Autonomic Nervous System Overview
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Questions and Answers

What is the primary function of alpha-2 adrenergic receptors in the sympathetic nervous system?

  • Stimulating norepinephrine release
  • Increasing heart rate
  • Inhibiting presynaptic norepinephrine release (correct)
  • Causing contraction of smooth muscles

    • Which physiological effect is primarily associated with beta-1 adrenergic receptors?

  • Relaxation of the GI tract
  • Increased heart rate and contractility (correct)
  • Vasodilation in skeletal muscles
  • Bronchodilation

    • What effect do beta-2 adrenergic receptors have on smooth muscles?

  • Inhibition of heart rate
  • Contraction of the bladder
  • Increase in blood pressure
  • Bronchodilation and relaxation of walls in various organs (correct)

    • Which of the following statements is true regarding beta-1 adrenergic receptors in the kidney?

    <p>They stimulate renin release.</p> Signup and view all the answers

    What second messenger system is activated by beta-1 adrenergic receptors?

    <p>cAMP</p> Signup and view all the answers

    What effect does a muscarinic agonist have on the heart?

    <p>Decreased heart rate and contraction</p> Signup and view all the answers

    What happens to the sphincters under a parasympathetic response?

    <p>They relax</p> Signup and view all the answers

    What is the effect of stimulating M3 receptors in the bladder wall?

    <p>Contraction of the bladder wall</p> Signup and view all the answers

    Which of the following statements about irreversible cholinesterase inhibitors is true?

    <p>They can be used as poisonous gases in warfare</p> Signup and view all the answers

    What is the outcome of an excessive cholinergic response regarding secretions?

    <p>Increased secretions including salivary and respiratory</p> Signup and view all the answers

    How does a muscarinic agonist affect the lungs?

    <p>Bronchoconstriction</p> Signup and view all the answers

    What is the role of M receptors in the CNS?

    <p>They are involved in cognitive function</p> Signup and view all the answers

    Which process is characterized by no recovery when cholinesterase is bound?

    <p>Phosphorylation</p> Signup and view all the answers

    Which receptors are classified as cholinergic?

    <p>Nicotinic and Muscarinic</p> Signup and view all the answers

    What is the primary neurotransmitter released at the ganglia in both the sympathetic and parasympathetic nervous systems?

    <p>Acetylcholine</p> Signup and view all the answers

    What regions of the spinal cord do the parasympathetic nerves originate from?

    <p>Craniosacral</p> Signup and view all the answers

    Which neurotransmitter is synthesized from tyrosine?

    <p>Norepinephrine</p> Signup and view all the answers

    The two types of adrenergic receptors are categorized into which subtypes?

    <p>Alpha and Beta</p> Signup and view all the answers

    Which muscarinic receptors are G-protein coupled to Gi and influence heart rate?

    <p>M2 and M4</p> Signup and view all the answers

    What is the dominant neurotransmitter released by the adrenal medulla?

    <p>Epinephrine</p> Signup and view all the answers

    How many subdivisions are there for muscarinic receptors?

    <p>Five</p> Signup and view all the answers

    Which of the following statements about the PSNS is incorrect?

    <p>Receptors are referred to as adrenergic.</p> Signup and view all the answers

    Which action characterizes the effects of a muscarinic agonist?

    <p>Opposes adrenergic agonist effects</p> Signup and view all the answers

    What is the primary effect of beta-2 adrenergic receptors in the bladder wall?

    <p>Relaxation of the bladder wall</p> Signup and view all the answers

    Which of the following processes are mediated by beta-2 receptors in the liver?

    <p>Gluconeogenesis</p> Signup and view all the answers

    How do sympathomimetics primarily act on adrenergic receptors?

    <p>By directly activating adrenergic receptors or increasing neurotransmitter levels</p> Signup and view all the answers

    What is the effect of alpha-1 adrenergic receptors in the sphincter?

    <p>Induce contraction</p> Signup and view all the answers

    What happens when neurotransmitter reuptake is inhibited in the synapse?

    <p>Increased neurotransmitter concentration</p> Signup and view all the answers

    Which of the following actions is NOT a method to increase neurotransmitter levels in the synapse?

    <p>Decreasing synaptic cleft size</p> Signup and view all the answers

    What role does adenylate cyclase play in G-protein coupled receptor signaling?

    <p>Converts ATP to cAMP</p> Signup and view all the answers

    What type of receptor does the new compound act as an agonist for regarding skeletal muscle blood vessel relaxation?

