Autonomic Nervous System Overview
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Autonomic Nervous System Overview

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Questions and Answers

Which cranial nerve is responsible for the constriction of pupils?

  • Oculomotor nerve (III) (correct)
  • Glossopharyngeal nerve (IX)
  • Vagus nerve (X)
  • Facial nerve (VII)

    • What function is associated with the Vagus nerve (X)?

  • Constricts pupils
  • Innervates the parotid salivary gland
  • Produces tears
  • Stimulates digestive glands (correct)

    • Where is the Myenteric plexus located?

  • Between longitudinal and circular muscle (correct)
  • In the walls of the heart
  • Outside the CNS
  • Between circular muscle and luminal mucosa

    • Which of the following statements about postganglionic neurons is true?

    <p>They originate outside the CNS.</p> Signup and view all the answers

    Which plexus is the largest among the autonomic plexuses?

    <p>Celiac plexus</p> Signup and view all the answers

    What is the primary role of acetylcholinesterase (AChE)?

    <p>To hydrolyze acetylcholine in synapses</p> Signup and view all the answers

    Which type of anticholinesterase produces effects of long duration?

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

    Which of the following agents is categorized as a reversible acetylcholinesterase inhibitor?

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

    What is one of the first principles of management for organophosphate poisoning?

    <p>Gastric lavage if ingested orally</p> Signup and view all the answers

    Butyrylcholinesterase (BChE) is primarily produced in which organ?

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

    What is the primary function of the autonomic nervous system?

    <p>Control involuntary structures such as smooth and cardiac muscles</p> Signup and view all the answers

    Which effect is associated with Propranolol?

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

    Which part of the autonomic nervous system is responsible for the 'fight or flight' response?

    <p>Sympathetic nervous system</p> Signup and view all the answers

    What is the primary effect of Labetalol and carvedilol?

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

    What neurotransmitter is primarily used by the parasympathetic nervous system?

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

    Which statement about sympathetic and parasympathetic divisions is correct?

    <p>The sympathetic division inhibits digestive organs.</p> Signup and view all the answers

    Which situation would Acebutolol or Pindolol be least effective in treating?

    <p>Severe hypertension</p> Signup and view all the answers

    Bradycardia typically causes which of the following effects?

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

    Which of the following neurons would be classified as afferent neurons?

    <p>Neurons that bring sensory information into the CNS</p> Signup and view all the answers

    Which of the following is true about bronchoconstriction?

    <p>It is caused by Propranolol</p> Signup and view all the answers

    What does the term 'thoracolumbar' refer to in the context of the autonomic nervous system?

    <p>The location of the originating spinal nerves for the sympathetic division</p> Signup and view all the answers

    Which division of the autonomic nervous system is primarily involved in the 'rest and digest' response?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    What type of muscle contraction is stimulated by the sympathetic division's alpha receptors?

    <p>Contraction of smooth muscles</p> Signup and view all the answers

    What is the primary clinical use of atropine?

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

    Which of the following is a reversible cholinergic agonist?

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

    Which agent is used to treat glaucoma by decreasing eye pressure?

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

    What is the action of succinylcholine during surgery?

    <p>Muscle relaxation</p> Signup and view all the answers

    What is the main effect of anticholinergic agents like scopolamine?

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

    What condition would necessitate the use of pralidoxime?

    <p>Organophosphate poisoning</p> Signup and view all the answers

    Which adrenergic agonist is primarily used to treat hypotension?

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

    What is the primary purpose of nicotine in out-of-hospital settings?

    <p>To help quit smoking</p> Signup and view all the answers

    Which of the following is classified as an irreversible cholinergic agent?

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

    What is the effect of ibuprofen on gastrointestinal motility?

    <p>Decreases motility</p> Signup and view all the answers

    Which agent is known to induce mydriasis?

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

    In what scenario is methacholine clinically used?

    <p>To induce bronchoconstriction for asthma testing</p> Signup and view all the answers

    What class of drugs does Ipratropium belong to?

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

    Which drug primarily causes skeletal muscle contraction and is used in general anesthesia?

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

    Study Notes

    Autonomic Nervous System

    • Controls involuntary structures: smooth and cardiac muscles, glands
    • Controlled by: brain stem, limbic system, and frontal lobes (by the hypothalamus)
    • Function: maintain homeostasis of the internal environment along with the Endocrine system
    • Has 2 neuron chain

    Sympathetic (Fight or Flight)

    • Also called thoracolumbar (T1-L2)
    • Activates adrenal medulla to release norepinephrine and epinephrine
    • Stimulate activities of the effector organs (except digestive organs)
    • Functions for intense skeletal muscle activity
    • Activated in stressful situations
    • Axon: highly branched and affect many organs
    • Divided into:
      • Alpha  contraction of smooth muscle
      • Beta 1  metabolic functions
      • Beta 2  relaxation of smooth muscle

    Parasympathetic (Rest and Digest)

