Autonomic Nervous System Flashcards
sympathetic nerves originate from
thoracic and lumbar regions
parasympathetic nerves originate from
cranial and sacral regions
__________ nerves contain short preganglionic neurons and long postganglionic neruons
sympathetic
__________ nerves contain long preganglionic neurons and short postganglionic neurons
parasympathetic
sympathetic preganglionics are __________
cholinergic
sympathetic postganglionics are ___________
adrenergic
parasympathetic preganglionics are ___________
cholinergic
parasympathetic postganglionics are ___________
cholinergic
sympathetic postganglionic release
norepinephrine
sympathetic postganglionic stimulate
alpha and beta receptors
sympathetic postganglionic are metabolized by
MAO and COMT
parasympathetic postganglionic release
acetylcholine
parasympathetic postganglionic stimulate
muscarinic receptors
parasympathetic postganglionic are metabolized by
cholinesterase
What is a quarternary group?What is it’s significance?
1) When there are 4 C attached to a N
2) It has a charge and is therefore polar (i.e. does no go through lipids; cannot be transported into the CNS)
Benchmark parasympathetic responses
1) miosis
2) vasodilation of arterioles
3) negative chronotropic and negative ionotropic responses in heart
4) bronchoconstriction
5) SLUD (salivation, lacrimation, urination, diarrhea)
**this is all d/t muscarinic stimulation
Benchmark sympathetic responses
1) positive iontropic and positive chronotropic responses in heart (Beta 1 stim.)
2) bronchodilation (Beta 2 stim.)
3) relaxation of myometrium (Beta 2 stim.)
4) insulin release (Beta 2 stim.)
5) vasoconstriction of arterioles (Alpha 1 stim.)
6) mydriasis (Alpha 1 stim.)
7) NE release (Alpha 2 stim.)
Type(s) of parasympathomimetic drug(s)
muscarinic agonists
cholinesterase inhibitors
Type(s) of parasympatholytic drug(s)
muscarinic antagonists
Acetylcholine category
ANS - parasympathomimetic
Acetylcholine MOA
muscarinic and nicotinic agonist
Acetylcholine distinguishing characteristics
1) rapidly hydrolyzed by esterases b/c it has a ‘naked ester’
2) acts on both muscarinic and nicotinic receptors
3) quaternary ammonium group invokes polarity (can’t pass thru BBB)
Acetylcholine predictable characteristics
1) short half life (seconds)
2) diffuse activity (parasympathomimetic, sympathomimetic, and sk. mm.)
3) limited distribution
4) possible local opthalmic use, but other products better
Bethanechol (urecholine) category
ANS - parasympathomimetic
Bethanechol (urecholine) MOA
muscarinic agonist
Bethanechol (urecholine) distinguishing characteristics
1) not metabolized by esterase enzymes
2) quaternary ammonium compound
3) particular affinity for gut and bladder sm. mm.
4) oral route preferred
Bethanechol (urecholine) predictable characteristics
1) no CNS effect
2) half life allows distribution to areas of low blood flow
3) uses: gastroparesis (postoperative), urinary retention, xerostomia, ocular diagnostics
4) s/e: other parasympathomimetic effects esp. following parenteral Rx
Pilocarpine category
ANS - parasympathomimetic
Pilocarpine MOA
muscarinic receptor agonist
Pilocarpine distinguishing characteristics
1) plant origin (Pilocarpus jabarundi)
2) tertiary ammonium compound
3) preferential activity of sweat glands
4) resistance to esterases
Pilocarpine predictable characteristics
1) used as miotic and in tx of glaucoma
2) will cz accommodation
3) used to tx xerostomia
4) may cz CNS effects at high plasma levels
5) diaphoresis is common s/e
6) duration of action is up to 8 hr
Neostigmine category
ANS - parasympathomimetic
Neostigmine MOA
reversible cholinesterase inhibitor (i.e. it attaches to cholinesterases w/ a weak ionic bond)
Neostigmine distinctive characteristics
1) quaternary ammonium compound
2) contains ester group - slowly hydrolyzed (1-2 hr half life)
