ANS Flashcards
This is the primary NT of PNS - released at ALL autonomic ganglia, at PNS nej, somatic nmj, and some SNS nej.
ACh
This is the primary NT of SNS - released at most SNS nej.
NE/NA
This NT is released from adrenal medulla in response to activation of SNS.
Epi
This is an important NT in CNS - released at several peripheral SNS fibers.
DA
These ANS NTs are found in enteric nervous system of GI tract, GU tract, airways, and some blood vessels - includes peptides, ATP, GABA, substance P, NO, serotonin.
Nonadrenergic noncholinergic neurons (NANC)
What effect does SNS have on the pupil?
Alpha 1 receptor -> mydriasis
What effect does PNS have on the pupil?
Muscarinic receptor -> miosis
What effect does SNS have on HR?
Beta-1 receptor -> HR increases
What effect does PNS have on HR?
Muscarinic receptor -> HR decreases
What effect does SNS have on arteries/veins?
Alpha-1 receptor -> constriction
Beta-2 receptor -> dilation
What effect does PNS have on arteries/veins?
Muscarinic receptor -> dilation
What effect does SNS have on smooth muscle?
Beta-2 receptor -> decrease motility (smooth muscle relaxation; bronchioles in lung)
What effect does PNS have on smooth muscle?
Muscarinic receptor -> increases motility
What effect does SNS have on gastric secretion?
Beta receptor -> Inhibit gastric secretion
What effect does PNS have on gastric secretion?
Muscarinic receptor -> Stimulate gastric secretion
What effect does SNS have on pancreas secretion?
Alpha receptor -> Inhibit pancreas secretion
What effect does PNS have on pancreas secretion?
Muscarinic receptor -> Stimulate pancreas secretion
What effect does SNS have on salivary secretion?
Alpha-1, Beta receptor -> Inhibit salivary secretion
What effect does PNS have on salivary secretion?
Muscarinic receptor -> Stimulate salivary secretion
What effect does SNS have on the liver?
Alpha-1, Beta-2 receptors -> Glycogenolysis, Gluconeogenesis
What effect does PNS have on the liver?
Muscarinic receptor -> Glycogenesis
These receptors are found at PNS nej, some SNS nej (sweat glands), CNS and autonomic ganglia.
Muscarinic receptors
- Found in body in greater #s than nicotinic receptors
What are muscarinic receptors activated by?
ACh + muscarine
What results from stimulation of muscarinic receptors?
Salivation
Lacrimation
Urination
Defacation
GI motility
Erection
These receptors excite neurotransmission on autonomic ganglia and mediate muscle contraction on somatic nmj.
Nicotinic receptors
What are nicotinic receptors activated by?
ACh + nicotine
This type of receptor constricts vascular smooth muscle and blood vessels, increases basal metabolic rate, and is located at SNS nej effector (primarily smooth muscle).
Alpha-1 adrenergic receptor
This type of receptor involves inhibition of NE release from nerve endings at presynaptic post ganglionic neuron (neg. feedback), and is located at some postsynaptic tissue and blood platelets.
Alpha-2 adrenergic receptor
This type of receptor mediates cardiac stimulation (increases HR and contractility), is located on SNS effector (cardiac muscle, vascular smooth muscle, renal cells - increase renin release), and increases lipolysis.
Beta-1 adrenergic receptor
This type of receptor mediates smooth muscle relaxation, is located on SNS effector (bronchioles in lung, uterine smooth muscle and vascular smooth muscle), and in liver/muscle increases glycogenolysis.
Beta-2 receptor
This type of drug activates postsynaptic receptors.
Direct agonists
This type of drug stimulates release of NT, inhibits reuptake of NT, or inhibits metabolism of NT.
Indirect agonist
This type of drug blocks postsynaptic receptors.
Direct antagonists
This type of drug inhibits synthesis of NT, prevents vesicular storage of NT, or inhibits release of NT.
Indirect antagonist
What are choline esters and plant alkaloids?
Direct cholinergic agonists (bind + active cholinergic receptors)
What are cholinesterase inhibitors?
Indirect cholinergic agonists (increase synaptic concentrations of ACh)
What are the choline esters?
- ACh + Carbachol -> activates nicotinic + muscarinic
- Bethanechol + Methacholine -> activates only muscarinic
Which direct cholinergic agonist stimulates bladder w/o significant effects on HR or BP, and is used in tx of urinary retention post-op/post-partum?
Bethanechol (a choline ester)
Which direct cholinergic agonist is used for chronic open-angle glaucoma and to produce miosis during opthalmic surgery?
