Questions and Answers
What two systems primarily make up the autonomic nervous system?
Which of the following processes is regulated primarily by the autonomic nervous system?
The sympathetic nervous system is best associated with which response?
Which system is primarily responsible for conveying output from the central nervous system (CNS) to the body?
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Which of the following correctly identifies one of the roles of the autonomic nervous system?
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Which component is NOT part of the autonomic nervous system?
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What is a common side effect associated with the use of Doxazosin?
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Which of the following is NOT a mechanism by which β-blockers lower arterial blood pressure?
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Which β-blocker is considered non-selective, affecting both a1 and β receptors?
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What is one common clinical use for β1-subtype selective (cardioselective) β-blockers?
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Which of the following β-blockers is identified as cardioselective?
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Which mechanism is NOT typically associated with the effects of β-blockers on blood pressure?
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What is the termination process of noradrenergic signaling based on?
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Which one of the following is a side effect associated with β-blockers?
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What is the primary effect of α-methyl-tyrosine in the sympathetic nervous system?
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Which pharmacological agent prevents the storage of noradrenaline in vesicles?
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What is the role of presynaptic α2 adrenoreceptors in neurotransmitter release?
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Which structure is primarily involved in the stimulation of PLC by α1 adrenergic receptors?
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What cellular response occurs when β1 adrenergic receptors are activated?
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What is the primary action of α-blockers in the sympathetic nervous system?
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What is a notable side effect of reserpine administration?
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What distinguishes the efficacy of α2 adrenergic receptors from α1 adrenergic receptors?
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Which adrenergic receptor type is primarily associated with smooth muscle relaxation?
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Which of the following best describes the consequence of activating Gi proteins in autoreceptors?
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Which mechanism involves the direct absorption of neurotransmitters back into the presynaptic terminal?
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What is the consequence of taking MAO inhibitors in regard to tyrosine metabolism?
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Which of the following drugs is an irreversible non-selective MAO inhibitor?
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Salbutamol primarily targets which receptor subtype?
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Which drug is known to selectively inhibit MAO-B and is often used in Parkinson's Disease?
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What is the main risk of consuming cheese while taking MAO inhibitors?
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Which of the following statements best describes a common feature of drugs targeted for synaptic transmission?
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Doxazosin is primarily classified as which type of drug?
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What is the primary neurotransmitter involved in the functions of the sympathetic nervous system?
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Which of the following is NOT a function associated with increased sympathetic activity?
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During the electrochemical signaling at a noradrenergic synapse, which step occurs immediately after the depolarization of the presynaptic terminal?
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Which of the following processes best describes the decrease in gastrointestinal function associated with sympathetic activation?
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Which of the following components is involved in the signal termination of noradrenaline activity?
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What effect does activation of post-synaptic adrenergic receptors have on the cell?
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Which physiological response is directly linked to vasoconstriction during sympathetic activation?
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What is the function of voltage-gated Ca2+ channels in noradrenaline signaling?
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Study Notes
Autonomic Nervous System Overview
- Composed of the somatic nervous system and autonomic nervous system (ANS).
- ANS includes the sympathetic (adrenergic) and parasympathetic (cholinergic) branches.
- Functions to transmit outputs from the central nervous system (CNS) to the body excluding skeletal muscle control, which is somatic.
Main Functions of the Autonomic Nervous System
- Controls contraction and relaxation of smooth muscle.
- Regulates exocrine and some endocrine secretions.
- Manages heartbeat, affecting force and rate of contraction.
- Influences energy metabolism.
Sympathetic Nervous System
- Associated with the "fight or flight" response.
- Increases heart rate and cardiac muscle contraction.
- Facilitates bronchodilation, enabling easier airflow.
- Promotes gluconeogenesis for energy production.
- Causes pupil dilation and decreases gastrointestinal (GI) function.
- Mediates vasoconstriction.
- Primary neurotransmitter is noradrenaline.
Drug Intervention Opportunities
- Focuses on noradrenergic synaptic signaling, including synthesis and release of noradrenaline.
- Basic sequence includes synthesis, storage, depolarization, release, receptor activation, and termination of signals.
Noradrenaline Synthesis
- Inhibited by α-methyl-tyrosine, which blocks tyrosine hydroxylase.
- Use includes reducing blood pressure with side effects such as sedation and diarrhea.
Noradrenaline Storage
- Vulnerable to breakdown by monoamine oxidase (MAO) if not stored in vesicles via vesicular monoamine transporter (VMAT).
- Reserpine can pharmacologically target VMAT leading to noradrenaline depletion.
Neurotransmitter Release
- Regulated by negative feedback through autoreceptors (e.g., α2 adrenoreceptors).
- Autoreceptor stimulation can inhibit neurotransmitter release.
- Clonidine, a selective α2 agonist, is used to decrease neurotransmitter release.
Adrenergic Receptor Activation
- All neurotransmitters work as agonists at their respective receptors, essential for signaling.
- Governs affinitive binding and efficacy – the capacity to activate receptors post-binding.
G-Protein Coupled Receptors (GPCRs)
- Comprising seven transmembrane domains; activation leads to GTP/GDP exchange.
- Gs, Gq, and Gi represent the three main G proteins, with diverse effects on signaling pathways.
α1 and α2 Adrenergic Receptors
-
α1 Receptors:
- GPCRs coupled with Gq, prevalent in post-synaptic smooth muscle, activate phospholipase C (PLC), causing contraction and secretion.
-
α2 Receptors:
- GPCRs coupled with Gi, mainly found at presynaptic terminals, inhibit adenylyl cyclase and noradrenaline release.
β1 and β2 Adrenergic Receptors
-
β1 Receptors:
- Predominantly in cardiac muscle, stimulate adenylyl cyclase leading to increased contraction force and heart rate.
-
β2 Receptors:
- Present in bronchial and skeletal muscle, promote smooth muscle relaxation by stimulating adenylyl cyclase.
Adrenergic Receptor Antagonists
-
α-blockers:
- Lower blood pressure by blocking sympathetic-induced vasoconstriction; includes non-selective (e.g., Phenoxybenzamine) and selective blockers (e.g., Doxazosin).
-
β-blockers:
- Reduce blood pressure by blocking β receptors; utilized in cardiac conditions. Includes non-selective (Propanolol) and selective (Atenolol) options.
Neurotransmitter Termination Mechanisms
- Occurs via diffusion from the synapse, reuptake into the presynaptic terminal, or enzymatic degradation by MAO.
- MAO inhibitors (e.g., Phenelzine, Moclobemide) can lead to potential hypertensive crises when consuming tyramine-rich foods.
Drug Targeting and Therapeutics
- Emphasizes selectivity in drug action to minimize side effects.
- Examples of selective drugs include Salbutamol (β2 agonist), Atenolol (β1 antagonist), and Doxazosin (α1 antagonist).
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Description
Explore the key components and functions of the Autonomic Nervous System (ANS), including its sympathetic and parasympathetic branches. This quiz covers its role in regulating internal bodily functions separate from the skeletal muscle control managed by the somatic nervous system.
