NRSG 305 Flashcards

Flashcards of vocabulary terms about Parasympathetic Nervous System, Cholinergic Agonists, and Anticholinergic Agents

Acetylcholinesterase

Enzyme responsible for the immediate breakdown of acetylcholine when released from the nerve ending.

Alzheimer's disease

Degenerative disease of the cortex with loss of acetylcholine-producing cells and cholinergic receptors; characterized by progressive dementia.

Cholinergic agonist

Substance that mimics actions of acetylcholine.

Miosis

Constriction of the pupil; relieves intraocular pressure in some types of glaucoma.

Myasthenia gravis

Autoimmune disease characterized by antibodies to cholinergic receptor sites leading to destruction of the receptor sites and decreased response at the neuromuscular junction; it is progressive and debilitating, leading to paralysis.

Nerve gas

Irreversible acetylcholinesterase inhibitor used in warfare to cause paralysis and death by prolonged muscle contraction and parasympathetic crisis.

Parasympathomimetic

Mimicking the effects of the parasympathetic nervous system leading to bradycardia, hypotension, pupil constriction, increased gastrointestinal secretions and activity, increased bladder tone, relaxation of sphincters, and bronchoconstriction.

Choline

Nerves use this from our diet to make acetylcholine

Acetylcholine (ACh)

The only neurotransmitter in the parasympathetic nervous system

Conservation of energy

Overall goal of the PSNS

Effects of PSNS stimulation

Increased GI motility, Increased GI secretions, Increased Defecation, Increased Urination, Decreased HR, Dilates blood vessels, Decreased cardiac contractility (rest), Bronchoconstriction, Increased pulmonary secretions, Constrict pupils

Acetylcholine (ACh)

Communicates between the nerves and the muscles

Acetylcholine (ACh)

Triggers the action of contraction

Acetylcholine (ACh)

Involved in thought processes such as thought, learning and memory

Acetylcholine (ACh)

Associated with awakening

Acetylcholinesterase (AChE)

Breaks down ACh

Acetylcholinesterase (AChE)

Prevents the overstimulation of the cholinergic receptor sites

Nicotinic N, M & Muscarinic1, 2, 3

Two receptor subtypes

Muscarinic

Activated by muscarine

Muscarinic

Found in visceral effector organs (GI tract, bladder, heart, sweat glands, vascular smooth muscle)

Muscarinic stimulation causes

Pupil constriction, Increased GI motility/secretions, Increased saliva, Increased bladder contraction, Decreased HR

Nicotinic

Located in the CNS, adrenal medulla, autonomic ganglia, and neuromuscular junction

Nicotinic stimulation causes

Skeletal muscle contraction, Autonomic responses (s/s stress reaction), Release of norepinephrine and epi from adrenal medulla

Acetylcholine

Acts on 2 receptors: muscarinic (mAchR) & nicotinic (nAChR)

Muscarinic Receptors

Muscarinic acetylcholine receptors

Muscarinic receptors

Classified from M1 to M5

M1

CNS, Salivary glands, Parietal cells

M2

Heart

M3

Smooth muscle, Exocrine glands

Vasodilatation

All smooth muscle contraction except

M1 Function

CNS Excitation Rate Memory Locomotor activity

M2 Function

Force AV conduction

M3 Function

Glandular secretion Gastric acid secretion

M4 and M5

Mainly present within the CNS and their exact role still unknown

Nicotinic Receptors

Nicotinic acetylcholine receptors

Nicotinic receptors

Classified as N,G and M types

NN

CNS

NG

Adrenal medulla Autonomic ganglia

NM

Skeletal muscle

NN Function

CNS Excitation

NG Function

Ganglionic transmission Release of adrenaline

NM Function

Skeletal muscle contraction

Cholinergic Agonists

Act at same site as neurotransmitter acetylcholine (ACh)

Cholinergic Agonists

Increase activity of ACh receptors throughout the body

Cholinergic Agonists

Drug effects cannot be limited to specific site, and effect is widespread…often undesirable systemic effects

DIRECT-ACTING CHOLINERGIC AGONISTS (MUSCARINIC)

