Autonomic Nervous System Overview
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Questions and Answers

What is the primary function of the sympathetic nervous system?

  • Increase digestive activity
  • Fight or flight (correct)
  • Promote relaxation
  • Rest and digest

Which neurotransmitter is released by the postganglionic neurons of the sympathetic nervous system?

  • Norepinephrine (correct)
  • Serotonin
  • Epinephrine
  • Acetylcholine

How do preganglionic neurons differ between the sympathetic and parasympathetic nervous systems?

  • Both release norepinephrine
  • Parasympathetic has shorter preganglionic neurons
  • Sympathetic has longer preganglionic neurons
  • Sympathetic has shorter preganglionic neurons (correct)

What type of muscle control is primarily regulated by the autonomic nervous system?

<p>Smooth muscle control (A)</p> Signup and view all the answers

What occurs at the synapse between two neurons?

<p>Neurotransmitters are released and bind to receptors (A)</p> Signup and view all the answers

What is the primary function of postganglionic neurons in the peripheral nervous system?

<p>Sending signals to the target organ (B)</p> Signup and view all the answers

What role do catecholamines play in the sympathetic nervous system?

<p>Support the fight or flight response (C)</p> Signup and view all the answers

Which of the following is an alpha 1 receptor agonist used as a nasal decongestant?

<p>Phenylephrine (B)</p> Signup and view all the answers

How does an alpha 2 agonist like clonidine affect blood pressure?

<p>Decreases blood pressure (A)</p> Signup and view all the answers

Which receptor is primarily found in the heart and is targeted by beta 1 agonists?

<p>Beta 1 receptor (D)</p> Signup and view all the answers

What is a major effect of beta 2 receptor agonists like albuterol?

<p>Bronchodilation (D)</p> Signup and view all the answers

What is the action of an antagonist on receptors?

<p>Blocks the receptor from responding (A)</p> Signup and view all the answers

What is a potential side effect of anticholinergic medications?

<p>Urinary retention (B)</p> Signup and view all the answers

Which drug is considered a non-depolarizing neuromuscular blocking agent?

<p>Rocuronium (B)</p> Signup and view all the answers

What kind of medication is procaine, considering it is an alpha 1 antagonist?

<p>Antihypertensive (D)</p> Signup and view all the answers

What neurotransmitter is primarily associated with the actions of the sympathetic nervous system?

<p>Norepinephrine (C)</p> Signup and view all the answers

Which of the following statements describes the primary role of muscarinic receptors?

<p>Mediates parasympathetic responses (B)</p> Signup and view all the answers

What is the effect of a muscarinic agonist like pilocarpine?

<p>Decreases intraocular pressure (D)</p> Signup and view all the answers

Which of the following is NOT a function of the hypothalamus related to autonomic control?

<p>Controls voluntary muscle movements (B)</p> Signup and view all the answers

Which of the following accurately describes the characteristics of the sympathetic nervous system?

<p>Short preganglionic fibers and long postganglionic fibers (C)</p> Signup and view all the answers

What is the main role of the autonomic nervous system?

<p>To regulate functions without conscious thought (D)</p> Signup and view all the answers

Which neurotransmitter is released by the postganglionic neurons in the parasympathetic nervous system?

<p>Acetylcholine (D)</p> Signup and view all the answers

Which statement best describes the adrenal medulla's role in the sympathetic nervous system?

<p>It acts as a postganglionic neuron without a prior synapse (B)</p> Signup and view all the answers

What occurs at the synapse between two neurons in the nervous system?

<p>Release of neurotransmitters to facilitate communication (B)</p> Signup and view all the answers

What is the primary effect of an alpha 1 antagonist?

<p>Decrease blood pressure (B)</p> Signup and view all the answers

The hypothalamus is primarily responsible for what aspect of autonomic control?

<p>Integration of emotional stress and autonomic responses (C)</p> Signup and view all the answers

Which of the following is a characteristic of norepinephrine release?

<p>Can interact with multiple receptors including alpha and beta (D)</p> Signup and view all the answers

What is the primary use of dobutamine in clinical settings?

<p>To treat acute decompensated heart failure (C)</p> Signup and view all the answers

What distinguishes muscarinic receptors from nicotinic receptors in relation to acetylcholine?

<p>Muscarinic receptors have a higher affinity for acetylcholine at lower doses. (B)</p> Signup and view all the answers

Which statement about beta 2 receptor agonists is incorrect?

<p>They primarily target vascular smooth muscle. (A)</p> Signup and view all the answers

What role do cholinergic receptors play in the parasympathetic nervous system?

<p>They mediate 'rest and digest' activities by responding to acetylcholine. (B)</p> Signup and view all the answers

What is a function of the alpha 2 receptor?

<p>Inhibit the release of norepinephrine (D)</p> Signup and view all the answers

Which of the following represents a non-selective alpha receptor antagonist?

<p>Phentolamine (C)</p> Signup and view all the answers

Which medication serves as a neuromuscular blocking agent that causes flaccid paralysis?

<p>Succinylcholine (D)</p> Signup and view all the answers

Which effect is associated with the administration of an anticholinergic drug?

