Podcast
Questions and Answers
What type of receptors do both the sympathetic and parasympathetic nervous systems use at the synapses between preganglionic and postganglionic neurons?
What type of receptors do both the sympathetic and parasympathetic nervous systems use at the synapses between preganglionic and postganglionic neurons?
Which drug is a non-competitive antagonist of autonomic nicotinic ACh receptors?
Which drug is a non-competitive antagonist of autonomic nicotinic ACh receptors?
What is the primary effect of Muscarinic M2 receptors in cardiac muscle?
What is the primary effect of Muscarinic M2 receptors in cardiac muscle?
Which of the following actions is NOT associated with muscarinic agonists?
Which of the following actions is NOT associated with muscarinic agonists?
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Which subtype of muscarinic receptors is primarily found in the stomach and salivary glands?
Which subtype of muscarinic receptors is primarily found in the stomach and salivary glands?
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What structural characteristic differentiates nicotinic ACh receptors in the autonomic nervous system from those in skeletal muscle?
What structural characteristic differentiates nicotinic ACh receptors in the autonomic nervous system from those in skeletal muscle?
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Hexamethonium has largely fallen out of use mainly due to what reason?
Hexamethonium has largely fallen out of use mainly due to what reason?
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What is a potential consequence of muscarine poisoning?
What is a potential consequence of muscarine poisoning?
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What is the primary action of NAT inhibitors on norepinephrine (NA)?
What is the primary action of NAT inhibitors on norepinephrine (NA)?
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Which of the following side effects is NOT associated with MAO inhibitors?
Which of the following side effects is NOT associated with MAO inhibitors?
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What potential effect can occur from consuming cheese while taking MAO inhibitors?
What potential effect can occur from consuming cheese while taking MAO inhibitors?
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Which drug is commonly known to function as a NAT inhibitor?
Which drug is commonly known to function as a NAT inhibitor?
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What is a common effect of sympathetic amines on the body?
What is a common effect of sympathetic amines on the body?
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Which of the following best describes the role of MAO in the presence of norepinephrine?
Which of the following best describes the role of MAO in the presence of norepinephrine?
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Which class of drugs is structurally similar to norepinephrine and can lead to increased release of NA?
Which class of drugs is structurally similar to norepinephrine and can lead to increased release of NA?
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What could be a consequence of prolonged use of DAT and SERT inhibitors like cocaine?
What could be a consequence of prolonged use of DAT and SERT inhibitors like cocaine?
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Which of the following symptoms is NOT associated with extreme parasympathetic effects?
Which of the following symptoms is NOT associated with extreme parasympathetic effects?
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What is the primary action of atropine when used in poisoning cases?
What is the primary action of atropine when used in poisoning cases?
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Pilocarpine is primarily used to treat which condition?
Pilocarpine is primarily used to treat which condition?
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Which of the following is a muscarinic antagonist used to manage bradycardia?
Which of the following is a muscarinic antagonist used to manage bradycardia?
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The effects of which class of drugs can be countered by using muscarinic agonists?
The effects of which class of drugs can be countered by using muscarinic agonists?
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Which receptor is responsible for causing vasoconstriction through Gq pathway activation?
Which receptor is responsible for causing vasoconstriction through Gq pathway activation?
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What is the primary effect of beta-2 adrenoceptors?
What is the primary effect of beta-2 adrenoceptors?
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What is the role of α2 receptors in the sympathetic nervous system?
What is the role of α2 receptors in the sympathetic nervous system?
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What is the primary mechanism through which β3 adrenoceptors achieve their effects?
What is the primary mechanism through which β3 adrenoceptors achieve their effects?
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Which of the following is a therapeutic use of α1 adrenoceptor agonists?
Which of the following is a therapeutic use of α1 adrenoceptor agonists?
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Which drug is commonly used to treat hypertension by acting on α1 receptors?
Which drug is commonly used to treat hypertension by acting on α1 receptors?
