autonomic nervous system

• Autonomic Nervous System


  Part of the Peripheral Nervous System that acts on organs, glands and smooth muscles, controlling involuntary responses

  
• Central Nervous System (CNS)


  • Brain and spinal cord

  
• Peripheral Nervous System (PNS)


  • Located outside the brain & spinal cord
  • Receives stimuli from the CNS and initiates responses to the stimuli after it's interpreted by the brain

  
• Autonomic Nervous System (ANS)


  Controls and regulates the heart, respiratory system, Gastro-intestinal tract, bladder, eyes and glands
• Somatic Nervous System


  Opposite of the Autonomic Nervous System
• Sympathetic Nervous System (SNS) and Parasympathetic Nervous System (PSNS)


  Control the same organs but have opposing effects
• Exceptions to the above


  • Vasculature exclusively controlled by SNS
  • Sweat glands are induced by both SNS and PSNS
• Receptor


  A protein which binds to a specific molecule
• Ionotropic receptor


  Ion channels
• Metabotropic receptor


  1. protein coupled receptor
• Ligand


  A molecule which binds to a receptor (inorganic molecules, proteins, hormones, neurotransmitters)
• Synthesis of adrenaline and noradrenaline


  Tyrosine - L-Dopa - Dopamine - NE - E
• Catecholamines


  Dopamine, NE and Epinephrine
• Monoamines


  Dopamine, NE, Epinephrine, serotonin and histamine
• Sympathetic Nervous System (adrenergic)


  Uses Norepinephrine as its neurotransmitter
• Adrenergic agonists


  Drugs that initiate a response
• Adrenergic blockers/Antagonists


  Drugs that prevent a response
• Sympatholytics or adrenolytics


  Mimic the effect of blockers/antagonists
• Types of adrenergic receptors


  • Alpha-1
  • Alpha-2
  • Beta-1
  • Beta-2
• Alpha-1 receptor


  Vasoconstriction of blood vessels, urinary retention, pupil dilatation
• Alpha-2 receptor


  Receptor commonly in CNS, inhibits release of norepinephrine, decreasing vasoconstriction, decreasing blood pressure
• Beta-1 receptor


  Commonly located in the heart, increase in heart rate and force on contraction
• Beta-2 receptor


  Relaxation of smooth muscle in bronchi, uterus, peripheral blood vessels
• Adrenergic agonists


  • Norepinephrine
  • Epinephrine
  • Isoproterenol
  • Phenylephrine
  • Xylometazoline
  • Dobutamine
  • Salbutamol (Albuterol)
  • Terbutaline
• Norepinephrine


  Activates all alpha receptors and Beta 1
• Epinephrine


  Activates all alpha and beta receptors
• Isoproterenol


  Activates all beta receptors
• Phenylephrine


  Activates alpha 1 receptors, reduces swelling via peripheral vasoconstriction
• Xylometazoline


  Activates alpha 1 receptors in arterioles of nasal mucosa, used as a nasal decongestant
• Dobutamine


  Activates beta 1 receptor, increases inotropic (force of contractility) and chronotropic (Heart rate) effects, used in cardiogenic shock
• Salbutamol (Albuterol) and Terbutaline


  Activate beta 2 receptor, used in asthma
• Dopamine


  Depending on the dose, has variable physiologic effects, used in septic and cardiogenic shock
• Dopamine at doses < 2 mcg/kg/min

  Stimulates dopamine receptors, resulting in vasodilatation
• Dopamine at doses between 5 and 10 mcg/kg/min


  Stimulates beta-1 adrenergic receptors, resulting in increased cardiac output
• Dopamine at doses > 10 mcg/kg/min


  Stimulates alpha receptors, leading to vasoconstriction
• Adrenergic antagonists


  • Prazosin
  • Tamsulosin
  • Chlorpromazine
  • Phentolamine
  • Phenoxybenzamine
• Prazosin and Tamsulosin


  Block alpha 1 receptor, commonly used for benign prostatic hyperplasia (BPH)
• Chlorpromazine


  Blocks alpha 1 and D2 receptor, commonly used as an antipsychotic
• Phentolamine and Phenoxybenzamine


  Block all alpha receptors, used in Pheochromocytoma
• Sympathomimetics


  Don't actually bind to either alpha or beta but they mimic the effect of a sympathetic agonist