3) poorly absorbed following oral rx
Neostigmine predictable characteristics
1) elevates Ach levels
2) cz both muscarinic and nicotinic stimulation
3) numerous peripheral s/e but not CNS
4) uses: miosis and glaucoma (local admin.), myasthenia gravis, antidote to some drugs (atropine), atonic gut and bladder
Malathione category
ANS - parasympathomimetic
Malathione MOA
irreversible cholinesterase inhibitor (binds to cholinesterase with a covalent bond)
Malathione distinguishing characteristics
1) tertiary ammonium compound
2) binds covalently to esterase enzymes
3) not hydrolyzed by esterase enzymes
4) rapidly absorbed thru multiple routes
Malathione characteristics
1) cz SLUD and other ANS activities
2) cz CNS disturbances
3) no therapeutic use
4) used as insecticide
5) similar agents used as chemical weapons
6) atropine is antidote plus supportive therapy
Atropine category
ANS - parasympatholytic
Atropine MOA
muscarinic receptor antagonist
Atropine distinguishing characteristics
1) Tertiary ammonium compound
2) Ester group required for activity
3) resistance to hydrolysis by esterases
4) metabolized in liver with half life of about 4 hr
Atropine predictable characteristics
1) CNS toxicity esp. in children (even after ophthalmic rx)
2) inhibit SLUD and other parasympathetic activities
3) used in ophthalmology - mydriasis and cycloplegia
4) used as antidote to parasympathomimetics
5) used to tx diarrhea
6) once used to tx asthma, but now better drugs available
Ipratropium (Atrovent) category
parasympatholytic
Ipratropium (Atrovent) MOA
muscarinic antagonist
Ipratropium (Atrovent) distinguishing characteristics
1) quaternary ammonium compound
2) minimal inhibition of mucociliary clearance
3) one of MC rx drugs
Ipratropium (Atrovent) predictable characteristics
1) no CNS effects
2) bronchodilation - used to tx asthma and COPD
3) limited mucous accumulation
Scopolamine category
ANS - parasympatholytic
Scopolamine MOA
muscarinic receptor antagonist
Scopolamine distinguishing characterics
1) from plant source - Hyocyamus niger
2) Greater CNS distribution than atropine
3) other characteristic similar to atropine
Scopolamine predictable characteristics
1) greater CNS s/e and abuse potential than atropine
2) used less frequently than atropine
3) used to tx motion sickness
Type(s) of sympathomimetic drug(s)
- alpha agonists (alpha 1 and alpha 2 )
- beta agonists (beta 1 and beta 2)
- alpha and beta agonist
- monamine oxidase inhibitors
Type(s) of sympatholytic drug(s)
- adrenergic antagonists (alpha antagonists, beta 1 and 2 antagonists, beta 1 antagonist)
- adrenergic depletor (reserpine)
Epinephrine category
ANS - sympathomimetic
Epinephrine MOA
stimulate alpha and beta receptors (G protein which facilitate second messengers)
Epinephrine distinguishing characteristics
1) metabolized in gut, blood and multiple tissues
2) more beta and less alpha activity than NE
Epinephrine predictable characteristics
1) ineffective orally
2) very short half-life (minutes)
3) cardiac emergencies
4) bronchospasm - drug of choice for anaphylaxis
5) adjunct to local anesthesia
6) s/e: tachycardia, increased force of contraction, BP disturbance (usu. HTN)
Is Epinephrine a good drugs for asthma?
NO
although it bronchodilates, it also vasoconstricts so it increases BP and strain on ht.; epi is too broad in its action to be used for asthma tx
Phenylephrine (Neosynephrine) category
ANS - sympathomimetic
Phenylephrine (Neosynephrine) MOA
alpha 1 receptor agonist
Phenylephrine (Neosynephrine) distinguishing characteristics
1) effective orally
2) limited access to CNS
Phenylephrine (Neosynephrine) predictable characteristics
1) nasal decongestant
2) mydriatic
3) s/e: rebound congestion, increased peripheral resistance (don’t use in HTN pt.), reflex bradycardia (d/t carotid reflex)
Clonidine (Catapres) category
ANS - sympathomimetic ?
