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Home , Acetylcholine, Adrenergic, Anticholinergic, Cholinergic

1/30/2012

Adrenergic and

Nervous System

Central Peripheral nervous system ( and ) ( outside the brain and spinal cord)

Efferent Afferent

Autonomic nervous system

Sympathetic Parasympathetic nervous system nervous system () (cholinergic)

1 1/30/2012

Functions of the ANS • Involuntary System • Responsible for: – Control of (e.g., bronchi,,,) blood vessels, GI tract) – – Exocrine glands (e.g., gastric, sweat, salivary) • Monitored by both the sympathetic and parasympathetic nervous systems

Autonomic Nervous System • Balanced antagonism between the sympathetic and parasympathetic nervous systems. • A needs to bind with an appropriate site on the effector organ or to produce effect • This is accomplished by synaptic transmission.

Synaptic Transmission • Synthesis of in the nerve terminal. • Neurotransmitter is stored awaiting an . • Action potential causes release • Neurotransmitter diffuses across the synaptic gap

2 1/30/2012

Synaptic Transmission (cont) • Reversibly binds to postsynaptic cell receptor and exerts an effect • Neurotransmitter is dissociated from its binding site by a variety of mechanisms. • The neurotransmitter is now degraded or experiences “” for reuse.

Neurotransmitters • (Ach) • (NE) • Epinephrine (Epi) •Dopp(pamine (precursor to NE)

3 1/30/2012

NE

Receptor Names • Stimulated by Ach= Cholinergic • Stimulated by NE= Adrenergic

Sympathetic Nervous System •Mostly stimulated by NE –Direct –Indirect • Sympathomimetic • Catacholamines • Noncatecholamines • Adrenergic receptors

4 1/30/2012

Adrenergic Receptors • Alpha-1, alpha-2, beta-1, and beta-2. • Drugs that stimulate the receptors are called . • DthtblkthtDrugs that block the receptors are called antagonists or blockers. • Most drugs stimulate or block more than one receptor at a time. • Some drugs are relatively selective in their stimulation or blockade.

Stimulation of Alpha-1 Receptors • Stimulation causes: – Vasoconstriction – Increased peripheral resistance – Increased (BP) – Pupil dilation () – Closure of the internal sphincter of the bladder • Blocking causes the opposite effects.

5 1/30/2012

Stimulation of Alpha-2 Receptors • Causes: – Decreased release of NE, reducing sympathetic outflow from brain – VdiltiVasodilation • Blocking causes the opposite effects.

Stimulation of Beta-1 Receptors • Causes: – – Increased myocardial contractility – Increased lipolysis • Blocking causes the opposite effects.

Stimulation of Beta-2 Receptors • Causes: – Bronchodilation – – Slightly decreased peripheral resistance – Increased muscle and liver glycolysis – Increased release of – Relaxation of uterine smooth muscle • Blocking causes the opposite effects.

6 1/30/2012

Which of the adrenergic receptors shuts off NE when stimulated? A. Alpha 1 B. Alpha 2 C. Beta 1 D. Beta 2

Which of the following is in the sympathetic nervous system? a. Norepinephrine (NE) b. (DA) c. Beta 2 receptors d. All of the above

Parasympathetic Nervous System (PSNS) • Acetylcholine is the neurotransmitter. •Direct •Indirect

7 1/30/2012

Cholinergic Receptors • Muscarinic: – Concentrated in the heart, smooth muscle, and exocrine glands • Nicotinic – Found in the (CNS), the , autonomic ganglia, and the adrenal medulla

Which of the following describes a that stimulates the parasympathetic system? A. PSNS B. PSNS C. Cholinergic D. All of the above

8 1/30/2012

PSNS Terms: a rose is a rose • Drugs that stimulate PSNS receptors: – –Agonists – • Drugs that block PSNS receptors: –Blockers –Antagonists –

Cholinergic Effects • Decreased • (constriction of pupil) •Sweating • Increased salivation • Increased bronchial secretions • Bronchial constriction

Cholinergic Effects (cont) • Increased GI tone • • Decreased BP • Bradycardia • Contraction of bladder detrusor muscle

