PNS

• Peripheral Nervous System


  • Organization of PNS
  • Functional Classification of Neurons
  • Efferent, afferent, and interneurons
  • Efferent Nervous System
  • Autonomic
  • Somatic
  • Enteric
  • Afferent Nervous System
  • Afferent and Efferent Association

  
• Components of the Peripheral Nervous System

  • Nerves
  • Ganglia

  
• Organization of Nerves


  Shown in diagrams

  
• Ganglia


  Clusters of neuron cell bodies outside the central nervous system

  
• Functional Classes of Neurons

  • Efferent
  • Afferent
  • Interneurons

  
• Functional Organization of the Peripheral Nervous System

  1. Efferent Division

  2. Autonomic Nervous System

  3. Somatic Nervous System

  
• Autonomic Nervous System


  • Exceptions to the general rule of dual reciprocal innervation by the two branches (arterioles, veins, sweat glands, salivary glands)

  
• Structures innervated by the Autonomic and Sympathetic Nervous Systems


  • Eye
  • Nasal mucosa
  • Liver
  • Gall bladder
  • Pancreas
  • Adrenal gland
  • Kidney
  • Small intestine
  • Colon
  • Rectum
  • Urinary bladder
  • Genitalia
  • Lung
  • Heart
  • Salivary glands
  • Trachea
  • Lacrimal gland
  • Stomach
  • Spleen
• Sympathetic Nervous System


  • Fibers originate in thoracic and lumbar regions of spinal cord
  • Most preganglionic fibers are short
  • Long postganglionic fibers
  • Preganglionic fibers release acetylcholine (Ach)
  • Most postganglionic fibers release noradrenaline (norepinephrine)

  
• Parasympathetic Nervous System


  • Fibers originate from cranial and sacral areas of CNS
  • Preganglionic fibers are longer
  • Very short postganglionic fibers
  • Preganglionic fibers release acetylcholine (Ach)
  • Postganglionic fibers release acetylcholine

  
• Adrenal Medulla


  Part of the sympathetic nervous system that releases epinephrine and norepinephrine into the bloodstream
• Autonomic Neurotransmitter Receptors


  • Cholinergic Receptors (Nicotinic, Muscarinic)
  • Adrenergic Receptors (Alpha, Beta)
• Cholinergic Receptors


  Nicotinic receptors found on postganglionic cell bodies of all autonomic ganglia, Muscarinic receptors found on effector cell membranes
• Adrenergic Receptors


  G protein coupled mechanism, Alpha (α) and Beta (β) receptors
• Autonomic Agonists and Antagonists

  • Atropine (binds to muscarinic receptors only)
  • Salbutamol (activates β2-adrenergic receptors)
  • Metoprolol (blocks β1-adrenergic receptors)
• Neuromuscular Junctions


  Where motor neurons connect to muscle fibers
• Poliovirus and Amyotrophic Lateral Sclerosis (ALS) are clinical conditions related to the neuromuscular junction
• Divisions of the Afferent Nervous System


  • Visceral Afferent
  • Sensory Afferent

  
• Cranial Nerves


  • Olfactory nerve
  • Optic nerve
  • Oculomotor nerve
  • Trochlear nerve
  • Trigeminal nerve
  • Abducens nerve
  • Facial nerve
  • Vestibulocochelar nerve
  • Glossopharyngeal nerve
  • Vagus nerve
  • Accessory nerve
  • Hypoglossal nerve