Exam 1 Flashcards
Key Characteristics of Autonomic Nervous System
regulates involuntary response (smooth muscle, muscle, glands and heart)
2-neuron pathways
diffuse vs. discrete responses
dual innervation- opposing antagonistic effects
reflex responses
predominant, basal activity/control
Exceptions to Dual Innervation
adrenal medulla (sympathetic) most sweat glands (sympathetic only) blood vessels (sympathetic only) -basal tone -receptor distribution determines response pilorector muscle
Parasympathetic Tone is dominant in what systems?
cardiac, bronchial smooth muscle, GI tract, urinary tract, salivary glands
Sympathetic tone is dominant in what systems?
sweat glands and arterioles/veins
Adrenal Medulla
sympathetically innervated only one neuron postsynaptic neuroendocrine cells secrete epi/norepi into blood mimics sympathetic stimulation
sweat glands
sympathetic innervation
post ganglionic neuron is cholinergic (not adrenergic)
Ach is NT
receptor at effector tissue is muscarinic
Enteric Nervous system innervates the
GI tract
Steps of Neurotransmission
synthesis
storage
release (vesicles fuse w/ nerve terminal)
action
termination (reuptake, enzyme degradtion, and diffusion)
Cholinergic Transmission
synthesis from choline, acetyl-CoA storage in vesicles action potential triggers Ca2+ entry, then interacts with SNARE protein on vesicle leading to fusion of vesicle and opening/release of Ach binding to receptor termination of action recycle choline
what blocks cholinergic transmission?
botulinum toxin blocks
AchE
acetylcholinesterease
Major Types of Receptors
Ligand Gated Ion Channel
GPCR
Transmembrane w/ linked enzymatic domain
Intracellular receptor
Muscarinic Cholinergic Receptor
GCPR
5 subtypes, 2 subgroups
autonomic effector tissues (heart, endothelium, smooth muscle, glands) CNS
endogenous ligand: Ach
Activation mimics post ganglionic parasympathetic neuron stimulation
diverse cellular responses to M agonist
current drugs aren’t very selective
Nicotinic Cholinergic Receptor
ligand gated Na K depolarizing channel
major subtypes: NicM NicN
located: autonomic ganglia, skeletal muscle innervated by somatic nerves and CNS
Ach binds causing conformational changes, channel opens and + charged ions pulled through channel
depolarization of post synaptic cell
Where are cholinergic receptors?
M1 CNS M2 heart M3 Smooth muscle, glands, endothelium, eye (circular, ciliary m) M4 CNS M5 CNS NicN ANS ganglia, adrenal medulla, CNS Nicm: Skeletal muscle NMJ
Key Points of Acetylcholine
roles in peripheral and central NS
many NT sites (NMJ, ANS ganglia, effector jux of postganglionic parasympathetic neurons and CNS)
Acetylcholine Termination of Action
Termination action: AchE
Receptors: Muscarinic, NicotinicN and NicotinicM
Drug Targets:
Receptors of Acetylcholine
Muscarinic, NicotinicN and M
Drug Targets of Acetylcholine
Ach Synethesis, storage, release AchE
Muscarinic and nicotinic receptors
Drug uSes of Ach
heart, eye, lung, GI GU NMJ and CNS
Adrenergic Neurotransmission
synthesis of NE (catecholamine)
uptake/storage vesicles
release w/ action potential (indirect adrenergic drugs)
rec binding
termination of action: reuptake via NET (NE transporter)
Catecholamine from
AA tyrosine
Alpha Adrenergic Receptors
GPCR
ligands: NE, Epi and Dopamine
3 subtypes alpha1 and alpha2
Alpha 1 found in
smooth mucle
eye
Alpha 2 is
mainly presynaptic
Activation of Alpha 1
excitatory
increases Ca2+, calmodulin activity, increase actin-myosin interaction, smooth muscle contraction
Activation of Alpha 2
inhibitory
decreases cAMP, decrease NE release
Beta Adrenergic Receptor
B1 B2 B3
GCPRs Gs
activation of adenyl cyclase to increase cAMP increase kinase activation and phosphorylation
Beta Adrenergic Effector tissue
autonomic
heart kidney liver smooth muscle skeletal muscle and fat cells
Where are Alpha 1 adrenergic receptors located?
smooth muscle GU sphincters most vascular (skin, splanchnic) eye (radial msucle) heart liver
Where are alpha 2 adrenergic receptors located?