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What is a common use for β2 adrenoceptor agonists?
What is a common use for β2 adrenoceptor agonists?
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What physiological role does noradrenaline play in the sympathetic nervous system?
What physiological role does noradrenaline play in the sympathetic nervous system?
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Which drug targets β1 receptors specifically to improve cardiac function?
Which drug targets β1 receptors specifically to improve cardiac function?
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Which enzyme is primarily responsible for synthesizing noradrenaline from tyrosine?
Which enzyme is primarily responsible for synthesizing noradrenaline from tyrosine?
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Which condition is treated by β-adrenoceptor antagonists?
Which condition is treated by β-adrenoceptor antagonists?
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Study Notes
Autonomic Nervous System Drugs
- Drugs targeting the entire autonomic nervous system affect both sympathetic and parasympathetic branches.
- Nicotinic ACh receptors are found at synapses between preganglionic and postganglionic neurons in both these branches.
- Nicotinic ACh receptors are pentameric transmembrane ion channels. Skeletal muscle AChRs use α1 subunits while ANS receptors use α2-7 subunits.
- Hexamethonium is a non-competitive antagonist for nicotinic ACh receptors in the autonomic nervous system. It blocks both sympathetic and parasympathetic effects, but not the effects on skeletal muscle.
Parasympathetic Nervous System Drugs
- Postganglionic neurons of the parasympathetic nervous system (PaNS) use muscarinic ACh receptors to affect effectors.
- Muscarinic receptors consist of 7 transmembrane domains and are G-protein-coupled.
- M1 receptors are found in the stomach and salivary glands, using Gq and activating phospholipase C (PLC), while M2 receptors are in cardiac muscle, using Gi to inhibit adenylyl cyclase and reduce cAMP.
- M3 receptors are in smooth muscle (eyes, bronchi) and exocrine glands, using Gq and activating PLC.
- Muscarinic agonists (parasympathomimetics) mimic parasympathetic stimulation, causing decreased heart rate, vasodilation, smooth muscle contraction (gut, respiratory tract), salivation, lacrimation and bronchial mucous secretions.
Sympathetic Nervous System Drugs
- Sympathetic postganglionic neurons utilize noradrenaline (NA) as a neurotransmitter.
- Adrenoceptors are G-protein-coupled receptors. There are five types: α1, α2, β1, β2, and β3.
- α1 receptors cause smooth muscle contraction (vasoconstriction) using Gq and activating PLC.
- α2 receptors cause vasoconstriction, inhibit NA release, and modulate sympathetic outflow via Gi and inhibiting adenylyl cyclase.
- β1 receptors increase heart rate and contractility using Gs and activating adenylyl cyclase and increase cAMP.
- β2 receptors relax smooth muscle (bronchi, blood vessels, bladder) using Gs and activating adenylyl cyclase and increase cAMP.
- β3 receptors also relax smooth muscle, especially in the bladder and stimulate lipolysis, using Gs and activating adenylyl cyclase and increase cAMP.
Catecholamine Regulation Drugs
- Synthesis of noradrenaline (NA) proceeds from tyrosine with dopamine as an intermediate.
- NA acts on receptors then is reabsorbed into the presynaptic bulb via NA transporter protein (NAT), to terminate its action.
- Some NA is broken down by monoamine oxidase (MAO) enzymes.
- NAT inhibitors prevent reuptake of NA, causing prolonged sympathetic effects.
- MAO inhibitors block the breakdown of NA enhancing sympathetic effects and increasing NA levels in the presynaptic neurons.
- Sympathomimetic amines are structurally similar to NA and mimic NA actions, by entering neurons and displacing NA to increase its effect.
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Description
Test your knowledge on the drugs influencing the autonomic nervous system, including both sympathetic and parasympathetic branches. This quiz covers key receptors such as nicotinic and muscarinic ACh receptors, their functions, and specific drug interactions.