    <p>Beta-2 receptor</p> Signup and view all the answers

    Which organ systems are primarily innervated by the sympathetic nervous system?

    <p>Liver, kidney, and uterus</p> Signup and view all the answers

    Which physiological effect is associated with the activation of M3 receptors in the bladder wall?

    <p>Contraction of the bladder wall</p> Signup and view all the answers

    What physiological response does the compound produce in bronchodilation?

    <p>Activation of beta-2 receptors</p> Signup and view all the answers

    What receptor mediation causes relaxation of the bladder wall according to the autonomic nervous system?

    <p>M3 receptors</p> Signup and view all the answers

    Which type of receptor is minimally involved in the relaxation of skeletal muscle vessels?

    <p>Alpha-2 receptors</p> Signup and view all the answers

    What is the net effect of the sympathetic nervous system on the bladder?

    <p>Inhibits urination</p> Signup and view all the answers

    Which receptor type causes vasoconstriction in the circulatory system?

    <p>Alpha-1 receptors</p> Signup and view all the answers

    What receptor does the sympathetic nervous system primarily activate to achieve relaxation of the bladder wall?

    <p>Beta-2 receptors</p> Signup and view all the answers

    Study Notes

    Nomenclature

    • The Parasympathetic Nervous System (PSNS) is also called:
      • Cholinergic
      • Muscarinic
    • The Sympathetic Nervous System (SNS) is also called:
      • Adrenergic

    Anatomy

    • PSNS Nerves (Craniosacral):
      • Originate from the top and bottom of the spinal cord
    • SNS Nerves (Thoracolumbar):
      • Originate from the middle of the spinal cord

    ANS Anatomy

    • The SNS and PSNS both have ganglia
    • The neurotransmitter released at the ganglia is acetylcholine (ACh)
    • The receptors in the ganglia are nicotinic receptors

    Neurotransmitters (NT)

    • Acetylcholine is synthesized from Acetyl CoA and Choline
    • Acetylcholine is stored in synaptic vesicles

    ANS Anatomy - The Adrenal Medulla:

    • The adrenal medulla is source of NT, releasing 80% epinephrine (Epi) and 20% norepinephrine (NE)

    Neurotransmitters (NT): Synthesis

    • Key NT like dopamine, norepinephrine, and epinephrine are synthesized from tyrosine
    • The catecholamines (dopamine, norepinephrine, epinephrine) are a type of NT synthesized from tyrosine

    Receptor Distribution: Cholinergic

    • There are two types of cholinergic receptors: Nicotinic and Muscarinic
    • Nicotinic receptors are found in:
      • Muscle
      • Ganglia
      • Adrenal Medulla
      • Central Nervous System (CNS)
      • Immune System
    • Muscarinic receptors are divided into 5 subtypes:
      • M1, M3, M5: G-protein coupled (Gq)
      • M2, M4: G-protein coupled (Gi)

    PSNS-Receptors

    • PSNS Receptors are referred to as Muscarinic (M)
    • Most drugs targeting M receptors are not classified by subtype
    • Fewer drugs target M receptors than adrenergic receptors
    • M receptors play an important role in drug side effects

    M1, M3, M5 Receptors

    • G-protein coupled (Gq)
    • Found in:
      • Smooth Muscle:
        • Contraction
      • Bladder:
        • Contraction

    M2, M4 Receptors

    • G-protein coupled (Gi)
    • Found in:
      • Heart:
        • Decreased rate, contraction
        • Decreased heart rate

    PSNS-Receptors

    • The effects of muscarinic agonists oppose the effects of adrenergic agonists
    • Effects of muscarinic agonists:
      • Heart:
        • Decreased rate
        • Decreased contraction
      • Lungs:
        • Bronchoconstriction
      • Sphincters (GI and bladder):
        • Relaxation
      • Walls:
        • Contraction of bladder and GI tract walls

    To Pee or Not to Pee - Bladder and Urination

    • PSNS response in the bladder:
      • M3 in bladder wall: contracts
      • M3 in sphincter: relaxes
      • This results in urination

    PSNS-Receptors

    • Increased secretion:
      • Salivary
      • Respiratory
      • Tears
    • Eye: (more on this later)

    PSNS-Receptors

    • M receptors play an important role in CNS
    • M Receptors are important for cognitive function

    Ligands for Muscarinic Receptors

    • Direct stimulation:
      • Use of an agonist
    • Indirect stimulation:
      • Acetylcholinesterase inhibitors increase the concentration of acetylcholine

