Neuron Communication Quiz

Neuron Communication

• Neuron Anatomy:

  • Dendrites: Receive incoming signals.
  • Cell Body: Processes and integrates information.
  • Axon: Carries information over long distances.
  • Axon Terminal: Transmits information to the next cell.

• Action Potential:

  • A neuron transmits a signal along the axon if incoming stimulation is strong enough.
  • The neuron "fires."
  • Electrical signals are fast for immediate reactions.
  • Inside of a neuron is more negative than outside.
  • Information in the brain is coded through action potentials (electrical impulses).
  • Action potentials are all the same size and shape.
  • Differences are in the firing frequency (higher or lower).
  • Action potentials regenerate at each node.

• Synaptic Communication:

  • Synapses are chemical, not electrical.
  • Communication occurs between two neurons.
  • Threshold of activation is -55mV for an action potential.
  • Action potentials carry information through impulses.
  • Outside the neuron has no electricity. No AP outside.

• Electrical Signals & Ions:

  • Electrical signals inside neurons are called action potentials.
  • Start in dendrites, end at terminals.
  • Signals are from ion flow (atoms with charges).
  • Ions are atoms or groups carrying a charge (positive or negative) from gaining/losing electrons.
  • Inside of neuron is more positively charged than outside.

Membrane Potential

• Membrane Potential: Difference in charge between inside and outside the cell.
• Resting Potential: Approximately -70 mV (neuron is "at rest").
• Electrochemical Gradient: A combination of chemical (concentration) and electrical (charge) gradients.

Electrical Excitability

• Resting Membrane Potential: The neuron's potential when not transmitting information (maintains a state for rapid response to stimuli).
• Action potential depends on resting membrane potential - maintains -70 mV for quick actions potentials.
• Electrical excitability is due to the neuron's ability to maintain a potential that facilitates fast action potentials. The brain uses 20% of body energy.
• Resting membrane potential is -70 mV.

Maintaining Resting Potential

• 3 Mechanisms (continuous ion movement):
  • Diffusion: Natural movement from high to low concentration. Sodium and Potassium move oppositely, based on concentration differences. Chloride moves towards negative charges if possible. Requires no energy (passive).
  • Electrostatic Pressure: Positive charges are pushed away from positive charges; negative charges attract negative charges. Attracts/repel charges based on the relative polarity. Requires no energy (passive).
  • Transporters: Active transport that uses ATP (energy) to move substances AGAINST their concentration gradient. This ensures the neuron remains at its negative resting potential. Specifically, the sodium-potassium pump maintains the gradient by moving sodium out and potassium into the cell.

Ion Concentrations

• Sodium (Na+):

  • More sodium outside of the neuron than inside
  • Positive charge

• Potassium (K+):

  • More potassium inside of the neuron than outside
  • Positive charge

• Chloride (Cl-):

  • More chloride outside of the neuron than inside
  • Negative charge

• Polarized State:

  • Inside of a cell is negative, outside is positive.
  • Cell membrane is permeable to positive ions more than others due to negative interior. Neuron maintains -70 mv resting potential