Podcast
Questions and Answers
What is the primary mechanism of action of organophosphorus compounds in causing toxicity?
What is the primary mechanism of action of organophosphorus compounds in causing toxicity?
Which of the following symptoms is NOT associated with organophosphorus poisoning?
Which of the following symptoms is NOT associated with organophosphorus poisoning?
What is the role of atropine in the treatment of organophosphorus poisoning?
What is the role of atropine in the treatment of organophosphorus poisoning?
Which type of drug is atropine categorized as?
Which type of drug is atropine categorized as?
Signup and view all the answers
What is a key component of the treatment protocol for cholinergic toxicity?
What is a key component of the treatment protocol for cholinergic toxicity?
Signup and view all the answers
Which of the following is a potential outcome of organophosphorus poisoning if left untreated?
Which of the following is a potential outcome of organophosphorus poisoning if left untreated?
Signup and view all the answers
How do cholinesterase reactivators function in relation to organophosphorus poisoning?
How do cholinesterase reactivators function in relation to organophosphorus poisoning?
Signup and view all the answers
Which one of the following conditions is a contraindication for the use of atropine?
Which one of the following conditions is a contraindication for the use of atropine?
Signup and view all the answers
What characterizes neostigmine compared to physostigmine?
What characterizes neostigmine compared to physostigmine?
Signup and view all the answers
In which condition is edrophonium primarily used?
In which condition is edrophonium primarily used?
Signup and view all the answers
What is a common side effect of physostigmine?
What is a common side effect of physostigmine?
Signup and view all the answers
Which of the following is NOT a use for neostigmine?
Which of the following is NOT a use for neostigmine?
Signup and view all the answers
Which of the following anticholinesterases is associated with hepatotoxicity?
Which of the following anticholinesterases is associated with hepatotoxicity?
Signup and view all the answers
What is a characteristic feature of glorifying activities with neostigmine?
What is a characteristic feature of glorifying activities with neostigmine?
Signup and view all the answers
How is cholinergic toxicity from anticholinesterases typically treated?
How is cholinergic toxicity from anticholinesterases typically treated?
Signup and view all the answers
What is the predominant effect of physostigmine in the eye?
What is the predominant effect of physostigmine in the eye?
Signup and view all the answers
Which of the following statements regarding the pharmacokinetics of cholinergic agents is true?
Which of the following statements regarding the pharmacokinetics of cholinergic agents is true?
Signup and view all the answers
What is a primary effect of organophosphorus poisoning?
What is a primary effect of organophosphorus poisoning?
Signup and view all the answers
Which statement accurately describes anticholinesterases?
Which statement accurately describes anticholinesterases?
Signup and view all the answers
Physostigmine is primarily used in clinical settings to treat which condition?
Physostigmine is primarily used in clinical settings to treat which condition?
Signup and view all the answers
In the treatment protocols for cholinergic toxicity, which medication is commonly used as an antidote?
In the treatment protocols for cholinergic toxicity, which medication is commonly used as an antidote?
Signup and view all the answers
Which of the following synthetic choline esters is NOT effective when given intravenously or intramuscularly?
Which of the following synthetic choline esters is NOT effective when given intravenously or intramuscularly?
Signup and view all the answers
What effect does acetylcholine have on blood vessels?
What effect does acetylcholine have on blood vessels?
Signup and view all the answers
Which of the following is a contraindication for cholinergic agents?
Which of the following is a contraindication for cholinergic agents?
Signup and view all the answers
Study Notes
Parasympathetic Nervous System
- Often described as the "Feed and Breed" or "Rest and Digest" portion of the autonomic nervous system (ANS).
- Maintains essential body functions, like digestion and waste elimination.
- Acts to oppose or balance the actions of the sympathetic division.
Parasympathetic Neurotransmitters and Receptors
- Acetylcholine (ACh) is the primary neurotransmitter.
- ACh stimulates muscarinic receptors.
- Parasympathomimetics (also called cholinomimetic drugs) stimulate muscarinic receptors.
Parasympathomimetic Classification
-
Direct Acting:
- Choline esters: Natural (acetylcholine), synthetic (methacholine, carbachol, bethanechol)
- Natural alkaloids: Pilocarpine.
-
Indirect Acting (Anticholinesterases):
- Reversible: Edrophonium (rapidly acting), neostigmine, physostigmine, pyridostigmine (slowly acting).
- Irreversible: Insecticides (parathion, malathion), war gases (soman, tabun), Anti-bilharzial (metrifonate), Anti-Glaucoma (echothiophate).
Acetylcholine Function
- Postganglionic neurotransmitter in the parasympathetic nervous system.
- Preganglionic neurotransmitter for both sympathetic and parasympathetic systems.
- Neurotransmitter at non-autonomic sites (e.g., stimulating skeletal muscle, brain/spinal cord).
Cholinergic Transmission
- Synthesis, release, and degradation of ACh are crucial.
Pharmacokinetics of Parasympathomimetics
- Many are not absorbed orally (ionized quaternary ammonium compounds).
- Do not pass the blood-brain barrier.
- Broken down by cholinesterase enzymes.
Pharmacological Actions (Parasympathomimetics)
-
Muscarinic Actions:
- Eye: Miosis (pupil constriction), accommodation for near vision, increased lacrimation, decreased intraocular pressure (IOP).
- Cardiovascular System (CVS): Decreased heart rate and conduction, vasodilation, hypotension.
- Gastrointestinal (GIT) System: Increased motility and tone, increased secretions.
- Bronchi: Bronchoconstriction.
- Exocrine Glands: Increased secretions (salivary, sweat, lacrimal, etc.)
- Uterus: Increased contraction (non-pregnant).
-
Nicotinic Actions:
- Autonomic ganglia and adrenal medulla: Increased response, hypertension possible.
- Motor end plate: Skeletal muscle twitches.
Natural Alkaloids (e.g., Pilocarpine)
- Excreted unchanged in the urine
- Not hydrolyzed by cholinesterases.
- Primarily direct muscarinic effects.
- Functions include increased secretions (sweat, saliva) miosis, Increased contractility of bronchi, intestines, and urinary bladder.
Anticholinesterases
- Reversible: Compete with acetylcholine (Ach) at binding sites, block inactivation temporarily; hydrolyzed more slowly
- Irreversible: Form very stable complexes with cholinesterases; permanently inhibit enzyme activity; potentially toxic.
Treatment of Organophosphorus Poisoning
- Endotracheal intubation, artificial respiration
- Avoid further exposure, decontamination procedures (washing)
- Atropine administration (mucarinic blocking)
- Cholinesterase reactivators (e.g., oximes)
- Anticonvulsants (e.g., diazepam)
Parasympathetic Antagonists (Anticholinergics)
- Antimuscarinics: Primarily block muscarinic actions of acetylcholine.
- Ganglionic Blocking Agents: Block parasympathetic and sympathetic neurotransmission at ganglia.
- Neuromuscular Blocking Agents: Block neuromuscular junction.
Parasympathetic Antagonist Examples
- Atropine: Prototype. Blocks muscarinic receptors, and is widely used as pre-anesthetic medication, and in the treatment of various conditions.
- Scopolamine: Similar to atropine but has greater CNS effects.
Scopolamine
- Differences from atropine:
- More CNS depressant effects (sedation, amnesia, anti-motion sickness).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the intricate details of the parasympathetic nervous system, often referred to as the 'Feed and Breed' or 'Rest and Digest' system. This quiz covers essential functions, neurotransmitters, receptors, and the classification of parasympathomimetics. Test your knowledge on how this system balances the sympathetic division in our body.