    Indirect-Acting Cholinergic Drugs

    • Cholinesterase can bind to 3 types:
      • Acetylation:
        • Rapid Recovery
        • Physiological
      • Carbamylation:
        • Slower Recovery
        • Reversible drugs (e.g., neostigmine)
      • Phosphorylation:
        • No recovery
        • Irreversible drugs (e.g., "nerve gases")

    Indirect-Acting Cholinergic Drugs:

    • Irreversible cholinesterase inhibitors have been used in chemical warfare

    Excess Cholinergic Response

    • Excessive cholinergic response can cause:
      • Excessive secretion
      • Other related side-effects

    Alpha-1 Adrenergic Receptors

    • G-protein coupled (Gq)
    • Causes contraction

    Sympathetic Nervous System (SNS)

    • Alpha-2 (α-2)
      • Function: inhibits the release of norepinephrine

    Alpha-2 Agonists

    • Binding of alpha-2 receptor agonist:
      • Inhibits the release of norepinephrine

    Sympathetic Nervous System (SNS)

    • Beta-1 (β-1)
      • Function: stimulates the heart
      • Location:
        • Heart:
          • Increased heart rate
          • Increased atrioventricular conduction
          • Increased contractility

    Beta-1 Adrenergic Receptors

    • G-protein coupled (Gs)
    • Found in:
      • Heart:
        • Increased heart rate
        • Increased contractility

    Beta-1 Adrenergic Receptors

    • Liver, kidney, and uterus are innervated by the SNS
    • Kidney:
      • Beta-1 receptors stimulate renin release
      • Renin causes increased blood pressure

    Beta-2 Adrenergic Receptors

    • Function: relaxation of smooth muscle
    • Location:
      • Lungs: Bronchodilation
      • Blood vessels in skeletal muscle: Vasodilation
      • GI tract, bladder, uterus: relaxation of walls

    Beta-2 Adrenergic Receptors

    • G-protein coupled (Gs)
    • Found in:
      • Lungs: Bronchodilation

    To Pee or Not to Pee - Bladder & Urination

    • SNS response in the bladder:
      • β-2 in bladder wall: relaxes
      • α-1 in sphincter: contracts
      • This results in not urinating

    Beta-2 Adrenergic Receptors

    • Liver, kidney, and uterus innervated by the SNS
    • Liver:
      • Beta-2 receptors mediate glucose release by:
        • Gluconeogenesis: formation of new glucose
        • Glycogenolysis: breakdown of glycogen to glucose

    Ligands for Adrenergic Receptors

    • Sympathomimetics mimic stimulation of the SNS:
      • Direct activation of adrenergic receptors
      • Increased NT in the synapse

    Sympathomimetics

    • Increasing NT in the synapse by:
      • Increasing neurotransmitter release
      • Inhibiting reuptake of neurotransmitter

    Fate of Neurotransmitters

    • Reuptake pumps sit presynaptically, remove neurotransmitters from the synapse

    Sympathomimetics

    • Inhibiting neurotransmitter reuptake increases the amount of NT in the synapse

    Sympathomimetics

    • Increasing NT in the synapse:
      • Inhibiting neurotransmitter reuptake is more effective
      • Muscarinic antagonists can also be used
      • Beta-2 agonists can also be used, but have minimal effect

    Case #2

    • A compound causes the following:
      • Skeletal muscle vessels to relax
      • Uterus relaxation
      • Bronchodilation
    • This compound is likely a beta-2 agonist

    ANS effects in the circulation (Summary/Review)

    • SNS:
      • β-2 receptors (skeletal muscle): Vasodilation
      • α-1 receptors: Vasoconstriction
    • PSNS:
      • Minimal contribution to circulation
      • Stimulation of M3 causes nitric oxide release, leading to vasodilation

    Case #2

    • A compound causes the following:
      • Skeletal muscle vessels to relax
      • Bladder wall relaxation
      • Bronchodilation
    • This compound is likely a beta-2 agonist

    ANS Effects in the Bladder (Summary/Review)

    • SNS:
      • β-2 receptors (bladder wall): Relaxation
      • a-1 receptors (sphincter): Contraction
      • Result: Do not pee
    • PSNS:
      • M3 in bladder wall: Contraction
      • M3 in sphincter: Relaxation
      • Result: Pee

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    Autonomic Pharmacology Lecture Notes PDF

    Description

    Test your knowledge on the anatomy and functions of the Autonomic Nervous System, including the Parasympathetic and Sympathetic Nervous Systems. This quiz covers nomenclature, neurotransmitter synthesis, and the roles of various receptors and ganglia. Challenge yourself to see how well you understand these complex systems.

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