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Lecture 16
Terms, Vocabulary & Concepts
Undergraduate 3

Additional Anatomy Flashcards




A small mass of nervous tissue outside the brainand spinal cord, it is closely associated ith cranial and spinal nerves. In the PNS system.
Resting Membrane Potential

A resting neuron has potential energy (like a fully charged battery in an unused cell phone) called resting potential, when a neuron is not conducting a nerve impulse.
The energy exists b/c the cell membrane is polarized, positively charged ions are stashed outside the cell, negatively charged ions inside.
The outside of the cell is positive b/c positively charged sodium (Na+) ions gather around the outside of the cell membrane.
At rest, the neuron’s cell membrane is permeable to potassium, but not to sodium
Positively charged potassium ions contribute to the positive charge by diffusing out of the cell to join the sodium ions.
The inside of the cell is negative b/c of the prescience of large, negatively charged proteins and other molecules stuck inside the cell because of their size (selective permeability)

Resting Potential in Cells
  • Cells at rest have a charge gradient across the lipid bilayer impacted by:
    • differential permeability of the membrane to ions
    • differences in ion content on either side of the membrane
  • -70 mV is the typical cellular resting membrane potential
    • Inner membrane cytoplasm is negative relative to the iterstital space (extracellular space) which is positively charged.
  • Positively charged Na+ ions are onthe outside of the cell membrane. Positively charged K+ ions that were previously in the cell diffuse out of the cell..
  • This causes the inside of the cell to be negative while the ouside of the cell is positive.
  • The cell is polarized maintained by a sodium-potassium pump, more K+ diffuses out of the cell than Na2+ diffuses in. 
  • Neurons use changes in the membrane potential to receive, integrate, and send signals.
Graded Potentials
  • Short distance communication.
  • Vary in amplitude depending on strength of the stimulus.
      • Depends on how many ligands or mechanically-gated channel are opened or closed.
  • Can generate an actional potential
    • Typically generated in dendrites and cell bodies of neurons.
Action Potentials
  • Long distance communication.
  • All or nothing event.
K+ Leakage Channels
K+ diffuses down their steep concentration gradients and out of the cell via leakage channels. Loss of K+ results in a negative charge on the inner plasma membrane face.
Electrical Signals Produced by Neurons and Muscle Fibers Dependon 4 Types of Channels
  • Leakage Channel (K+): 
    • Does not reqire energy.
    • Moves ions down concentration/charge gradient. Alwaysopen
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