(actually reduces NE released b/c it’s an alpha 2 receptor agonist…so although it’s stimulating adrenergic receptors, it’s actually causing more of a parasympathetic response)
Clonidine (Catapres) MOA
alpha 2 receptor agonist
Clonidine (Catapres) distinguishing characteristics
1) effective orally
2) crosses BBB
3) prefers alpha receptors in brainstem
4) long half-life and duration of action
5) Diminish d/c from medular vasomotor center
Clonidine (Catapres) predictable characteristics
1) antihypertensive
2) s/e: dry mouth, sedation, sexual dysfn
Isoproterenol (Isuprel) category
ANS - sympathomimetic
Isoproterenol (Isuprel) MOA
beta 1 and 2 receptor agonist
more selective than EPI b/c it stimulates beta but not alpha receptors
Isoproterenol (Isuprel) distinguishing characteristics
1) metabolized by COMT
2) short duration of action
3) both beta 1 and beta 2
Isoproterenol (Isuprel) predictable characteristics
1) cardiac arrest
2) actions include tachycardia and bronchodilation
3) replaced often by more selective beta agonists - it was used to tx asthma d/t bronchodilation, but it also cz tachycardia and in asthma there is already a strain on the heart
Albuterol (Ventolin) category
ANS - sympathomimetic
Albuterol (Ventolin) MOA
Beta 2 receptor agonist
thus we can get bronchodilation w/out tachycardia
Albuterol (Ventolin) distinguishing characteristics
1) effective orally or by inhalation
2) limited cardiovascular effects
3) duration of action several hours
Albuterol (Ventolin) predictable characteristics
1) bronchodilator
2) s/e: weak and occasional tachycardia, vasodilation
Amphetamine category
ANS sympathomimetic
Amphetamine MOA
stimulates release of NE and dopamine
Amphetamine distinguishing characteristics
1) enters CNS
2) inhibits MAO
Amphetamine predictable characteristics
1) alpha and beta stimulation by NE (vasoconstriction, cardiac stimulation, incr. BP, mydriasis)
2) CNS stimulation (euphoria, insomnia, anxiety, loss of appetite, hyperthermia)
3) tx: narcolepsy, obesity, ADHD
4) high abuse potential makes it scheduled substance
Phenelzine (Nardil) category
ANS - sympathomimetic
Phenelzine (Nardil) MOA
monoamine oxidase inhibitor
MAO is the main enzyme responsible for breaking down catecholamines - Epi, NE, dopamine
Phenelzine (Nardil) distinguishing characteristics
1) readily absorbed
2) crosses BBB
3) increases synaptic catecholamine levels
Phenelzine (Nardil) predictable characteristics
1) antidepressant
2) s/e: sympathomimetic actions
Types of sympatholytics
**not on exam
1) adrenergic antagonists (alpha antagonist, beta 1 and 2 antagonist, beta 1 antagonist)
2) adrenergic depletor
Prazocin (Minipress) category
**not on exam
ANS - sympatholytic
Prazocin (Minipress) MOA
**not on exam
alpha 1 receptor antagonist
Prazocin (Minipress) distinguishing characteristics
**not on exam
1) effective orally
2) highly protein bound (5% free)
3) reflex tachycardia
Prazocin (Minipress) predicted characteristics
**not on exam
1) tx HTN
2) s/e: hypotension, syncope
Propranolol (Inderal) category
**not on exam
ANS - sympatholytic
Propranolol (Inderal) MOA
**not on exam
Beta 1 and 2 receptor antagonist
Propranolol (Inderal) distinguishing characteristics
**not on exam
1) very lipid soluble
2) significant 1st pass metabolism
3) highly variable plasma levels
4) multiple uses (not all very predictable)
Propranolol (Inderal) predictable characteristics
**not on exam
1) use: antihypertensive, anti-angina, anti-arrythmic
2) s/e: place asthma pt. at risk, place diabetics at risk
Metoprolol (Lopressor) category
**not on exam
ANS - sympatholytic
Metoprolol (Lopressor) MOA
**not on exam
Beta 1 receptor antagonist
Metoprolol (Lopressor) predictable characteristics
**not on exam
1) antihypertensive w/out risk to asthmatics and diabetics
Reserpine category
**not on exam
ANS - sympatholytic
Reserpine MOA
**not on exam
promotes release of NE and reduces reuptake resulting in depletion of NE stores
Reserpine distinguishing characteristics
**not on exam
1) derived from plant
2) transitory sympathomimetic followed by prolonged sympatholytic effect
3) antiquated for therapeutic use, extensive research use
Reserpine predictable characteristics
**not on exam
1) antihypertensive
2) s/e: prolonged paralysis of sympathetic nervous system