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Questions and Answers
What is the primary effect of activating A1 receptors located in the radial dilator pupillae muscle of the iris?
What is the primary effect of activating A1 receptors located in the radial dilator pupillae muscle of the iris?
What role does acetylcholine (ACh) play in pupil constriction?
What role does acetylcholine (ACh) play in pupil constriction?
What is the effect of contraction of the ciliary muscle on the lens of the eye?
What is the effect of contraction of the ciliary muscle on the lens of the eye?
In sympathetic activation, which physical changes occur due to pupil dilation?
In sympathetic activation, which physical changes occur due to pupil dilation?
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Which mechanism aids in fluid drainage from the eye and is important for the treatment of glaucoma?
Which mechanism aids in fluid drainage from the eye and is important for the treatment of glaucoma?
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What is the effect of sympathetic nervous system activation on the bladder?
What is the effect of sympathetic nervous system activation on the bladder?
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Which receptor does acetylcholine activate to promote bladder emptying?
Which receptor does acetylcholine activate to promote bladder emptying?
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What role does norepinephrine play in sympathetic bladder function?
What role does norepinephrine play in sympathetic bladder function?
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Which medication acts as an M3 antagonist to treat urinary frequency?
Which medication acts as an M3 antagonist to treat urinary frequency?
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What is the effect of prazosin on the bladder?
What is the effect of prazosin on the bladder?
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Under which circumstances would bethanechol be used?
Under which circumstances would bethanechol be used?
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How does sympathetic nervous system activation affect urination during perceived threats?
How does sympathetic nervous system activation affect urination during perceived threats?
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What dual action does norepinephrine have in the bladder during sympathetic activation?
What dual action does norepinephrine have in the bladder during sympathetic activation?
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What effect does sympathetic activation primarily have on vascular smooth muscle in the skin and gastrointestinal tract?
What effect does sympathetic activation primarily have on vascular smooth muscle in the skin and gastrointestinal tract?
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Which muscarinic receptor activation results in bronchoconstriction in the airways?
Which muscarinic receptor activation results in bronchoconstriction in the airways?
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What is the primary action of cholinesterase inhibitors like neostigmine in treating myasthenia gravis?
What is the primary action of cholinesterase inhibitors like neostigmine in treating myasthenia gravis?
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Which neurotransmitter's synthesis involves the enzyme tyrosine hydroxylase?
Which neurotransmitter's synthesis involves the enzyme tyrosine hydroxylase?
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How does the activation of M1 and M3 receptors affect glandular secretion?
How does the activation of M1 and M3 receptors affect glandular secretion?
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What mechanism does propanol, a sympatholytic drug, employ to affect the sympathetic nervous system?
What mechanism does propanol, a sympatholytic drug, employ to affect the sympathetic nervous system?
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What is the role of nitric oxide (NO) in the parasympathetic activation of blood vessels?
What is the role of nitric oxide (NO) in the parasympathetic activation of blood vessels?
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Which drug is an example of a sympathomimetic agent used as a decongestant?
Which drug is an example of a sympathomimetic agent used as a decongestant?
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Which process is primarily influenced by cholinergic signaling through M3 receptors in the digestive system?
Which process is primarily influenced by cholinergic signaling through M3 receptors in the digestive system?
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What is the main outcome of stimulation of beta-1 (B1) receptors in cardiac myocytes?
What is the main outcome of stimulation of beta-1 (B1) receptors in cardiac myocytes?
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Study Notes
Neuropharmacology Study Notes
- Neuropharmacology: The study of drugs that affect the nervous system.
ADRENALINE
- Secretion: A hormone released by the adrenal glands.
- Effects: Increases blood circulation, breathing, and carbohydrate metabolism.
- Function: Prepares muscles for exertion.
- Production: Produced exclusively by the medulla of the adrenal gland.
- Synthesis: Synthesized from noradrenaline.
- Chemical Composition: Contains a methyl group attached to its nitrogen.
- Receptor Activation: Activates both alpha and beta adrenergic receptors.
- Effects Summary: Increases heart rate and contractility, relaxes breathing tubes, increases blood pressure via vasoconstriction, and increases blood sugar levels.
NORADRENALINE
- Secretion: A hormone released by the adrenal medulla and sympathetic nerves.
- Function: Neurotransmitter and drug.