    • Also called Craniosacral (S2-S4)
    • Functions for maintenance
    • Activated in calm and rest situations
    • Inhibit activities of the effector organs (except digestive organs)
    • Axon: few branches and has localized effect
    • Uses neurotransmitter acetylcholine
    • Divided into:
      • Nicotinic  uses an ion channel
      • Muscarinic  uses G-protein receptor
    • Cranial outflow:
      • III 3 {Oculomotor} - pupils constrict
      • VII 7 {Facial} - tears, nasal mucus, saliva
      • IX 9 {Glossopharyngeal} – parotid salivary gland
      • X 10 (Vagus) – visceral organs of thorax & abdomen: (stimulates digestive glands, increases motility of smooth muscle of digestive tract, decreases heart rate, bronchial constriction)
    • Sacral outflow (S2-4):
      • Form pelvic splanchnic nerves
      • Supply 2nd half of the large intestine
      • Supply all the pelvic (genitourinary) organs

    Enteric Nervous System {ENS}

    • Located within the wall of the digestive tract, from the Oesophagus to anus
    • Divided into:
      • Myenteric plexus {of Auerbach}  located between longitudinal and circular muscle
      • Submucosal plexus {of Meissner}  located between circular muscle and luminal mucosa

    Preganglionic Neurons

    • Originate in the brain or spinal cord
    • Short sympathetic and long parasympathetic

    Postganglionic Neurons

    • Originate in the ganglion located outside the CNS
    • Long sympathetic and short parasympathetic

    Sympathetic System: Postganglionic Cell Bodies

    • Paravertebral ganglia  located at the sides of vertebrae and united by preganglionic into the sympathetic system (preganglionic are thoracolumbar) (postganglionic are cervical to coccyx)
    • Prevertebral (preaortic) ganglia  located at the anterior to abdominal aorta, in plexuses surrounding its major branches (preganglionic nerves reach preventable ganglia via abdominopelvic splanchnic nerves)

    Autonomic Plexuses

    • Cardiac plexus  heart
    • Pulmonary plexus  bronchial tree
    • Celiac plexus  largest.

    Cholinesterase

    • Acetylcholinesterase (AChE) (choline esterase I, erythrocyte cholinesterase, RBC cholinesterase, acetylcholine acetylhydrolase)  neural synapses, neuromuscular junctions and RBC membranes
    • Butyrylcholinesterase (BChE) (choline esterase II, pseudocholinesterase, plasma cholinesterase)  produced in the liver and found in the blood plasma

    Anticholinesterases (Cholinesterase Inhibitors)

    • Block hydrolysis of acetylcholine  (Parathion inhibits the action of the enzyme acetylcholinesterase leading to accumulation of Ach)
    • Used as smart drugs (paralysis during anesthesia, myasthenia gravis, glaucoma, Alzheimer’s disease)
    • 2 types of acetylcholinesterase inhibitors:
      • Reversible  do not covalently modify acetylcholinesterase (combine with a residue of serine in the active site). Produce effects of moderate duration : E.g., carbamates, acridine
      • Irreversible  organophosphates (phosphorylates the serine residue in the active site); produce effects of long duration (pesticide, nerve gas Sarin)

    Organophosphate Compounds

    • Drug: Ecothiophate
    • Pesticides: Parathion, Malathion
    • Nerve gases: Sarin, Soman, Tabun

    Clinical Features of An Organophosphate Poisoning

    • Includes: nausea, vomiting, diarrhea, blurred vision, bronchospasm (wheezing), bradycardia, muscle weakness, fasciculations, paralysis, seizures, coma

    Principles of Management of Organophosphate Poisoning (ABC Drugs)

    • Measures to prevent/reduce absorption (Transdermal/Oral ingestion):
      • Wash with soap and water and remove clothes
      • Gastric lavage
      • Nicotine

    Cholinergic Agonist

    • Examples: Bethanechol, Pilocarpine, Neostigmine, Physostigmine, Ecothiophate, Isophlurophate

    Organophosphate Antidotes

    • Atropine, Pralidoxime

    Cholinergic Parasympathetic Antagonist (Symp Like Effect)

    • Examples: Atropine, Ipratropium, Scopolamine

    Ganglion Blocker (Nn)

    • Example: Nicotine

    Anti-Nicotinic (Nm)

    • Examples: Succinylcholine, Tubocurarine, Mivacurium

    Adrenergic Sympathetic Agonist (Symp Like Effect)

    • Direct-acting: Examples: Epinephrine (adrenaline), Dopamine, Dobutamine, Albuterol, Phenylephrine
    • Non-selective: Examples: Propranolol
    • Non-selective, A1 blocker: Examples: Labetalol, Carvedilol
    • Partial agonist: Examples: Acebutalol, Pindolol
    • Drugs used to treat: Bradycardia, Hypertension, Asthma, Miosis

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    Description

    Explore the intricacies of the Autonomic Nervous System, including the roles of the sympathetic and parasympathetic divisions. Understand how these systems work to maintain homeostasis and respond to stress. Test your knowledge on their functions and anatomical features.

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