PSNS Drugs

DIRECT-ACTING CHOLINERGIC AGONISTS (MUSCARINIC)

acetylcholine chloride, bethanechol, carbachol, cevimeline, pilocarpine

DIRECT-ACTING CHOLINERGIC AGONISTS (NICOTINIC) AND AGENTS FOR NICOTINE WITHDRAWAL/ABSTINENCE

bupropion, nicotine, varenicline

INDIRECT-ACTING CHOLINERGIC AGONISTS

echothiophate iodide, neostigmine, pyridostigmine

Agents for Alzheimer's Disease

donepezil galantamine rivastigmine

Cholinergic agonists

Act on ACh receptors throughout the body either directly or indirectly

Direct Cholinergic Agonists

Act at cholinergic receptors in peripheral nervous system Mimic effects of ACh and parasympathetic stimulation Occupy receptor sites for ACh on effector cells of postganglionic cholinergic nerves

Indirect Cholinergic Agonists

Cause increased stimulation of ACh receptor sites by reacting with AChE Prevents AChE from breaking down ACh

Direct Acting Cholinergic Agonists (Muscarinic) Effects

Slowed heart rate, Decreased myocardial contractility, Vasodilation, Bronchoconstriction, Increased bronchial mucus secretion, Increased GI activity/secretions, Increased bladder tone, Relaxation of GI and bladder sphincters, Pupil constriction

Bethanechol/Duvoid Therapeutic Uses

PO or SQ for nonobstructive post op and postpartum urinary retention and neurogenic bladder

Acetylcholine chloride/Miochol-E Therapeutic Uses

Opthalmic agent for eye procedures that require rapid miosis (pupil constriction) or to reduce intraocular pressure for glaucoma

Cevimeline AND pilocarpine Therapeutic Uses

Bind to muscarinic receptors (systemic) to increase secretions in the mouth and GI tract to relieve dry mouth in Sjogren’s syndrome

Nicotine/Nicorette Therapeutic Uses

Nicotine replacement therapy to aid smoking cessation

Bupropion & Varenicline/Chantix Therapeutic Uses

Aid in smoking cessation

Indirect Acting Cholinergic Agonists Mechanism

Prevent breakdown of acetylcholinesterase at the synapse resulting in accumulation of ACh, or inhibit metabolism of ACh causing an increase in ACh levels

Indirect Acting Cholinergic Agonists Location of action

Works at all ACh receptors (parasympathetic, CNS, and neuromuscular junction)

Reversible Indirect Examples

Pyridostigmine/Mestinon Neostigmine/Bloxiverz Donepezil/Aricept Galantamine/Razadyne Rivastigmine/Exelon

Irreversible Indirect Examples

Organophosphate/Nerve Gas/Mustard Gas/ Echothiophate

Myasthenia Gravis

Autodistruction of the nicotinic ACh receptors causing decreased muscle activity and control

Neostigmine/Bloxiverz & Pyridostigmine/Mestinon

A reversible cholinesterase inhibitor used to improve muscle strength by preventing the breakdown of ACh

Alzheimer’s

Progressive loss of ACh producing neurons in brain cortex

Atropine & Scopolamine

Block only muscarinic effectors in the parasympathetic nervous system and those in the SNS (sweating)

Therapeutic Actions of Cholinergic-Blocking drugs

Competitive antagonists….ACh is unable to bind to receptor sites and cause cholinergic effect

Expected Drug Effects of Anticholinergics

Dilated pupils (mydriasis), Decreased accommodation caused by paralysis of ciliary muscles (cycloplegia), Decrease intestinal and gastric secretions, Relax smooth muscle tone of GI tract, Decrease motility and peristalsis

Adverse Effects of Anticholinergics

Tachycardia, dysrhythmias, CNS excitation, disorientation, hallucinations, delirium, Dilated pupils, decreased visual accommodation, increased intraocular pressure

Ditropan XL / Oxybutynin Therapeutic Use

Overactive bladder: Abnormal spasm of the detrusor muscle that results in incontinence

Patient Education for Anticholinergics

Dry mouth may occur; can be handled by chewing gum, frequent mouth care, and hard candy

ATROPINE

Antidote for cholinesterase inhibitors

Anticholinergic Agents

AKA Parasympatholytic AKA Cholinergic Antagonist