PNS Flashcards
Which is longer in the PNS the post or preganglionic fibers
The preganglionic fibers are longer than the post ganglionic fibers as the parasympathetic ganglia is close to the effector organ
What type of receptors does the PNS HAVE
Muscarinic and Nicotinic
What are nicotinic receptors coupled with
Na+ /K+ ion channels
What are muscarinic receptors coupled with
G proteins
What are the effects of activation of muscarinic or nicotinic receptors
DUMB HAVES DEFECATION URINATION MUSCLE EXCITATION BRONCHOSPASM HEART BRADYCARDIA AUTONOMIC GANGLIA STIMULATION VASODILATION EYE MIOSIS AND ACCOMMODATION SECRETIONS
how does the vasodilation occur after muscarinic activity
M3 receptor activation increases Ca2+ release which aids in NO formation, leading to CGMP formation ——> relaxation
How do direct cholinomimitics work
Mimic ACH
What is bethanchol
An ester
bethanechol receptors
Only muscarinic receptors
bethanechol indications
ileus and urinary retention
bethanechol contraindications
Kidney and gallstones
What is pilocarpine
Alkaloid
Pilocarpine receptors
Primarily acts on muscarinic receptors
Pilocarpine indications
Glaucoma by decreasing IOP which is done by:- Increase out flow if AH Decreased production of AH Other indications: sjorgen/xerostomia by increasing secreations of lacrimal and salivary glands
What is carbachol
Ester
Carbachol receptors
Muscarinic and nicotinic
More potent and more side effects so not used
What is methancholine
An ester
Methacholine receptors
Acts on muscarinic receptors
Methacholine uses and why is it used this way
Screening tool for bronchial asthma, methacholine challenge test.
It is short acting susceptible to ACHE degradation
Methacholine contraindications
COPD, peptic ulcer, urinary retention, GI obstruction and IHD
How to treat muscarinic poisoning exacerbated DUMB HAVES
reversed by atropine 1-2 mg every 30 mins
How do indirect cholinomimitics work
Inhibition of ACHE
What could indirect cholinomimitics be
Organophosphates - used as pesticides
Carbamates - tertiary or quartenary amines
Tertiary amines can cross BBB
What are the quaternaryamines
Edrophonium, neosrigmine and pyridostigmine
Edrophonium indication and why is it used this way
Diagnosis of myasthenia gravies
Differential diagnosis between cholinergic crisis and myasthenia graves
Since it’s a short acting competitive inhibitor of ACHE
What’s the treatment of myasthenia graves
Pyridostigmine
Neosrigmine indication
Myasthenia gravis , postoperative ileus and urinary retention and to reverse paralysis after Anastasia
What are the tertiary amines
Donepezil, galantamine, rivastigmine and physostigmine
Physostigmine indication
Antidote for over does on anti cholinergic drugs like Atropine- treat side effects like
- constipation, urinary retention and tremor and confusion
Galantamine and rivastigmine indication
Alzheimer’s disease
Side effects of indirect cholinomimitics
MIOSIS, diarrhea, urination, bronchospasm and increase secreations also convulsions, coma and CVS depression
Pralidoxime indication
Promotes regeneration of ACHE enzymes but it’s slow acting and doesn’t cross BBB
Atropine indications
Used for bradycardia, decrease bladder contraction, dilates pupils for ophthalmology and cycloplagia
Antidote for ACHE inhibitors
Atropine side effects
Tachycardia, constipation and urinary retention, dry mouth and eyes as well as blurry vision
Atropine contraindication
Narrow angle glaucoma
Oxybutinin and tolterodie indication
Decrease muscle contraction to prevent urge incontinence and involuntary urination
Ipratropium and tiotropium indication
Bronchodilators as they cause smooth muscle relaxation to relive COPD and asthma
Scopolamine indications
Prevents motion sickness and block short term memory(anaesthetic procedures)
Benztropine and trihexyphenadyl indications
Used in Parkinson’s disease as they’re active in the striatum to restore balance between ACH and Dopamine
Acetylcholine esterase where is it found
Found in many types of conducting tissue in RBC membrane but not in plasma
What is pseudocholinesterase
Also known as plasma cholinesterase
Present in plasma and works on the hydrolisis of succinylcholine
Topicamide and cyclopentolate indication
Ophthalmology - mydriasis and cycloplegia
Antidote for neuromuscular blocking drugs
Edrophonium, pyridostigmine and neostigmine
Example of non depolarising neuromuscular blocker
Tubocurarine
-curare
Example of depolarising neuromuscular blocker
Succinylcholine
Succinylcholine adverse effects and when does it happen
Malignant hyperthermia, prolonged apnea mostly seen in people with a genetic defect deficiency of plasma pseudocholinesterase
Trospium indications
Treatment of overactive bladder with Alzheimer’s disease
How to treat sinus bradycardia
Atropine