presynaptic nerve terminal
platelets
pancreatic beta cell
Where are beta2 adrenergic receptors located?
smooth muscle (bronchiolar, uterine, etc.) vascular smooth muscle skeletal muscle beds liver skeletal muscle heart
Where are beta 1 adrenergic receptors located?
heart
kidney JG cells
Where are beta 3 cells located?
adipose tissue
Key Points of NE in the peripheral nervous system
roles in peripheral and CNS (excitatory)
catecholamine NT
termination of action: reuptake back into presynaptic neuron, diffusion, metabolism- minor role (MAO/COMT)
Noradrenergic receptors (GCPR, negative feedback limits response)/alpha1/alpha2/beta1-3
Drug Targets: NE synethesis, storage, reuptake, metabolism, receptor
Drug uses: cardiovascular, respiratory
Dopamine has roles in
peripheral and CNS
Dopamine is a catecholamine NT
precursor of NE and E
at effector JXNm sympathetic renal vascular smooth muscle
TOA of Dopamine
neuronal reuptake by DA transporter
MAO breakdown
MAO A
periphery
MAO B
CNS
COMT
minor role
Dopamine Receptors
GCPR, cAMP 2nd messanger D1 class: increases cAMP D2 class (d2-d4): decreases cAMP
Dopamine in the periphery (d1)
vasodilation in renal mesenteric, coronary vasculature
Dopamine in the periphery (d2)
presynaptic, modulates NT release
Dopamine as a drug (low dose)
vasodilation
Dopamine as a drug (intermediate)
+ inotrope (B1)
Dopamine as a drug (high)
vasoconstriction (alpha1)
Other NT utilized by PNS
NO vasoactive intestingal peptide calcitonin gene related peptide neuropeptide Y substance P serotonin others
PDE5
phosphodiesterase 5; the enzyme that breaks down the 2nd messengar
eNOS
endothelial nitric oxide synthase; enzyme that makes nitric oxide from L-arginine
Iris
pupillary control iris radial (mydrasis) Sympathetic NS Iris circular (miosis) Parasympathetic NS
Ciliary
focus lens
Parasympathetic- accomodate near vision
increase outflow aqueous humor
Ciliary Body
aqueous humor production
increase secretion of aqueous humor via epithelium (sympathetic)
Aqueous Humor
intraocular pressure
adrenergic
describes neurons or receptors that use NE, or drugs that mimic sympathetic nerve stimulation
Alpha adrenergic
adrenergic receptor activated by NT NE
beta adrenergic
adrenergic receptor activated by NT NE
Catecholamine
molecule class that contains a caetchol and amine gorup, includes Epi, NE and dopamine
Cholinergic
describes neurons or receptors that use Ach or drugs that mimic parasympathetic nerve stimulation
Epipherine
adrenalin, produced in adrenal medulla, also NT in CNS
ganglion
a cluster of nerve cell bodies
muscarinic receptor
cholinergic receptor of PSNS
Nicotinic receptor
cholinergic receptor
NE
noradrenalin, NT at sympathetic effector tissues in periphery, some produced in adrenal medulla also in CNS
Preganglionic
situated before the ganglion
Postganglionic
situated after the ganglion
Characteristics of SNS
originated in the thoracolumbar 2 neurons peripheral ganglia preganglia -short post ganglia- long divergence- diffuse receptor on post gang- adrenegic/ muscarinic receptor on target tissue: sweat glands/ adrenal`
Characteristics of PSNS
Central Nervous and below and above scaral region 2 neurons ganglia locations: SC and CNS Pre- long, post short discrete divergence receptors: muscarinic, nicotinic,
Sympathomimetics
drugs with an effect that mimic stimulation of SNS or adrenal medullary discharge
Symopatholytics
drugs that antagonize the sympathetic nervous system
three ways sympathomimetics stimulate SNS
directly on adrenoreceptors
indirectly by stimulating release of noradrenaline from nerve endings
combination of both mechanisms
Direct acting Cholinergic Drugs
receptor agonist
acetylcholine
muscarine
pilocarpine
bethanechol
Direct Acting Cholinergic Direct (Nicotinic Agonist)
Acetylcholine
nicotine
succinylcholine
varenicline
Indirect Acting (AchE inhibitors)
Edrophonium
neostigmine
