autonomic nervous system chapter 17,18, 19, 20. central nervous system or cns brain and spinal cord:...
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Autonomic Nervous System
Chapter 17,18, 19, 20
Central Nervous System or CNS Brain and spinal cord: receives and
processes incoming sensory information and responds by sending out signals that initiate or modify a process.
Peripheral Nervous System
Includes all the neurons and ganglia found outside the CNS
Includes the Sympathetic receptors (adrenergic) Parasympathetic receptors (cholinergic)
Sympathetic Nervous System
Helps the body cope with external stimuli and functions during stress (triggers the flight or fight response) Vasoconstriction – increase in blood pressure Increased heart rate Increased respiratory rate Cold, sweaty palms Pupil dilation
Sympathetic Nervous System
Parasympathetic Nervous System Works to save energy, aids in digestion, and
supports restorative, resting body functions. Decrease in heart rate Increased gastro intestinal tract tone and
peristalsis Urinary sphincter relaxation Vasodilation – decrease in blood pressure
The Race Horse and the Cow
Sympathetic Nervous System
Norepinephrine and epinephrine Both always present in the blood. Norepinephrine varies according to the
amount of stress present and will cause transient changes in heart rate and systemic arteries and veins.
Epinephrine is a constant in regulating heart rate, vasoconstriction in systemic arteries and veins and vasodilation of muscles and liver.
Adrenergic Receptors
Norepinephrine produces its effects by combining with adrenergic receptors Alpha Beta
Adrenergic Receptors
Found in: Cardiovascular Endocrine Gastrointestinal Genitourinary Respiratory Ocular
Alpha Receptors
Alpha 1: adrenergic receptors located on postsynaptic effector cells. Smooth muscles of blood vessels: Constriction Bladder sphincter Penis Uterus Pupillary muscles of iris
Adrenergic Receptor
Alpha 1 Therapeutic Uses
Control topical superficial bleeding Treat nasal congestion Elevate blood pressure Delay absorption of local anesthesia Decrease intraocular pressure (pressure in eye)
Alpha 2
Same as the Alpha 1 but are located in the presynaptic nerve terminals.
Adrenergic Receptor
Beta 1 Cardiovascular
Cardiac muscle: increased contractility Atrioventricular node (AV): increased heart rate Sinoatrial node: increase (SA) in heart rate
Endocrine Pancreas (insulin)
Cardiac Conduction System
Beta 1 Drugs
Predominately works on vascular smooth muscle of the heart.
Adrenergic Receptor
Beta 2 Cardiovascular
Dilation of blood vessels Endocrine Uterine relaxation Respiratory: dilation of bronchial muscles
Beta 2 Drugs
Used in Asthma to relieve bronchocontriction. Used to delay pre-term labor by relaxing the
uterus.
Dopamine
Adrenergic neurotransmitter – essential for normal brain function. Studies focus on connection between dopamine
malfunction in schizophrenia and Parkinson’s Disease.
Role of dopamine: stimulants and depressants.
Body Responses – “fight or flight” Increase in blood pressure and cardiac
output. Increase blood flow to brain, heart and
skeletal muscles. Decrease blood flow to skin and organs not
needed for “fight”. Increase in glycogen for energy, mental
activity, muscle strength, blood coagulation, respiratory rate, pupil dilation to aid vision, and increase in sweating.
Fight of Flight Response
Can be a problem if the body stay in the “fight or flight” mode.
Type A personalities? High stress environment? Medications may be needed reduce the
physiologic body responses.
Parasympathetic Nervous System
Rest and Digest Save energy Decreased heart rate
Sympathetic Nervous System
Protective mechanisms designed to help person cope with the stress or get away from it.
Body Responses – “rest and digest” Dilation of blood vessels in skin Decrease heart rate Increase secretion of digestive enzymes Constriction of smooth muscle of bronchi Increase in sweat glands - cooling Contraction of smooth muscles of urinary
bladder Contraction of smooth muscle of skeletal
system
Adrenergic Drugs
What do they do? Stimulation of the sympathetic nervous
system.
Indications
Respiratory conditions Topical nasal congestion Ophthalmic conditions Cardiovascular
Lungs
Asthma and COPD (Chronic Obstructive Pulmonary Disease): Beta 2 drugs or bronchodilators are used to relieve broncho-constriction and broncho-spasm.
Action: dilation of bronchioles
Asthma
OTC Adrenergic Drugs
Common cold: anti-histamines Allergy: nasal or oral to relieve nasal
congestion
Heart
Direct stimulation of receptors Alpha 1 –
Vasoconstriction of blood vessels which increases blood pressure
Pressor or vasopressor effect to maintain blood pressure
Beta 1 Increased force of myocardial contraction Increased speed of electrical conduction in the heart.