- Function as a drug: To raise blood pressure.
- Production: Produced by the medulla of the adrenal gland and the sympathetic nervous system.
- Synthesis: Synthesized from dopamine.
- Chemical Composition: Contains hydrogens attached to nitrogen.
- Receptor Activation: Activates alpha adrenergic receptors.
- Main Effect: Increasing blood pressure via vasoconstriction.
Synaptic Transmission
- Step 1: Action potential invades the presynaptic terminal.
- Step 2: Voltage-gated Ca²⁺ channels open and Ca²⁺ enters.
- Step 3: Synaptic vesicles move to the presynaptic membrane and fuse with it.
- Step 4: Neurotransmitter diffuses across the synaptic cleft.
- Step 5: Neurotransmitter binds to postsynaptic receptors.
- Step 6: Voltage-gated Na⁺ channels may be activated.
- GPCRs: Ligand-gated ion channels.
- Comment: This process is similar across many different types of neurons.
Neuronal Diversity - Neurotransmitter production and storage
-
GABAergic Neuron (inhibitory):
- Synthesis: Glutamate decarboxylase.
- Transporter: GABA transporter.
-
Noradrenergic Neuron (modulatory):
- Synthesis: Tyrosine hydroxylase, dopamine beta-hydroxylase.
- Transporter: Vesicular monoamine transporter.
- Transporter: Presynaptic catecholaminergic transporter (NET).
Neuronal Diversity - Postsynaptic responses
- Fast ionotropic actions: glutamate, GABA, acetylcholine, monoamines (most)
- Slow metabotropic actions: Ion channels, GPCRs, enzymes.
- Ionotropism: Muscle contraction.
- Dromotropism: Rate of conductance via AV node.
Drug Targets
- Voltage-gated Na⁺ channels: Blockers stop electrical transmission, local anesthetics and epilepsy treatment, experimental drug like tetrodotoxin.
- Voltage-gated Ca²⁺ channels: Blockers inhibit transmitter release.
Other Notes
- Exocytosis: Blocker inhibits transmitter release (e.g. Botulinum toxin A).
- Transmitter synthesis: Precursor of transmitter (e.g. dopamine) stimulates production.
- Vesicular storage: Blockers of vesicular transporter lead to empty vesicles.
- Presynaptic transmitter uptake: Blockers prolong transmitter actions (e.g. treatment of depression).
- Nicotinic AChRs: Pentameric structure. ACh binding sites, ionotropic receptors. Gq and Gi/o protein-coupled receptors.
- Drugs and the ANS: Parasympathomimetic, parasympatholytic, sympathomimetic, sympathetic.
- Heart, Parasympathetic activation: ACh activates M2 muscarinic receptors. Decrease in heart rate (negative chronotropic effect).
- Heart, Clinical applications: Atropine (non-selective muscarinic antagonist), Noradrenaline and adrenaline.
- Vasculature: Glyceryl trinitrate (GTN), Nitroglycerin.
- Airways: Parasympathetic activation, Sympathetic activation.
- Salbutamol/Salmeterol: B2-selective agonist, anti-asthmatic.
- Parasympathetic activation of digestive system: ACh activates M3 receptors.
- Clinical applications – ANS control of digestion: Pilocarpine, Bethanechol, Atropine, hyoscine. Pirenzepine
- Clinical applications – ANS control of bladder: Bethanechol, Darifenacin, Prazosin.
- Eye – pupil: Sympathetic activation.
- Clinical applications – ANS control of the pupil: Atropine, Tropicamide
- Clinical applications – ANS control of the eye: Carbachol, Pilocarpine, Atropine, Tropicamide, Timolol
- Indirectly acting parasympathomimetics: Clinical relevance of anticholinesterases.
- Indirectly acting sympatholytics: NA synthesis.
- Clinical applications of indirectly acting parasympatholysis: Botulinum toxin A.
- Tyramine: The 'cheese reaction', Amine contained in fermented foods, can act as sympathomimetic in patients on MAOIs.
- ADHD: Methylphenidate, common side effects, mechanism of action.
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Description
Explore the essential concepts of neuropharmacology, focusing on adrenaline and noradrenaline. This quiz covers their secretion, effects, functions, and mechanisms of action. Test your understanding of these critical hormones and their role in the nervous system.
