Peripheral Nervous System-PSNS Flashcards
Norepinephrine is released from _____________
Synaptic nerve endings
Epinephrine is released fromm __________
Adrenal glands
Nicotinic receptors are ____________ and can be found where?
Ionotropic
Neuromuscular junction
CNS and autonomic ganglia
Muscarinic receptors are ______________
Metabotropic
What are the most common locations of M1 receptors
GI smooth muscle
Urinary Bladder
Myocardium
Exocrine glands
Activation of muscarinic receptors can cause ________ signs
S alivation L acrimation U rination D igestion D efecation
Adernergic receptor a1 are most common where??
Vascular smooth muscle Vasocontriction Increase BP Mydriasis Sphincter constriction Glycogenolysis
Adrenergic receptors a2 are most common where?
Brain and spinal cord
Vascular endothelium
Endocrine organs
Decrease insulin
Decrease renin
Decrease NE release
Decrease pancreatic secretion
Adrenergic receptor B1 are most common where?
Myocardium
Adipose tissue
Increase HR and contractility
Lipolysis
Smooth m. Relaxation
Increase renin -> increase BP
Adrenergic receptors B2 are most common where?
Airway smooth m.
Vasculular smooth m.
Brochodilation Vasodilation Smooth m relaxation Increase blood to skeletal muscle Cyclopelegia Glycogenolysis Increase insulin Increase NE release
What is a mimetic drug?
Drugs that stimulate autonomic effects (agonist)
What is a lytic drug
Drugs that block autonomic effects (antagonistic)
Autonomic drugs act directly by acting on the _______________
Receptor
Indirect acting drugs interact with _____________
Substances other than the receptor
Eg enzymes
What receptor on the heart cause increased heart rate, increased contractility, and increased conduction of the AV node
Sympathetic B1
Activation of what receptor on the vasculature will cause vasoconstriction
Sympathetic a1
Activation of what receptor on the vasculature will cause vasodilation
Sympathetic B2
Activation of what receptor in the lungs causes bronchodilaton ?
sympathetic B2
Activation of what receptors of the GI tract will cause decreased motility, close sphincters, and inhibit secretions
Sympathetic a1, B1, and B2
Activation of what receptor causes relaxation of the detursor muscle
Sympathetic B2
Activation of what receptor of the urinary bladder causes sphincter contraction
Sympathetic a1
What are acetylcholine effects
Bradycardia (neg chronotropy) Decrease BP (neg ionotropy) Increase GI motility and secretion Smooth muscle contraction -uterus/bladder/bronchioles/iris Increased secretions Convulsions in CNS Stimulate autonomic ganglia and adrenal medulla Skeletal muscle contraction
What is the most commonly used direct acting Parasymathomimetic drug?
Bethanechol
What receptor and action will Bethanechol work on
Muscarinic receptor agonist
Stimulate contraction of detrusor muscle of urinary bladder
What are the indications of Bethanechol?
Increase urinary bladder muscle contractility (detrussor m atony)
Increase GI motility
Treat dysautonomia
Resproductive cases -uterine contraction
When should Bethanechol not be used?
Urethral/urinary tract obstruction
Or GI obstruction
What are the parasympathomimetics reversible anticholinesterases?
Neostigmine
Pyridostigmine
Edrophonium
What is the onset and duration of action of neostigmine ?
Relatively short onset
Humans effects in 10-30min and last for 4 hrs
What are the indications of neostigmine?
Reversal agent of choice for reversal of competitive neuromuscular blockers
Stimulate GI motility and bladder emptying
Treat myasthenia gravis in dogs
Treat rumen atony
What are some precautions to be aware of when using Neostigmine
SLUDD signs
May be dramatic in patients with pre-existing hight vagal tone
When is Neostigmine used contraindicated
Peritonitis
GI obstruction
Late pregnancy
Presence of other cholinesterase inhibitors
What is the mechanism of action of Neostigmine?
