Lecture Exam 3 Notes

• Ectoderm


  Creates neurons + neuroglia
• Neural tube


  Basis for brain and spinal cord
• Central Nervous System


  • Grey and white matter integration, memories
  • Integrates information, complex
  • Spinal cord, simple
• Peripheral Nervous System


  • Afferent nerves (sensory)
  • Efferent division (motor)
• Afferent nerves


  Sensory nerves that add to the nervous system
• Afferent nerves


  • Somatic (skeletal muscle, skin, joints)
  • Visceral (internal organs)
• Special senses


  Smell, sight, taste, hearing, equilibrium
• Efferent division


  Motor division of the nervous system
• Efferent nerves


  • Somatic nerves (innervate skeletal muscle, excitatory, voluntary)
  • Autonomic nerves (innervate smooth muscle, cardiac muscle, glands, adipose, homeostatic, rapid, short-lived response)
• Autonomic nervous system


  • Sympathetic (increases overall metabolism, prepares for physical activity, "fight or flight")
  • Parasympathetic (slows overall metabolism, activates digestion, excretion, reproduction, "rest and digest" or "feed and breed")
• Multipolar neuron


  • Common in PNS
  • Receives signal from other neurons
  • Cell body contains most organelles
  • Axon carries action potential
  • Branches of axon travel to multiple other cells
• Action potential


  Electrochemical signal that travels along the axon in one direction, "all or nothing" event
• Myelin sheath


  • Created by Schwann cells
  • Speeds up action potential transmission
  • Gaps at Nodes of Ranvier
• Synaptic communication


  • Electrical (rapid, coordinated, poorly adaptive)
  • Chemical (slower, gives neuroplasticity)
• Chemical synapse


  1. Action potential in presynaptic neuron

  2. Ca2+ channels open

  3. Vesicle exocytosis

  4. Neurotransmitter diffuses across synaptic cleft

  5. Neurotransmitter binds to receptor on postsynaptic cell
• Spinal cord


  • Delicate neural tissue, no mitosis, slow axonal repair
  • Integrates basic information, relays information to/from brain
  • Gray matter (sensory nuclei, motor nuclei)
  • White matter (ascending and descending tracts)
• Meninges


  Layers that protect and nourish the spinal cord and brain
• Spinal nerves


  • Exit intervertebral foramen
  • Contain both sensory and motor neurons
  • Ramus communicans connects to autonomic nervous system
• Dermatomes


  Areas of the body monitored by a pair of spinal nerves
• Reflexes


  • Monosynaptic (spinal reflex, fast, not adaptable)
  • Polysynaptic (can be spinal or cranial, can adapt over time)
• Acquired vs. Innate reflexes


  • Acquired (learned through repetition, adaptable)
  • Innate (genetically determined, "hard-wired", not much neural plasticity)
• Effectors and responses


  • Somatic (contract skeletal muscle)
  • Visceral (autonomic - cardiac muscle, adipose, glands, smooth muscle)
• ANS


  Autonomic nervous system
• ANS


  • Motor only
  • Visceral motor functions
  • Involuntary reflexes
  • Innate or acquired
  • Always active
• The ANS has two divisions
• Homeostatic


  Controls a lot to keep body alive
• Excitatory or inhibitory


  One division is more active (dominates)
• Both divisions are always active, but one dominates
• Sympathetic division


  • Increases metabolism
  • Inhibits digestive, urinary, reproductive systems
  • Causes stress-related fertility issues
• Parasympathetic division


  • Slows metabolism
  • Activates digestive, urinary, reproductive systems
• Dual innervation


  Target organ/tissue gets innervation from both sympathetic and parasympathetic neurons
• Blood vessels and sweat glands are not dually innervated (only sympathetic)
• Plexus


  Concentrated region where nerves weave together
• Antagonistic effects


  The two divisions cancel each other out with opposing effects
• Sympathetic


  Says "go fast"
• Parasympathetic


  Says "go slow"
• Preganglionic neurons


  • Always start in spinal cord
  • Synapse close to spinal cord
  • Myelinated by Schwann cells
  • Release acetylcholine
• Postganglionic neurons


  • Always excited
  • Serve as the "final common pathway"
• Ganglionic neurons


  Axons are postganglionic fibers
• Sympathetic pathway


  1. Lateral gray horn-ventral root

  2. Ventral ramus

  3. Gray ramus

  4. Splanchnic nerve

  5. Paravertebral/sympathetic chain