Nervous Tissues 116

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Nervous Tissues 11/6

• How do the peripheral and central nervous systems
  differ?
• What is the difference between afferent and
  efferent neurons?
• What are the anatomical structures of a neuron?
• What are the functions and classes of neuron?
• How do myelinated and unmyelinated neurons
  differ?
• What is the difference and significance of slow
  and fast axonal transport?
• What are neurotransmitter subclasses?
• How is target cell activity modified?
• What are direct messengers and 2nd messengers?
• How do we end a signal?
• Why are post-synaptic effects seldom all-or-none?

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Nov 11 Lab Make-up

• We do not have lab on Wed Nov 11th
• You will need to make this up on Mon, Tue, or
  Thursday. Please go to a lab and ask if they can
  let you in.

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Finish notes on smooth muscle from monday
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Our nervous system can be broken down into
central and peripheral systems based on
anatomical location.
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Structures associated with Neurons

• Soma (perikaryon)-
• Nucleus/Nucleolus
• Endoplasmic reticulum/Golgi apparatus
• Cytoskeleton
• Microtubules and Actin/Neurofibrils
• Alzheimer Disease and neural tangles
• Plasma Membrane composition-
• Polyunsaturated FA, FA length and cholesterol
• Membrane width and separation of charge
• Baby formula FA vs. Breast Milk FA?
• Dendrite-
• Axon-
• Synaptic Knob/Terminal Button/Synaptic Node
• Terminal Arborization
• Axon Collateral
• Neurons rarely (if ever) undergo mitosis (good
  and bad)
• Lipofuscin indicator of aging, wear and tear
  (lysosomes)

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What are the universal properties of neurons?
What are the functional classes of neurons?

• Universal Properties of neurons
• Excitability/Irritability-
• AP Conduction-
• Neurotransmitter secretion-
• Functional Classes of neurons
• Sensory (Afferent)-
• Interneurons (Association)-
• Motor (Efferent)-
• Glial cells are not excitable (not neurons)

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What are the three primary types of neuron and
what are their common characteristics?

• 1) Multipolar Neurons most common in body
• Contain many dendrites!
• 2) Bipolar Neurons associated with smell
• One main dendrite and one axon
• 3) Unipolar neurons Dendrite Axon!
• Soma is placed off to the side!
• Common Characteristics
• Established Membrane Potential
• More Na outside/K inside
• Hyperpolarized (normal is about -90mVolts)
• Excitability Ability to create/send a wave of
  depolarization across the lipid bilayer of these
  cells (action potential)!
• This wave of self-promoting depolarization is
  called an Action Potential

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Neuroglial cells far outnumber neurons (501) and
are critical for the support of neuron function.

• CNS
• Astrocytes 90 of brain tissue
• Support/Protect neurons
• Blood Brain Barrier
• Ependymal cells produce cerebral spinal fluid
• Microglial cells macrophages of CNS
• Oligodendrites wrap around neurons in CNS
• PNS
• Satellite cells near soma in a ganglion
• Schwann Cells wrap around neurons in PNS

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Neuoglial cells far outnumber neurons (501) and
are critical for the support of neuron function.

• What are the types of supportive cell for
  improved AP conduction?
• Oligodendrites form myelin sheath around axons in
  the brain/CNS Multiple sclerosis-
• Schwann cells form form myelin sheath around
  axons in the PNS Nerve regeneration pathways-
• Myelin sheath is very rich in polyunsaturated
  fats! Sensitive to toxic lipids
• Myelin Sheath does not permit electrical
  conduction!
• Ions cannot pass though!
• The gaps of exposed axolemma are called Nodes of
  Ranvier!
• Unmyelinated neurons also exist but have limits
  to their function!
• Especially neuronal regeneration they have no
  pathway to retrace!

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Myelin sheaths help protect neurons and helps to
conduct Action Potentials at a high rate of
speed! Neurons can be unmyelinated (slow action
potential velocity)!
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A myelin sheath creates a pathway for damaged
axons to follow/grow into/regenerate into
following injury!Unmyelinated neurons are poor
at regeneration!