pyridostigmine, physostigmine
donepezil
Indirect Acting AchEi (irreversible)
echothiopate
Other Cholinergic Agonist Drugs
increased muscarinic activity
lack acetate ester function
AChE does not hydrolyze
MOA of AChE Inhibitor Drugs
Goal: to increase Ach in cleft and increase half life
bind to active site and inhibit AChE
Indirect Muscarinic and nicotinic effects
Indirect Reversible AchE inhibitor Drugs
alcohol (edrophonium)
Carbamate (neostigmine)
Indirect Irreversible AchE inhibitor Drugs
echothiophate
AchE inihbitors are reversible if
the drug covalently bonds
Short Duration Reversible AchE inhibitors
edrophonium
Medium Duration Reversible AchE inhibitors
neostigimine, pyridostigmine, physostigmine
AchE Effects
increases Ach
amplifies effects at cholinergic synapses
indirect stimulant of nicotinic receptors by increasing Ach
Clinical Uses of AchE
reversal of NM blockade by ND drug MG diagnosis and treatment glaucoma GI- ileus Postop Urinary Retention Alzheimer's Disease Non-therapeutic insecticide
AchE Inhibitor drug effect on ANS
bradycardia, bronchoconstriction, increase secretions, increase GI motility, hypotension, miosis (accomdation for near vision)
AchE Inhibitor drug effect on NMJ
reverses NM block by ND NMR blocker
improves transmission MG
large doses can depolarize block
AchE Inhibitor drug effect on CNS
therapeutic- dementia tx
toxicity- excitation
Depression follows
Edrophonium DOA, Main Site of Action, Onset, Notes
alcohol, quaternary amine, very polar Reversible blockade Injectable IV IM use for reversal Onset 30-60seconds, duration 10 mins NMJ, used for MG diagnosis
Neostigmine DOA, Main Site of Action, Onset, Notes
medium NMJ used IV to reverse used as oral treatment in MG visceral side effects carbamate, quaternary amine, moderately polar hydrolyzed by AchE, labile covalent bond IV, orally active Onset: 10-30 mins DOA 2-4 hours
Physostigmine
carbamate, tertiary amine, non-polar CROSSES BBB
hydrolyzed by AchE labile covalent bond
oral, IV/IM, useful for anticholinergic toxicity
onset 3-8 mins, duration 1 hour
medium, Peripheral, used as eye drops for glaucoma treatment
Pyridostigime
Medium
NMJ
used orally in treatment of myasthenia gravis
better absorbed than neostigmine and has longer DOA
Cholinergic Crisis
DUMB BELLS diarrhea, diaphoresis urination miosis Bradycardia Bronchoconstriction Excitation (skel m., CNS) lacrimination salivation sweating
Cholinergic Toxicity can occur
as a muscarinic toxicity treat with atropine
and AChE toxicity ( too much Ach from blocking too much inhibitor)
antidote: atropine/pralidoxime
Muscarinic Agonist Drugs
acetylcholine carbechol methacholine bethanecol muscarine pilocarpine oxotremorine cevimeline
Bethanecol is utilized for
treatment of bladder and GI hypotonia
Pilocarpine is used for
glaucoma
Cevimeline is used for
sjogen’s syndrome
Drug effects of Muscarinic Agonist (parasympomimic)
decrease HR/BP bronchoconstriction increased salivation/ lacrimination increase GI motility Miosis decrease intraocular pressure, accommodation for near vision bladder contracts
Effects and Clinical use of Muscarinic agonist
glaucoma (contract ciliary body, increase aqueous outflow humor)
postop ileus
post op urinary retention
xerostomia (dry mouth)
Effects of Muscarinic Agonist Type
salivation lacrimination urination diarrhea gi upset emesis
Do not use cholinergic drugs if
GI/GU obstruction CV disease Respiratory disease (asthma, COPD)
Effects of Nicotinic neuron Agonist
stimulation of post ganglionic neuronal activity
CNS stimulation
Clinical Use of Nicotinic neuron Agonist
Smoking cessation
Adverse effects of Nicotinic Neuron Agonist
CNS stimulation
skeletal muscle depolarization/blockade
HTN, increase HR, N/V and diarrhea
Effects of Nicotinic muscle Agonist
activation of NM endplates
contraction
Clinical Use of Nicotinic NMJ agonist
depolarizing skeletal muscle paralysis