Carbachol (a choline ester)
What are the plant alkaloids?
- Muscarine (no current medical use)
- Nicotine (smoking cessation)
- Pilocarpine
- Cevimeline
Which direct cholinergic agonist has a higher affinity for muscarinic receptors and treats glaucoma by stimulating contraction of ciliary muscle fibers -> increases aqueous humor outflow -> decreases intraocular pressure?
Pilocarpine
Which direct cholinergic agonist is used to treat dry mouth associated with Sjogren’s syndrome?
Cevimeline
What is Donepezil?
Reversible cholinesterase inhibitor (indirect cholinergic agonist)
Tx of Alzheimer’s
What is Edrophonium?
Reversible cholinesterase inhibitor (indirect cholinergic agonist)
Dx of Myasthenia gravis (very short DOA)
What is Neostigmine?
Reversible cholinesterase inhibitor (indirect cholinergic agonist)
Tx of Myasthenia gravis, antidote for skeletal muscle relaxants
What is Physostigmine?
Reversible cholinesterase inhibitor (indirect cholinergic agonist)
Tx overdoses of drugs w/ anticholinergic effects (i.e. atropine, TCAs)
What is Pyridostigmine?
Reversible cholinesterase inhibitor (indirect cholinergic agonist)
Tx of Myasthenia gravis
What are the irreversible cholinesterase inhibitors (organophosphates)?
- Ecothiophate (tx of chronic refractory glaucoma)
- Pesticides (palathion and malathion)
- Soman (chemical warfare agent)
What does organophosphate poisioning cause?
- All effects of muscarinic activation (SLUDGE, spasm, bronchoconstriction, decreased HR + CO)
- Cholinergic activation in CNS -> seizures, respiratory depression, coma
- Excessive activation of nicotinic receptors -> neuromuscular blockade + muscle paralysis
What is the tx for organophosphate poisoning?
- Symptomatic - maintain VS
- Decontamination
- Antidotes - atropine to counteract ACh + pralidoxime (2-PAM) to regenerate cholinesterase
What are atropine, scopolamine, and hyoscyamine?
Bella Donna Alkaloid muscarinic receptor antagonists
What are ipratropium, tolterodine, oxybutynin, propantheline, dicyclomine, benzotropine?
Synthetic/Semi synthetic muscarinic receptor antagonists
What ocular effect do Atropine, Tropicamide, and Scopolamine have?
Mydriasis, dry eyes (muscarinic receptor antagonist - inhibits lacrimal gland)
What cardiac effect does Atropine have?
Increases HR + AV conduction (muscarinic receptor antagonist; tx for sinus bradycardia + AV block)
What respiratory effect do Ipratropium and Titotropium have?
Increase bronchodilation (muscarinic receptor antagonist; tx for COPD, emphysema, bronchitis)
What GI effects do Hyoscyamine, Donnatal, and Dicyclomine have?
Relax GI muscle, reduce intestinal motility, inhibit gastric acid secretion (muscarinic receptor antagonist; tx for intestinal spasms/pain)
What urinary tract effects do Oxybutynin, Tolterodine, Darifenacin, and Solifenacin have?
Urinary retention (muscarinic receptor antagonistic; tx for dysuria + urinary incontinence)
What CNS effects does the Scopolamine patch have?
Block cholinergic transmission from vestibular apparatus to vomiting center (muscarinic receptor antagonist; tx for motion sickness)
What CNS effects does Benztropine and Trihexyphenidyl have?
Reduce tremor (muscarinic receptor antagonist; tx for Parkinsons), causes sedation, confusion, altered mental state
What is Trimethaphan?
Ganglionic blocker (nicotinic receptor antagonist)
- limited use due to adverse effects
- used rarely for HT emergency
What are curariforms (i.e. Atracurium, Pancuronium, and Vecuronium)?
Nondepolarizing neuromuscular blocking agents (nicotinic receptor antagonists)
- Reversible by cholinesterase inhibitors
What is succinylcholine?
Depolarizing neuromuscular blocking agent (nicotinic receptor antagonist)
- Irreversible
What do the catecholamines (epi, NE, isoproterenol, DA, dobutamine) act as?
Direct acting adrenergic agonists
- Rapidly metabolized by MAO + COMT enzymes in gut, liver, other tissues (must be given parenterally)
What do the non-catecholamines (albuterol, clonidine, phenylephrine, and terbutaline) act as?
Direct acting adrenergic agonists
What do amphetamine, cocaine, and tyramine act as?