<p>Urinary retention (C)</p> Signup and view all the answers

How does an antagonist function at a receptor level?

<p>It blocks the ligand binding and prevents a response. (D)</p> Signup and view all the answers

Which statement accurately describes endogenous ligands?

<p>They include neurotransmitters naturally occurring in the body. (A)</p> Signup and view all the answers

Flashcards

Sympathetic Nervous System

Part of the autonomic nervous system, responsible for 'fight or flight' responses.

Parasympathetic Nervous System

Part of the autonomic nervous system, responsible for 'rest and digest' functions.

Autonomic Nervous System

System of nerves that controls involuntary functions; like organs and glands.

Synapse

Gap between neurons where neurotransmitters transmit signals.

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Neurotransmitters

Chemical messengers that transmit signals across synapses.

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Preganglionic neuron

A neuron in the central nervous system (CNS) that transmits signals to a ganglion.

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Postganglionic neuron

A neuron in the peripheral nervous system that transmits signals from a ganglion to a target organ.

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Hypothalamus

The command center for autonomic control; stress impacts it.

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Parasympathetic vs. Sympathetic

Two branches of the autonomic nervous system with opposing effects.

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Neurotransmitter reuptake

Process of neurotransmitters being taken back into the terminal button. This process is used whenever storage is required.

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Acetylcholine (ACh)

A major neurotransmitter in the parasympathetic nervous system.

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Catecholamines

Neurotransmitters (NE, EPI, Dopamine) associated with the sympathetic nervous system 'fight-or-flight' response

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Alpha 1 receptor

A type of adrenergic receptor found in smooth muscle, such as blood vessels, eyes, and bladder.

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Alpha 2 receptor

A type of adrenergic receptor found on the presynaptic neuron; it inhibits NE release.

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Beta 1 receptor

A type of adrenergic receptor found in the heart.

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Beta 2 receptor

A type of adrenergic receptor found in the lungs; important for bronchodilation.

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Alpha 1 agonist

A drug that activates alpha 1 receptors, increasing blood pressure and causing smooth muscle contraction.

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Alpha 1 antagonist

A drug that blocks alpha 1 receptors, decreasing blood pressure and relaxing smooth muscle.

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Muscarinic receptor

A type of cholinergic receptor, activated by ACh; affects various organs.

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What is the function of the autonomic nervous system?

The autonomic nervous system controls involuntary bodily functions, like heart rate, digestion, and breathing, without conscious effort.

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What is the difference between sympathetic and parasympathetic?

Sympathetic is 'fight or flight', increasing heart rate and preparing for action. Parasympathetic is 'rest and digest', calming the body and promoting relaxation.

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What are the preganglionic and postganglionic neurons?

Preganglionic neurons are in the CNS and send signals to ganglia. Postganglionic neurons are in the PNS and relay signals to target organs.

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What is a synapse?

A synapse is the tiny gap between neurons where neurotransmitters are released and bind to receptors.

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What is the role of neurotransmitters?

Neurotransmitters are chemical messengers that transmit signals across synapses, influencing various bodily functions.

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What does 'endogenous' mean in relation to ligands?

Endogenous ligands are naturally occurring substances within the body that bind to receptors.

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What is a ligand?

A ligand is a molecule that binds to a receptor, but not always causing an effect.

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What are adrenergic receptors?

Adrenergic receptors are a type of receptor that are activated by catecholamines, such as norepinephrine and epinephrine.

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What do Alpha 1 receptors do?

Alpha 1 receptors primarily cause constriction of smooth muscle in blood vessels, eyes, and bladder.

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What is the effect of an Alpha 1 agonist?

An Alpha 1 agonist activates Alpha 1 receptors, leading to increased blood pressure, pupillary dilation, and bladder relaxation.

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What do Alpha 2 receptors do?

Alpha 2 receptors are located on the presynaptic neuron and inhibit the release of norepinephrine.

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What is the effect of an Alpha 2 agonist?

An Alpha 2 agonist activates Alpha 2 receptors, reducing blood pressure.

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What does an antagonist do to a receptor?

An antagonist binds to a receptor but blocks its activation, preventing any response.

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What do Beta 1 receptors do?

Beta 1 receptors are found primarily in the heart and increase heart rate.

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What do Beta 2 receptors do?

Beta 2 receptors are mainly found in the lungs and stimulate bronchodilation, opening up the airways.

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How do non-selective alpha blockers work?

Non-selective alpha blockers interact with both Alpha 1 and Alpha 2 receptors, affecting various bodily functions.

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What is a cholinergic receptor?

A cholinergic receptor is a type of receptor that is activated by acetylcholine, a neurotransmitter in the parasympathetic nervous system.

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What is the difference between muscarinic and nicotinic receptors?

Muscarinic receptors are activated by ACh at lower doses, while nicotinic receptors are activated at higher doses.

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What is the effect of an anticholinergic drug?

Anticholinergic drugs block the effects of acetylcholine, reducing parasympathetic activity.

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What are neuromuscular blocking agents used for?

Neuromuscular blocking agents are used to paralyze muscles, primarily during surgery.