Heart: SA Node
Ophthalmic Conditions
Used to reduce intraocular pressure in treatment of glaucoma.
Glaucoma
Contraindications
Only contraindications to use of adrenergic drugs are: Drug allergy Severe hypertension
Adrenergic Drugs
Epinephrine Pseudoephedrine – Sudafed Isoproterenol (Isuprel) Phenylephrine (Neo-Synephrine) Clonidine (antihypertensive)
pseudoephedrine
Trade names: Sudafed, Afrin nose spray Functional Classification: Adrenergic Therapeutic classification: allergy, cold and
cough remedies, nasal drying agents / decongestants
Action: stimulates alpha and beta adrenergic receptors
Forms and Dosage
How supplied: tabs, chew tabs, extended release tabs, liquid or drops
Dosing: 30 to 60 mg / dose q 6-8 hours PO Maximum dose 240 mg/24 hours Sustained release: 120 mg PO q 12 hours
Contraindications
Severe Hypertension Severe coronary artery disease (CAD) Use with caution in pregnancy, breast
feeding and renal failure
Side Effects
Dizziness, nervousness, restlessness, insomnia and arrhythmias
Seizures Cardiovascular collapse
Additional Information
Primarily excreted renally – adjust in patients with renal impairment
May cause false-positive for amphetamines – athletes
Currently need to ask pharmacist for Sudafed – OTC has been limited due to abuse
Nursing Implications
Assess for congestion Monitor pulse and blood pressure before
beginning therapy Assess lung sound for signs of bronchial
secretions
Allergies
Anaphylactic Shock
Epinephrine
Epinephrine would be the drug of choice Classification: Adrenergic Action: affects both the beta 1 (cardiac) and
beta 2 (pulmonary) receptors produces bronchodilation inhibits hypersensitivity reaction of mast cells.
Epinephrine
Therapeutic Effects: Bronchodilation Maintenance of heart rate and blood pressure
Adverse Side Effects: Nervousness, restlessness, tremors, angina,
arrhythmias, hypertension, tachycardia
How it is given?
Sub-Q or IV or inhaled Epi-pen is given to clients with severe allergy
reactions Not given by mouth because drug is
inactivated by gastric juices Can be inhaled in asthma attack
CAUTION!
Check dose, concentration, and route of administration fatalities have occurred from medication errors use TB syringe for subcutaneous administration
Inhaled provided as metered dose inhaler 160 to 250 mcg – can have 3 treatments 5 minutes apart.
IV would be 0.1 to 0.25 mg (cardiopulmonary resuscitation)
Calculation
The order is for 0.25 mg of epinephrine. How much would you need to draw up from
the vial: Epinephrine 1 mg / 1 ml
Precautions with Use
Tachyarrhythmia's (fast irregular heart rate), headache, nausea, and palpitations
Short acting so more definitive treatment needs to be initiated
Need cardio-respiratory monitoring Pulse oximetry Cardiac monitor
Vasopressive Drugs
Pressor drugs or “pressors” or inotropes Used to support the cardiovascular system
during cardiac failure or shock. Common vasopressors:
Dobutamine #1 Dopamine # 2 Nor-epinephrine (in addition to 1 & 2)
Dobutamine
Functional classification: Adrenergic direct acting B1 agonist, cardiac stimulant
Uses: management of heart failure caused by depressed contractibility of the heart
Action: stimulates beta 1 (myocardial) adrenergic receptors with relatively minor effect on heart rate or peripheral blood vessels.
Dopomine
Functional Classification: adrenergic Uses: to improve blood pressure, cardiac
output, urine output – treatment of shock Action: stimulates Dopomine receptors and
beta 1 adrenergic receptors Effect: increase BP, cardiac output and renal
blood flow
Adrenergic-blocking Drugs
Chapter 18
Antiadrenergic Drugs
Blocks the effects of the sympathetic nerve stimulation, endogenous catecholamine and adrenergic drugs.
Mechanism of Action
Act on alpha or beta receptors Receptors are blocked by adrenergic
antagonists or pre-synaptic alpha 2 receptors are stimulated.
When Used?
To manage hypertension and a number of cardiovascular disorders. Beta 1 blocking drugs: acute myocardial infarction
(heart attack) MI, angina (chest pain), hypertension
Alpha1 blocking drugs: heart failure, angina, hypertension
When Used?