Indirect adrenergic agonists
What is epinephrine?
adrenergic agonist
direct
catecholamine
binds all adrenergic receptors
vasoconstricts, increases BP (alpha1)
cardiac stimulation (beta1)
bronchodilation + skeletal muscle vasodilation (beta2)
tx: anaphylactic shock and cardiac arrest
What is norepinephrine?
adrenergic agonist
direct
catecholamine
vasoconstricts, increases BP (alpha1)
cardiac stimulation (beta1)
tx: hypotension and shock
What is isoproterenol?
adrenergic agonist
direct
catecholamine- not a specific beta agonist
cardiac stimulation (beta1)
bronchodilation (beta2)
tx: asthma, AV block, bradycardia
What is dopamine?
adrenergic agonist
direct
catecholamine
precursor to NE and Epi
renal vasodilation (delta1)
increases BP (alpha1)
cardiac stimulation (beta1)
tx: cardiogenic shock, septic shock, heart failure, adjunct to fluid administration in hypovolemic shock
What is dobutamine?
adrenergic agonist
direct
catecholamine
highest affinity for beta1
less activity at alpha1
tx: cardiogenic shock, cardiac arrest, heart failure
What is phenylephrine?
adrenergic agonist
direct
noncatecholamine
vasoconstricts, increases BP, mydriasis (alpha1)
tx: nasal decongestant, ocular decongestant, maintains BP during surgery
What is albuterol?
adrenergic agonist
direct
noncatecholamine
bronchodilation (beta2)
tx: asthma
What is clonidine?
adrenergic agonist
direct
noncatecholamine
inhibits NE release from nerve terminal of postganglionic neuron (feedback inhibition- alpha2 antagonizes alpha1)
tx: chronic HTN and can have CNS effects (sedation)
What is terbutaline?
adrenergic agonist
direct
noncatecholamine
bronchodilates and uterine relaxation (beta2)
tx: asthma and premature labor (tocolytic- to suppress labor/anti-contractions)
What is amphetamine?
adrenergic agonist
indirect
increases release of NE and DA from SNS neurons
vasoconstricts, cardiac stim, and increases BP
penetrates CNS-CNS stim (increases mood/alertness) but decreases appetite
What is cocaine?
adrenergic agonist
indirect
local anesthetic
stimulates SNS by blocking reuptake of NE and DA in the PNS and SNS- similar effects to amphetamine
What is tyramine?
adrenergic agonist
indirect
normal byproduct of tyrosine metabolism in the body
in fermented food (cheese, red wine, beer, salami, pepperoni)
indirect sympathomimetic because it causes the release of stored catecholamines
normally metabolized by MAO
*if we are taking an MAO inhibitor, avoid tyramine-containing foods
What is pseuoephedrine?
adrenergic agonist
mixed
vasoconstricts (alpha1)
increases the release of NE from SNS neurons
tx: nasal decongestant
What is phenoxybenzamine?
nonselective alpha adrenergic antagonist
blocks alpha1 and alpha2
noncompetitive, irreversible
tx: HTN episodes assoc with pheochromocytoma (tumor in adrenal medulla that secretes catecholamines)
What is phentolamine?
nonselective alpha adrenergic antagonist
blocks alpha1 and alpha2
competitive, reversible
dx and tx: HTN episodes from pheochromacytoma
tx: necrosis and ischemia from extravasations of Epi
What is “azosin”?
selective alpa 1 adrenergic antagonist
relax vasc smooth muscle and smooth muscle in bladder and prostate
produce vasodilation and decrease bp
tx: HTN and urinary retention due to BPH
agents include: doxazosin, prazosin, terazosin, (tamsulosin and alfuzosin - only for BPH)
What are propanolol, nadolol, and timolol (“olol”)?
nonselective beta adrenergic antagonists
blocks beta1 in the heart and beta2 in smooth muscle, liver, etc.
beta1 blockade: decreases BP, CO, renin release, aqueous humor secretion
beta2 blockade: bronchoconstriction, decreases glycogenolysis, masks signs of hypoglycemia
tx: HTN, angina, arrythmias, MI, migraine, glaucoma
What are atenolol and metoprolol (“olol”)?
selective beta1 adrenergic antagonist
primarily in cardiac tissue
produce less bronchoconstriction and other beta2 receptor mediated effects
tx: HTN, angina, MI
What is carvedilol?
mixed alpha + beta adrenergic antagonist
tx: HTN and CHF
What is labetalol?
mixed alpha + beta adrenergic antagonist
tx: HTN