9 1/30/2012

Anticholinergic Effects • Increased intraocular pressure • Mydriasis (dilation of pupils) • • Decreased sweating •Dry mouth • Decreased bronchial secretions • Respiratory depression

Anticholinergic Effects (cont) • Decreased GI motility with possible • Decreased BP followed by increased BP • Tach ycardi a and , possibl y, pal pit ati ons • • Vasodilation • Drowsiness, confusion, and agitation

Excess Anticholinergic Mnemonics • Mad as a hatter • Blind as a bat • Red as a beet • Dry as a bone

10 1/30/2012

Drug Actions

• Attaches to the neurotransmitter receptor sites • Drug effect from stimulating/blocking receptor

ADRENERGIC Drugs Epinephrine • Nonselective : – Stimulates all alpha and beta receptors

Ask a nurse! • Why would you want to give a drug that stimulates all alpha and beta receptors? • What adverse effects would you expect to be common?

11 1/30/2012

ADRENERGIC Drugs Epinephrine • Many therapeutic uses, such as: – Cardiopulmonary arrest – Ventricular fibrillation –Anaphylactic shock – • Adverse effects related to stimulation of all receptors are common. • CNS and cardiac adverse effects are the most common and may be the most serious.

ADRENERGIC DRUGS • Alpha-1 stimulant

You are giving an alpha 1 stimulant (such as phenylephrine) via IV infusion into the left hand. The IV line goes bad, and “infiltrates”. •What adverse effects could occur? •What nursing management is needed to minimize adverse effects?

12 1/30/2012

Put it together!

• Why don’t we just turn off infusion and elevate the hand after infiltration of phenylephrine? • Why is this different than if D5.45 NS infiltrates?

ADRENERGIC DRUGS Phenylephrine • Alpha-1 stimulant • Potent vasoconstrictor • Avoid IV extravasation • Pharmacotherapeutics include: – Vascular failure – Hypotension –Shock states • Topical pharmacotherapeutics: – Nasal – Pupil dilation (mydriasis)

Prazosin Alpha-1 blocker • What effect does the drug have on blood vessels? On blood pressure? • What nursing actions are needed to minimize adverse effects?

13 1/30/2012

ADRENERGIC DRUGS Dopamine- Nonselective alpha 1 and beta-1 stimulant

• Also sti mul at es d opami nergi c recept ors • Increases cardiac output • Low doses- don’t see alpha 1 effects, just • Higher doses see alpha 1 effects

Dopamine • This is a . • How will you need to administer this drug?

ADRENERGIC DRUGS Nonspecific - relatively selective for Beta 1

• Which type of adverse effects might be common to both of these drugs? • Which adverse effects would be more likely to occur with propranolol?

14 1/30/2012

Put it together!

If you discontinue a beta blocker abruptly what might happen to the heart?

CHOLINERGIC DRUGS- MUSCARINIC • What effect would topical preparations have?

CHOLINERGIC DRUGS-NICOTINIC

• Stimulates the CNS. • Pharmacotherapeutics are limited to preparations to assist in . • Adverse effects are related to its effects on the cardiovascular system and CNS.

15 1/30/2012

CHOLINERGIC DRUGS - Indirect-acting cholinergic

• Acts by reversibly inhibiting postsynaptic () • What serious adverse effects would be seen with an overdose? • What would be the ?

CHOLINERGIC DRUGS - Anticholinergic • Anticholinergic effects • Antidote to cholinergic poisoning • Pharmacotherapeutics: – Preoperatively to dry secretions – Acute cardiac emergencies – Topically () to treat ophthalmic disorders – Treatment of and diarrhea

CHOLINERGIC DRUGS Atropine - Anticholinergic

• What is responsible for adverse effects from this drug? • Which age group is most sensitive to anticholinergic adverse effects? • What can the nurse do to minimize adverse effects?

16 1/30/2012

Atropine (cont)

• Adverse effects related to loss of acetylcholine stimulation on receptors • Most serious adverse effect: anticholinergic overdose (poisoning)

Put it together! Why is atropine ( anticholinergic ) given pre-op? A. To cleanse the GI tract B. To prevent aspiration of oral secretions C. To induce miosis D. To prevent motion sickness

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