

Sympathetic

Response the bear

Agonist

Sympathomimetics

Adrenergic drugs

Antagonist

Sympatholytics

Adrenergic blockers

Parasympathetic

Response the pig

Agonist

Parasympathomimetic

Cholinergic drugs

Antagonist

Parasympatholytic

Anticholinergic drugs

Cholinergic blockers

Functions of Peripheral Adrenergic Receptor

Alpha 1 Eye Mydriasis

Arterioles Constriction

Sex organ, male EjaculationBladder neck, prostatic capsule Contraction

Alpha 2 Presynaptic nerve terminal Blocks NE release

Beta 1 Heart +Inotropic,Chronotr

opic, dromotropic

Kidney Renin release

Beta 2 Arterioles Dilation

Bronchi Dilation

Uterus Relaxation

Liver Glycogenolysis

Adrenergic Drugs: Review

Act on adrenergic receptor sites on the cells ofsmooth muscles

Adrenergic receptorsAlpha1 vasoconstriction; increases cardiac

contraction; mydriasis, bladder neck and prostaticcapsule contraction

Alpha2 inhibits norepinephrine, dilates bloodvessels; decreases GIT tone & motility

Beta1 increases rate & force of cardiac contraction;increases renal secretion of renin, increasing BP

Beta2 dilates bronchioles ; glycogenolysis;increases skeletal muscle blood flow; GIT/uterinerelaxation

Catecholamines

The chemical structures of a substance,

either endogenous or synthetic, that can

produce a sympathomimetic response

Endogenous

Dopamine, epinephrine & norepinephrine

Synthetic

isoproterenol, dobutamine

Indications of Adrenergic Drugs

Emergency drugs inotropic drugs, vasopressors

Cardiac arrest, hypotension, heart failure

Asthma, URT congestion bronchodilation,vasoconstriction

Allergies, bleeding vasoconstriction Hypoglycemia glucogenolysis

Obstetric use stops premature labor

Eye disorders causes pupil dilation

Not for patients with glaucoma

Used with local anesthetics vasoconstriction

Alpha and beta adrenergic agonists

Dobutamine

Dopamine

Ephedrine

Epinephrine

Metaraminol

Norepinephrine

Adrenergic Drug: Epinephrine

Epinephrine (Adrenaline Cl) acts indirectly bystimulating release of norepinephrine whichacts directly on adrenergic receptor sites

Can be given IV, IM, topical, inhalation or SQ

Used to fight anaphylaxis ; rapid onset of actionPotent inotropic drug ; may reduce renal

perfusionNurses must monitor vital signs carefully

and watch for rapid heart rate, dizzinessand increased blood pressure; ECGmonitoring


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Beta specific adrenergicadrenergic agonists

Albuterol

Bitolterol

Isoetharine

Isoproterenol

Salmeterol

Terbutaline

Metaproterenol

Isoproterenol HCl (Isuprel)

Bronchodilation & increase in heart rate

Can cause severe tachycardia

Often used to treat asthma

Albuterol (Proventil, Ventolin)

Produces rapid bronchodilation

Used to treat bronchospasms

SE: tachycardia, tremors, restlessness,

nervousness

Caution : taken with mono amineoxidase inhibitors (MAOI), may cause

hypertensive crisis

Alpha specific adrenergic agonists

Clonidine

Midrodrine

Phenylephrine

Clonidine (Catapres) &Methyldopa (Aldomet)

Alpha2 adrenergic drugs

Treats hypertension by regulating /

inhibiting the release of norepinephrine

May cause cardiovascular depression by

stimulating alpha2 receptors in the CNS

SE: tachycardia, palpitations,

dysrrhythmia, n/v, urinary difficulty,

tremors, dizziness

Nursing Responsibilities

Frequent VS monitoring

Check urinary output , bladder distention

Check for IV infiltration. Norepinephrine & dopaminemay cause tissue necrosis . Antidote is Phentolaminemesylate (Regitine)

Take with food to prevent N/V.

Monitor labs may increase glucose level Glycogenolysis

Read OTC labels: cold medicines, diet pills

Rebound nasal congestion may occur.

DO NOT give to nursing mothers.