Urinary retention – to reduce smooth muscle contraction of the bladder neck
Migraine headaches: ergotamines to dilate blood vessels of the brain and carotid arteries.
Uterine contractions: ocytocics used to control post-partum bleeding
Patient Teaching
Teach about therapeutic and adverse effects. Take medications as prescribed and do not
abruptly stop do not take more or less. Avoid caffeine and other CNS stimulants. Change positions slowly to avoid dizziness or
syncope Hypotension Postural hypotension or orthostatic hypotension
Patient Education
Avoid alcohol Hot tubs and saunas Report constipation and urinary retention Report to health care providers:
Confusion Depression Hallucinations Nightmares Palpitations Dizziness
Orthostatic Hypotension
Abnormally low blood pressure that occurs when a person assumes a standing position from a sitting or lying position.
Cholinergic Drugs: Chapter 19 Cholinergic drugs stimulate the
parasympathetic nervous system.
Mechanism of Action
Direct acting cholinergic drugs are synthetic derivative of choline.
Effects of drug Decrease heart rate, vasodilation, and changes in
BP Increase tone and contractibility of smooth muscle Increase tone and contractibility of bronchial
smooth muscles Increased respiratory secretions
Indications for Use
Urinary retention without obstruction Postoperative abdominal distention due to
paralytic ileus Myasthenia gravis – muscle weakness During surgery to reverse the effects of
muscle relaxants used during surgery
bethanechol
Trade name: Urecholine Functional classification: urinary tract
stimulant Chemical classification: cholinergic Uses: postoperative urinary retention Action: stimulates cholinergic receptors
Nursing Assessment: urine retention Urinary retention
Bladder distention Difficulty voiding
How do you know drug is working? Fluid intake equal to urine output Patient has voided within the last 8 hours
Nursing Assessment: paralytic ileus Paralytic ileus
Hypo-peristalsis Decreased bowel sounds No gas or bowel movement
How do you know drug is working? Bowel sounds heart in all four quadrants Client states has passes gas Client states has had a bowel movement
Myasthenia Gravis
Signs and symptoms: muscle weakness, ptosis (droopy eye lid), diplopia (double vision), difficulty chewing and swallowing, decreased activity intolerance.
pyridostigmine
Trade name: Mestinon and Antillrium Functional classification: antimyasthemics Chemical classification: cholinergics Indications: used to increase muscle strength
in the symptomatic treatment of myasthenia gravis
Evaluation of drug effectiveness How do you know medication is working?
Increased muscle tone No droopy eye lid or double vision Increased activity tolerance.
Alzheimer
Signs and symptoms: loss of memory, cognitive function and decreased self-care
Clinical trials with Razadyne (drug is in test stage and there is not enough evidence to show that is works)
Evaluation of medication effectiveness: Increase memory and cognitive function Increase interest in activities of daily living.
Cholinergic-Blocking Drugs
Chapter 20
Colinergic-Blocking Drugs
Anticholinergics are a class of medications that inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells.
Mechanism of Action
Drugs act by occupying receptor sites on target organs innervated by parasympathetic nervous system leaving fewer receptor sites free to respond to acetylcholine.
Parasympathetic response is absent or decreased depending on number of receptors blocked.
Effects of Anticholinergic Drugs CNS stimulation followed by depression Decreased cardiovascular response to
parasympathetic (vagal) stimulation that slows heart rate.
Bronchodilation and decrease respiratory secretions
Antispasmodic effects in GI system Change in intra-ocular pressure in patients
with glaucoma
Uses
GI disorders – peptic ulcer disease, gastritis, increased gastric acid secretion – relax gastric smooth muscle (replaced by newer drugs)
Genitourinary – anti-spasmodic – urgency Excessive secretions Ophthalmology – relax eye for exam Respiratory disorder – asthma or bronchitis –
inhaled form only Cardiac disorders – bradycardia or heart block Parkinson’s disease
Side Effects
Hyperthermia, hot, dry flushed skin, dry mouth, tachycardia, delirium, paralytic ileus and urinary retention
Atropine
Chemical classification: anticholinergic Functional classification: antiarrhythmic Action: Inhibits the action of acetylcholine at
postganglionic sites located in the smooth muscle, secretory glands, CNS. Low doses decrease: sweating, salivation and respiratory secretions.
Atropine
Therapeutic effects: Increased heart rate Decreased GI and respiratory secretions May have spasmodic action on the biliary and
genitourinary tracts.
Atropine
Side effects: Drowsiness Blurred vision Tachycardia Dry mouth Urinary hesitancy