Neuron Quiz

NeuronAnatomyNeuron Anatomy

  • classified by the number of process**==es==** off of the cell body
    • Unipolar neurons- have on the process
    • Bipolar neurons- have two processes
    • Multipolar neurons- have many processes
  • Cell body- made up of the nucleus, cytoplasm, and organelles
  • Dendrites- on the cell body, bring impulses toward the cell body, pointy looking, like branches
  • Axon- runs from the bottom of the cell body to the axon terminal, sends impulses away from the body
  • Axon terminal- at the end of axons, knobby, release neurotransmitters to pass an impulse to the next neuron
  • Synapse- the space between an axon terminal of one neuron and dendrites of another
  • Myelin sheath- made up of Schwann cells, covers the axon, insulates and protects, helps nerve impulses travel quicker
  • Nodes of Ranvier- gaps in the myelin sheath, exposed axons, impulses can only travel in these areas

%%Neuroglia%%

  • found in the CNS or PNS
  • In the central nervous system
    • Astrocytes: support and anchor neurons to surrounding capillaries
    • \

       

  • Microglia- Provide immune response to the central nervous system
    • \

       

  • Ependymal cells- secrete and circulate cerebrospinal fluid
    • \

       

  • Oligodendrocytes- provides myelin insulation to neurons in the central nervous system
    • \

       

  • In the peripheral nervous system
    • Satellite cells- support and anchor neurons in the peripheral nervous system
    • \

       

  • Schwann cells- provide myelin insulation to neurons in the peripheral nervous system
    • \

       

^^Nerve Impulses^^

  • Action Potential- voltage change across the cell wall as a nerve impulse is transmitted
  • A nerve impulse is an electrical signal that travels along the neuron
    • arises from the movement of ions causing a change in electrical charges
  • Resting potential- a neuron’s intracellular space is negatively charged and the extracellular space is positively charged
  • neurons are stimulated by the environment or other neurons
  • action potential- depolarization, sodium rushes into the neuron and quickly reverses the charge
  • impulse moves down the neuron
  • Repolarization- as an impulse passes potassium diffuses out of the neuron
  • Sodium pump- restores the ion concentration to normal and the resting potential returns

 

  1. impulse arrives and the threshold is met
  2. voltage gated sodium channels are opened
  3. Voltage-gated potassium channels are opened and the potassium leaves the cell

   

  1. sodium channels begin to rest
    1. voltage-gated potassium channels are still open

   

  1. sodium channels are still resting
    1. sodium and potassium pump restores original levels of voltage in cells

==Channel types==

  • Membrane potential- the charge of the membrane
  • Voltage-gated channels- open and close in response to changes in the membrane potential, -55 charge
  • Ligand- gated channels- only open when a specific chemical (ligand), such as a neurotransmitter, binds to the channel, -70 charge
  • Mechanically gated channels- only open if the membrane is stretched or physically deformed
  • -70 charge- sodium moves through ligand- gated channels into the cell
  • -55 charge-Voltage- gated channels open and sodium continues to move into the cell
  • +35 charge- sodium voltage gated channels close and voltage- gated potassium gates open, potassium exits the cell
  • all of nothing function, if the threshold isn’t met than the action potential doesn’t occur
  • for big reactions action potentials are met and carried out more quickly and more times
  • Na/K Pump- active transport, moves K and Na to area of high concentration, 3 sodium ions more out as 2 potassium ions move in