Indirect
Anticholiesterase
Choliesterase inhibitor
What is the mechanism of action of Pyridostgmine
Indirect parasymatthomimetic
Anticholiesterase
Choliesterase inhibitor
How does the onset and duration of pyridostigmine compare to neostigmine
Neostigmine = short (3min after oral dose and last 4hrs)
Pyridostigmine= 1hr after oral dose and lasts 8-12hrs
Used for maintenance therapy
What are the indications for Pyridostigmine
Treatment of choice for myasthenia gravis in dogs -> long term maintenance therapy
What are precautions of pyridostigmine ?
SLUDD, typically GI
pre-existing high vagal tone
What is the mechanism of action of Edrophonium
Indirect acting parasympathomimetic
Cholinesterase inhibitor
Anticholinesterase
What is the onset and duration of Edrophonium
Very fast acting-> onset in 1 min
Very short duration-> 10mins
What are the indications for Edrophonium
Tensilon test
What are the precautions of Edrophonium
Cholinergic SLUDD signs
Less commonly, more severe cholinergic crisis -> bronchoconstriction/secretions, bradycardia or tachycardia, hypotension, cardiac arrest
What are the parasymathomimetics that are irreversible
Echothiophate (ophthalmic) Organophosphate insecticides (toxicity)
What are the muscarinic effects of organophosphate toxicity
SLUDD
Diarrhea Dyspnea Urination Miosis Bronchospasm Bradycardia Emesis Lacrimation
What are the nicotinic effects of organophosphate toxicity
Muscle tremors
Muscle weakness
Muscle paralysis (including respiratory)
CNS effects
What re the direct acting parasymatholytics?
Atropine
Glycopyrrolate
Oxybutynin
Probantheline
What are the effects of atropine?
Tachycardia Mydriasis (pupil dilation) Dries secretions Reduce salvation Slow gut Bronchodilaton Blurred vision Difficulty with urination
What is the mechanism of action of atropine sulfate?
Direct acting parasympaholytic
Antimuscarinic
Atropine sulfate is a ______________ compound that can cross the BBB
Tertiary
What are the indications for atropine sulfate
Treat bradyarrhythmias/bradycardia
Cardiac arrest (not CPR cases)
Treatment of acetylcholinesterase inhibitor toxicity (organophosphate, carbamates)
Treatment of cholinergic crisis/anticholinesterase overdose
What are the precautions of Atropine sulfate
Transient drop in HR after IV injection
May cause tachycardia or exacerbate tachyarrhythias
Rabbits have endogenous atropinases
What are the contraindications to using atropine sulfate
Glaucoma
Tachycardia, tachyarrhythmias
Hypothermic bradycardia patients
Certain GI disease, obstructive uropathy, myasthenia gravis
What is the mechanism of action of Glycopyrrolate
Direct acting parasympatholytic
Antimuscarinic
Glycopyrrolate is a _______________ compound and does not cross the BBB
Quaternary
What is the onset and duration of action of glycopyrrolate?
Slower onset and longer duration than atropine
What are the indications to using glycopyrrolate
Same as atropine -slower kinetics
Pre-med in anesthesia
Reduce hypertension
What are the precautions of using Glycopyrrolate
Same as atropine
Less likely to cause CNS effect -> quaternary compound
Less arrhythmogenic than atropine
Duration of action is LONGER
What is the mechanism of action of Oxybutynin and Prpantheline
Direct acting parasympatholytic
Antimuscarinic
Oxybutynin wide distribution-> cross BBB
Propantheline does not cross BBB
What are the indications for Oxybutynin and propantheline
Main: urinary antispasmodic to treat detrusor muscle instability (hyperactive bladder)
Propantheline also used to treat certain bradyarrhythmias
What are contraindications to using oxybutynin and propantheline
Can cause other parasympatholytic signs but at normal dose => bladder and GI tract appear to be most affected
Glaucoma
Tachycardia
Ileus
What drug is antispasmodic for GI indications
Aminopetamide
What drug is antispasmodic for colic in horse
N-butylscopolammonium bromide
What is the treatment of choice for myasthenia gravis
Pyridostigmine
What is used to test myasthenia gravis?
Edrophonium
Closed-angle glaucoma is a contraindications to the use of __________
Atropine
T/F: atropine lasts longer than glycopyrrolate
False
Glycopyrrolate lasts longer than atropine