Muscarinic Antagonist Drugs (nonselective)
atropine
glycopyrrate
scopolamine
Nicotinic Antagonist (NicotinicN)
ganglionic blocker
hexamethonium
Nicotinic Antagonist (NaChRM)
atracurium, cisatracurium, vecuronium, rocuronium, pancuronium
Muscarinic Receptor Antagoinst Effects
increase HR bronchodilation decrease GI motility GU constipation and retention Decrease sweat and glandular release pupillary dilation CNS sedation
Clinical Uses of Muscarinic Receptor Antagonist
motion sickness parkinson's disease exam requiring mydriasis cyclopegia decrease lung secretions COPD asthma GI hypermotility urinary urgency treatment of bradycardia anesthetic premed cholinergic poisoning achE inhibitor toxicity
Atropine Characteristics
tetriary amine lipophilic crosses BBB half-life about 4 hours injection (IV IM) opthalamic utilized for opthalmic, bradycardias, antidote vs cholinergic agonist, pre-op inhibits secretions adjunct for NM block reversal
Scopolamine Characteristics
tertiary amine crosses BBB CNS effects- amnesia, sedation half- life 1-4hr (IV) onset 10 mins duration 2 hours transdermal patch injection uses for motion sickness, post op NV preop- amnesia, sedation, antiemetic decrease secretions
Glycopyrrolate Characteristics
quaternary amine, decreases CNS effects half life about 1 hour onset 1 min duration (7 hours) IV oral uses include pre-op, cardiac dysrhythmia (vagal reflex association) adjunct for NM blockade
Muscarinic Antagonist/Anticholinergic Effects
Dry as a bone, hot as a pistol, red as a beet, blind as a bat, mad as a hatter
Potential concerns of Muscarinic Antagonist/Anticholinergic
hyperthermia glaucoma prostatic hypertropy CV (arrhythmias, ischemia, HF, HTN) ileus, ulerative colitis
Medication classes with anticholinergic effects
antihistamines antispasmodics antiparkinson's skeletal muscle relaxants antipsychotics antidepressants antimuscarinics for urinary incontinence
Nicotinic Receptor Antagonist Effects
competitive antagonism at skeletal muscle
Non-depolarizing
Nicotinic M Receptor Antagonist Clinical Uses
Skeletal muscle relaxation for surgical, intubation, ventilation control
Nicotinic N Receptor Antagonist Effects
Blocks ganglionic output
Nicotinic N Receptor Antagonist CLinical uses
hypertensive emergency (no longer in use)
Mechanisms of Adrenergic drugs
indirect
mixed multiple sites of action (release of NE from nerve terminal, activate adrenergic receptors, broader actions)
direct receptor antagonist
Alpha 1 second messengers and effectors
phospholipase C activation
increase inositol trisphosphate
increase diacylglycerol
increase Ca2+
Alpha 1 potency order
NE, E, iso
Alpha 1 Selective Agonist
phenylpherine
methoxamine
Alpha 1 Selective antagonist
prazosin
doxazocin
Alpha 2 second messengers and effectors
decrease cAMP, decrease Ca channels, increase K channels
Alpha 2 potency order
E, NE, ISO
Alpha 2 selective agonist
clonidine
Alpha 2 selective antagonist
yohimbine
idazoxan
Beta 1/2/3 second messengers and effectors
increase cAMP
Beta 1 potency
ISO>NE>E
Beta 2 potency
ISO > E> NE
Beta 3 potency
ISO> NE=E
Beta 1 selective agonist
dobutamine
xamoterol
Beta 1 selective antagonist
atenolol
metoprolol
Beta 2 selective Agonist
salbutamol terbutaline salemetrol formoterol clenbuterol
Beta 2 selective antagonist
butoxamine
Beta 3 selective agonist
mirabegron
Ephedrine
displaces/releases stored catecholamine NT
some agonist activity on alpha and beta receptors
noncatecholamine extended duration
herbal source-ma hung
Amphetamine
displaces/releases stored catecholamine NT
secondary inhibits catetcholamine reuptake (NET, DAT)
uses in ADHD, narcolepsy, appetite suppression
Cocaine
blocks NE reuptake (inhibits NET & DAT transporters)
Blocks sodium channels- local anesthetic actions
Tyramine
displaces/releases stored catecholamines