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Study Notes

Autonomic Nervous System

  • The autonomic nervous system (ANS) regulates involuntary functions, including smooth muscle in organs.
  • The ANS is divided into two branches: sympathetic and parasympathetic.

Sympathetic Nervous System

  • Function: "Fight or flight" response.
  • Preganglionic neurons: Short axons.
  • Postganglionic neurons: Long axons.
  • Neurotransmitters:
    • Preganglionic: Acetylcholine (Ach).
    • Postganglionic: Norepinephrine (NE).
    • Adrenal medulla (part of the sympathetic system): Releases NE (adrenaline) directly into the bloodstream; it lacks a postganglionic neuron.
  • Effects:
    • Blood vessel control (vasodilation and vasoconstriction).
    • Sweat gland stimulation (Ach).

Parasympathetic Nervous System

  • Function: "Rest and digest" response.
  • Preganglionic neurons: Long axons.
  • Postganglionic neurons: Short axons.
  • Location: Located closer to target organs (spinal cord).
  • Neurotransmitters:
    • Preganglionic: Acetylcholine (Ach).
    • Postganglionic: Acetylcholine (Ach).

Synapses

  • Synapse: The gap between neurons where neurotransmitters are released and bind to receptors.
  • Preganglionic neurons reside in the CNS.
  • Postganglionic neurons are in the PNS and control target organs.
  • The hypothalamus is the central control center for autonomic functions; stress impacts it.

Neurotransmitter Actions in the ANS

  • Neurotransmitters are stored and released at synapses.
  • Acetylcholinesterase (AchE) breaks down Ach.
  • Catecholamines: NE, dopamine, and epinephrine (adrenaline) are released during "fight or flight."
  • Catecholamines are released from the hypothalamus.
  • Cholinergic receptors: Muscarinic and nicotinic receptors respond to Ach.
    • Nicotinic receptors respond to nicotine.

Sympathetic Agents

  • Endogenous ligands: The naturally occurring substances that bind to receptors. Catecholamines (NE, EPI, and dopamine).
  • Ligands: Substances that bind to receptors.
  • Adrenergic receptors: Alpha and beta receptors.
  • Alpha 1 receptors: Location: Smooth muscle (vessels, eyes, bladder); Effect: Smooth muscle contraction.
  • Alpha 2 receptors: Location: Presynaptic neuron; Effect: Decreased NE release.
  • Beta 1 receptors: Location: Heart; Effect: Increased heart rate.
  • Beta 2 receptors: Location: Lungs; Effect: Bronchodilation.
  • NE effects: NE acts on different receptors in different organs (different effects). Alpha 1 receptors in heart alters blood pressure.
  • Agonists: Mimic the action of a neurotransmitter.
  • Antagonists: Block the action of a neurotransmitter.

Alpha Receptors

  • Alpha 1 agonist: Phenylephrine (nasal decongestant), Increases blood pressure, dilation of eyes, relax bladder, contract prostate.
  • Alpha 1 antagonist: Prazosin (treats hypertension and benign prostatic hyperplasia (BPH)).
  • Alpha 2 agonist: Clonidine (treats hypertension).
  • Alpha 2 antagonist: Yohimbine (treats male dysfunction).
  • Non-selective Alpha receptor blockers: Phenoxybenzamine, Phentolamine (treats hypertension/sweating).

Beta Receptors

  • Beta 1 agonist: Dobutamine (treats acute decompensated heart failure).
  • Beta 1 antagonist: Metoprolol, Atenolol (treats hypertension, angina, MI, and heart failure). Beta blocker selectivity important to avoid respiratory suppression.
  • Beta 2 agonist: Albuterol (short-acting bronchodilator), Salmeterol (long-acting bronchodilator).
  • Non-selective beta blockers: Propranolol, Labetalol (treats hypertension, angina, MI, cardiac dysrhythmias/ migraine prevention (propranolol)).

Parasympathetic Agents

  • Cholinergic receptors: Muscarinic and nicotinic receptors, respond to Ach. Ach has higher affinity for muscarinic at low doses, higher doses= nicotinic
  • Muscarinic agonists: Carbachol (glaucoma), Pilocarpine (dry mouth).
  • Nicotinic agonist: Varenicline (tobacco dependence treatment).
  • Antimuscarinics (anticholinergics): Block parasympathetic effects.
    • Adverse effects: urinary retention.
    • Examples: Atropine (reduces salivation and respiratory tract secretions for surgery), Oxybutynin (overactive bladder), Dicyclomine (IBS).

Neuromuscular Blocking Agents

  • Succinylcholine: Depolarizing agent; inhibits repolarization causing persistent depolarization of the motor end plate leading to flaccid paralysis.
  • Non-depolarizing agents (NMBA): Antagonists; block muscle contraction.
    • Examples: Rocuronium, Atracurium.
  • Reversal agents for NMBA: Neostigmine (acetylcholinesterase inhibitor), Sugammadex (for steroidal NMBA).

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Explore the complexities of the autonomic nervous system in this quiz. Learn about its two branches, the sympathetic and parasympathetic systems, and their respective functions, neurotransmitters, and effects on the body. Test your knowledge on how these systems regulate involuntary functions.

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