Adrenergic Blockers

Blocks the effects of neurotransmitters

Alpha blockers cause a decrease in blood

pressure, orthostatic hypotensionBeta blockers decrease heart rate and force of

cardiac contraction, cause bronchoconstriction

Used in HTN, PVD, Raynaud s disease,

dysrhythmias

Monitor HR, BP

Use with caution in patients with COPD

Adrenergic Blockers

Alpha 1 blockers

Prazosin HCl (Minipress), Doxazosin HCl (Cardura),Terazosin HCl (Hytrin)

Alpha 1, Beta 1 & 2 blockersCarvedilol (Coreg), Labetalol (Trandate)

Beta 1 blockers

Metoprolol tartrate (Lopressor), Atenolol (Tenormin)

Beta 1 & 2 blockers

Propanolol (Inderal), Nadolol (Corgard)


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VS monitoring; ECG for baseline

Assess for respiratory problems

Observe for and prevent orthostatic

hypotension

Advise clients to avoid abruptly stopping

a beta -blocker & to monitor blood sugarDose -related changes in male sexual

function may occur

Cholinergic Drugs

Cholinergic stimulants, cholinergic agonists,parasympathomimetics - they mimic acetylcholine

Stimulate the PNS. Major action is to stimulate bladderand GI tone, constrict pupils (miosis) and increaseneuromuscular transmissions to receptor sites

Acetylcholine (ACh) neurotansmitter located at theganglions and parasympathetic nerve endings

Two cholinergic receptors:

Muscarinic receptors stimulate smooth muscle(eye, GIT, urinary system) and slow heart rate

Nicotinic receptors - affect skeletal muscle

Acetylcholine (ACh) &Cholinesterase (ChE)

Acetylcholine (ACh) - neurotransmitter

Cholinesterase (ChE) promotes breakdown

of ACh

Cholinesterase destroys acetylcholine.More cholinesterase, less acetylcholine

available.

Inhibit cholinesterase, more acetylcholineavailable.

Direct -acting Cholinergics

Bethanecol (Urecholine ) increases

urination

Metoclopramide HCl (Reglan) treats

gastro -esophageal reflux disease

(GERD) by increasing gastric emptyingtime

Pilocarpine causes miosis; used in

treating glaucoma

Bethanechol Cl (Urecholine)

Treats urinary retention and abdominal distention ;promotes micturition and increases peristalsis in theGIT

Poorly absorbed in the GIT. Given on empty stomach.

Voiding occurs 30 minutes 1 hrs after poadministration and 15 minutes after SC

SE: N/V, hypotension, bradycardia ,

diarrhea, salivation, sweating, flushing,

frequent urination, rash, miosis, blurred vision

Contraindication: intestinal or urinary tract obstruction,asthma

Reversible Cholinesterase Inhibitors

Produces miosis to treat glaucoma

Increases muscle strength in myasthenia

gravisNeostigmine (Prostigmine ), Pyridostigmine bromide

(Mestinon ), Edrophonium Cl (Tensilon )

CAUTION : bradycardia , asthma, PUD,

hyperthyroidism

CONTRAINDICATION: intestinal / urinary tract

obstruction


Assess urine output, bowel & breath sounds

Assess for asthma, PUD, urinary & intestinalobstruction

Monitor BP, pulse orthostatic hypotension

Give 1 hour ac or 2 hours pc

Check serum lipase, amylase

Cholinergic overdose: sweating, salivation,flush, abdominal cramps

Antidote: Atropine sulfate (0.6mg)

Anticholinergics

Parasympatholytics, cholinergic blockingagents

They inhibit the actions of acetylcholine

Major responses are to decrease GI motilityand salivation , to dilate pupils and to increasepulse rate; may cause decreased bladdercontraction

Used to treat the early stages of Parkinson sdisease and to decrease tremors and rigidity &to decrease salivation and drooling

CONTRAINDICATION: Glaucoma


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Atropine sulfate

Derived from the belladonna plant

Vagolytic inhibits vagal stiumulation

Used as a pre -op med, anti -spasmodic,treatment of bradycardia; for mydriasis &cycloplegia

Give IV undiluted or with 10 cc sterile water at0.6 mg/min

SE: dry mouth, decreased perspiration, blurred

vision, tachycardia, constipation, urinaryretention

Anticholinergic Drugs

Belladona

Hyoscyamine sulfate

Scopolamine hydrobromide

Patch used for prevention of n/v amongadults with motion sickness

Antiparkinson - AnticholinergicDrugs

Used to treat the early stages of Parkinson sdisease and to decrease tremors and rigidity &

to decrease salivation and drooling

Used in the treatment of pseudoparkinsonismin psychotropic drugs

Trihexyphenidyl HCl (Artane)

Biperiden HCl (Akineton)

Benztropine mesylate (Cogentin)


Assess PR, UO, bowel sounds

Encourage void before taking medication

Maintain adequate fluid intake

Encourage to eat foods high in fiber

Encourage activity. Avoid hot environment.

Oral care. Ice chips. Hard candy.

Avoid caffeine, alcohol, cigarettes, aspirinbefore bedtime

Safety precautions drowsiness is common

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