not a drug, in fermentated foods, role in drug food interacitons of MAO inhibitors
Tricyclic Antidepresants, SNRI
block NE re-uptake (inhibits NET transporter)
Monamine Oxidase inhibitors (MAOis)
prevents breakdown of catecholamines in presynaptic terminal- catecholamine accumulation in vesicles
MAOA metabolizes NE
MAOB metabolizes DA
tranylcypromine and phenelzine
nonselective inhibits MAOA and MAOB
Selegiline and rasagiline
selective MAOB inhibitors
Most drugs are non-catecholamines
longer acting
oral adminsitration
Epinephrine Receptor and Uses
Alpha 1 alpha 2 beta 1 beta 2 beta 3 low doses- beta effects high doses: alpha effects Anaphylaxis, w/ local anesthetics, cardiac arrest
Norepinpherine Receptors and Uses
Alpha 1 and Beta 1
shock
Isoproterenol Receptors and Uses
Beta 1 and Beta 2
acute asthma, cardiac stimulant
Dopamine Receptors and Uses
low dose: renal, mesenteric, coronary vascular beds
med doses: beta 1
higher doses: alpha 1
shock, HF and increase blood flow to kidney
Dobutamine Receptors and Uses
b1 primarily
acute HF
Cardiac Effects of NE
decrease pulse
increase SBP and DBp
Increases PVR
Cardiac Effects of Epi
increases HR
increases SBP/ decreases DBP
decreases PVR
Cardiac Effect of Isoproterenol
increases HR
increases SBP/ decreases DBP
decreases PVR
Predominant effects of Adrenergic Receptor agonist
Alpha 1
vasoconstriction smooth muscle (except GI) trophic effect (BPH) GI/GU sphincters contract Eye-mydriasis
Predominant effects of Adrenergic Receptor agonist
Beta 1
increase HR, increase contractility
effects on rhythm
kidney renin
trophic effect- hypertrophy
Predominant effects of Adrenergic Receptor agonist
Alpha 2
decrease NE release (presynaptic)
CNS inhibit sympathetic outflow
platelet aggregation
decrease insulin in pancreas
Predominant effects of Adrenergic Receptor agonist
Beta 2
bronchodilation vasodilation most smooth muscle (relaxes) skeletal muscle contracts (tremor) GI/GU relax uterine smooth muscle relax glycogenolysis
Alpha 1 agonist effects
increase vascular tone, increase PVR/BP and eyes dilate
Alpha 1 agonist clinical uses
shock
OTC: decongestants, ophthalamic hyperemia
Alpha 2 agonist clinical uses
hypertension
Alpha 2 effects
decrease NE release
Dexmedetomidine
selective alpha 2 receptor agonist (CNS actions)
suppresses sympathetic NS activity
sedative effects
analgesic effects
decrease HR, decrease SVR, decrease BP
Respiratory less RR decrease TV
tolerance, tachyphylaxis, premed, adjunct to general anesthesia,
Beta 1 Agonist Effects
increase HR, AV node conduction, increase force and renin release
Beta 1 Clinical Uses
ACUTE heart failure
Beta 2 agonist effects
relaxation or lung, uterus, vascular and liver
Beta 2 clinical uses
asthma, COPD, preterm labor
Potential concerns with adrenergic agonist
CV disease cerebrovascular disease other vasoconstriction related diabetes (increase blood glucose) IV extravasation risks thyroid disease
Nonselective alpha adrenergic receptors Blockers
phenoxybenzamine
phentolamine
Alpha 1 adrenergic receptors Blockers
prazosin
Alpha 2 adrenergic receptor Blockers
yohimibine
Nonselective Beta Blocker
propanolol
Beta 1 Receptor Blocker
Metoprolol
esmolol
Alpha Receptor Antagonist Effects
smooth muscle relaxation, decrease pVR, decrase BP
Alpha receptor antagonist Clinical uses
hypertension
BPH
pheochromocytoma
Adverse Effects of Alpha Receptor Antagonist
increase HR, first dose effect
orthostatic HTN and syncopy
Beta Receptor Antagonist Effects
decrease HE, decrease force of contraction
decrease renin release, anti-rhythmic effects
Clinical uses of beta receptor antagonist
htn, angina pectoris, arrhythmia, myocardial infaraction, thyrotoxicosis, heart failure, infantile hemangioma, glaucoma, migrane, prophylaxis, anxiety
Potential concerns of Adrenergic Antagonist
respiratory disease
cardiovascular
diabetes (may potentiate hypoglycemia and mask sign/sym)
thyroid disease