ANS 2

• What are the two divisions of the Autonomic Nervous System?

  Parasympathetic and Sympathetic divisions
• What neurotransmitter is primarily used by post-ganglionic sympathetic neurons?

  Noradrenaline
• What is the role of acetylcholinesterase (AChE) in cholinergic transmission?

  It degrades acetylcholine
• Describe the first 5 steps of basic neurotransmission

  1. Uptake of precursors
  2. Synthesis of transmitter using precursor
  3. Vesicular storage of transmitter at high concentrations or Degradation of transmitter by enzymes
  4. Depolarization of neurone by action potential
  5. Ca2+ enters neurone and causes influx of Ca2+ (depolarization-dependent influx of Ca2+)
• What are the two types of nicotinic acetylcholine receptors?

  nAChRs at autonomic ganglia and neuromuscular junction
• What is the function of ganglion-blocking drugs like trimethaphan?

  Used in hypertensive emergencies
• How many muscarinic acetylcholine receptor subtypes are there?

  Five (M1-M5)
• What is the effect of cholinesterase inhibitors like pyridostigmine?

  Enhances actions of endogenously released ACh
• What are common side effects of non-selective muscarinic ACh receptor agonists?

  Autonomic side effects like sweating and tachycardia
• What are the clinical uses of muscarinic ACh receptor agonists and antagonists?

  • Agonists:
  • Pilocarpine: treats glaucoma
  • Bethanechol: stimulates bladder emptying
  • Antagonists:
  • Ipratropium and Tiotropium: treat asthma and COPD
  • Tolterodine and Oxybutynin: treat overactive bladder
  • Hyoscine: treats IBS and nausea
• What are the systemic symptoms of anticholinergic drugs?

  Blurred vision, dry mouth, tachycardia
• What CNS symptoms can occur due to anticholinergic drugs?

  Delirium, agitation, visual hallucinations
• What is the Anticholinergic Burden (ACB) scale used for?

  Assessing anticholinergic risk
• What is the primary neurotransmitter at the sympathetic neuroeffector junction?

  Noradrenaline
• How is noradrenaline released at the sympathetic junction?

  By Ca$^{2+}$-dependent exocytosis
• What are the steps in noradrenergic transmission?

  1. Synthesis from tyrosine
  2. Storage in vesicles
  3. Release by exocytosis
  4. Interaction with post-synaptic adrenoceptors
  5. Re-uptake by noradrenaline transporter
  6. Metabolism by MAO and COMT
• What is the clinical use of β$_{2}$-adrenoceptor-selective agonists like salbutamol?


  To reverse bronchoconstriction in asthma
• What is the effect of α$_{1}$-adrenoceptor-selective antagonists like doxazosin?


  Treats hypertension
• What is the effect of β$_{1}$-adrenoceptor-selective antagonists like atenolol?


  Treats cardiovascular disorders
• What will students be able to do after the lectures on the autonomic nervous system?

  • Outline anatomical and neurochemical divisions of ANS
  • Compare neurotransmitter synthesis and release at cholinergic and adrenergic synapses
  • List mechanisms by which drugs influence neurotransmission
• What does the mnemonic "SLUDGE" stand for?

  • Salivation
  • Lacrimation
  • Urination
  • Defecation
  • Gastrointestinal upset
  • Emesis
• What causes SLUDGE syndrome?

  Massive discharge of the parasympathetic nervous system
• What treatments are available for SLUDGE syndrome?

  Atropine and pralidoxime
• What is the effect of nerve agents like sarin on cholinesterase?

  They irreversibly deactivate cholinesterase
• What is the primary symptom of SLUDGE syndrome?

  Prolonged over-stimulation of muscarinic receptors
• Describe the last 6 steps of basic neurotransmission

  2.exocytotic release of transmitter

  3.diffusion to post-synaptic membrane

  4.interaction with post-synaptic receptors

  5.inactivation of transmitter by degradation via enzymes or

  6.re-uptake of transmitter (neuronal) or

  7.re-uptake of transmitter (non-neuronal)

  8.interaction with pre-synaptic receptors
• What enzyme catalyses acetylcholine synthesis?

  Choline acetyltransferase (CAT)
• What enzyme catalyses acetylcholine degredation?


  (Acetyl)cholinesterase (AChE)
• Give the word equation for acetylcholine synthesis

  acetyl CoA      +           choline  -->      acetylcholine    +    coenzyme A
• Give the word equation for acetylcholine degradation

  acetylcholine    --->             acetate    +    choline