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Questions and Answers
Which type of adrenoceptors are primarily responsible for the fight-or-flight response in the sympathetic nervous system?
What is the main endogenous ligand for the adrenoceptors in the human body?
Which class of drugs directly activate adrenoceptors, leading to physiological responses similar to those of the sympathetic nervous system?
Which neurotransmitter is primarily associated with dopaminergic receptors in the brain and peripheral nervous system?
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What is the primary mechanism of action for sympathomimetic drugs acting indirectly?
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Which of the following drugs is classified as a non-selective α1, α2, β1, and β2 agonist?
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Which of the following is a potential side effect of β2-selective sympathomimetic drugs like salbutamol?
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Which of the following drugs is classified as a selective α2 agonist?
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Which of the following neurotransmitters is classified as a D1, D2, and β1 agonist?
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Which of the following drugs is classified as a selective β1 agonist?
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Which of the following is a potential side effect of α1-selective sympathomimetic drugs like phenylephrine?
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Which adrenergic receptor is adrenaline (epinephrine) NOT an agonist on?
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What is a potential severe adverse effect of adrenaline (epinephrine) administration?
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Which medication is used for the treatment of anaphylactic shock through local vasoconstriction?
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Which neurotransmitter acts as a precursor for adrenaline and noradrenaline?
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What is a potential adverse effect associated with prolonged infusion of dopamine?
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Which adrenergic receptor is not directly activated by Noradrenaline (Norepinephrine)?
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In addition to its cardiovascular effects, what other effect is produced by Noradrenaline (Norepinephrine)?
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What is the primary effect of Dobutamine on the cardiovascular system?
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Which of the following effects is not associated with Salbutamol?
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What type of drug inhibits the reuptake of norepinephrine and dopamine?
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Study Notes
Introduction to Sympathetic Nervous System (SNS)
- The sympathetic nervous system (SNS) is a part of the autonomic nervous system (ANS)
- The SNS is responsible for the "fight or flight" response
- The SNS is controlled by adrenergic receptors (adrenoceptors)
Adrenergic Receptors (Adrenoceptors)
- Adrenoceptors are G-protein coupled receptors (GPCR)
- There are two main types of adrenoceptors: alpha (α) and beta (β)
- Alpha receptors are further divided into α1 and α2, while beta receptors are divided into β1, β2, and β3
- Dopamine receptors are also involved in the SNS and are divided into D1 and D2
Sympathomimetics: Direct Acting
- Sympathomimetics are drugs that mimic the effects of endogenous ligands on the SNS
- Direct acting sympathomimetics are classified into non-selective, selective, and mixed acting
- Non-selective sympathomimetics include adrenaline (α1, α2, β1, β2), noradrenaline (α1, α2, β1), and dopamine (D1, D2, β1)
- Selective sympathomimetics include phenylephrine (α1), clonidine (α2), dobutamine (β1), and salbutamol (β2)
Sympathomimetics: Indirect Acting
- Indirect acting sympathomimetics include releasing agents, catecholamine reuptake inhibitors, and MAO/COMT inhibitors
- Releasing agents, such as amphetamine, stimulate the release of catecholamines from storage vesicles
- Catecholamine reuptake inhibitors, such as amitriptyline, block the reuptake of noradrenaline from the synapse
- MAO/COMT inhibitors, such as phenelzine and selegiline, inhibit the metabolism of catecholamines
Sympathomimetics: Mixed Acting
- Mixed acting sympathomimetics, such as ephedrine, indirectly release noradrenaline and directly activate adrenoceptors (α1, α2, β1, β2)
- Ephedrine is absorbed well orally and has a long duration of action
- Ephedrine is excreted unchanged in the urine
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Description
Learn about the classifications and actions of sympathomimetic drugs that mimic the effects of endogenous ligands on the sympathetic nervous system. Explore the distinctions between non-selective and selective direct-acting sympathomimetics.
