01 -- electrophysiology 1

01 -- electrophysiology 1 - Electrical Properties of...

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Electrical Properties of Excitable Cells
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Neural Cell Membrane Also called “plasma membrane” Is a “semipermeable” entity some molecules can easily cross, others cannot effectively separates inside of cell ( cytosol/cytoplasm ) from extracellular fluid
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Neural Cell Membrane KEY POINT: the exchange or movement exchange or movement of items (particularly small, charged particles called ions ions ) into and out of the neuron across the cell membrane is the very foundation upon which neural function is based
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Review of Physics 101 We need to revisit 2 important physical phenomena that provide the “driving forces” relevant to the movement of ions across the membrane of neural cells
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Review of Physics 101 #1 = DIFFUSION In an given medium (air, water, etc.), molecules will tend to move from an area where they are highly concentrated toward an area where they are less concentrated is the result of random (or Brownian) motion
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Review of Physics 101 #1 = DIFFUSION If there are 2 spaces, each with a different concentration of some molecule (or combination of molecules), then there exists a concentration gradient concentration gradient
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Review of Physics 101 #1 = DIFFUSION If given a chance (provided a way to move between spaces), molecules will move DOWN DOWN their concentration gradient from high to low conc. until spaces roughly equal in conc. this is diffusion!
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Review of Physics 101 #2 = Electrical Forces Opposite charges attract one another Like charges repel one another Click here for proof of concept (by Paula Abdul)
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Review of Physics 101 #2 = Electrical Forces The movement of electrical charge (or, in this case, charged particles) is called CURRENT CURRENT Measured in units called AMPERES or AMPS AMPERES or AMPS By convention, current is defined as moving or “flowing” in the direction which positive charge moves
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Review of Physics 101 #2 = Electrical Forces The magnitude magnitude of current flow is determined largely by 2 factors: A. The difference in charge difference in charge of the positive and negative “sides” of a space called the ELECTRICAL POTENTIAL ELECTRICAL POTENTIAL measurement called VOLTS
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Review of Physics 101 #2 = Electrical Forces The magnitude magnitude of current flow is determined largely by 2 factors: A. The difference in charge difference in charge of the positive and negative “sides” of a space called the ELECTRICAL POTENTIAL ELECTRICAL POTENTIAL measurement called VOLTS
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Review of Physics 101 #2 = Electrical Forces The magnitude of current flow is determined largely by 2 factors:
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This note was uploaded on 03/23/2009 for the course BIOL 450 taught by Professor Jeremyingraham during the Spring '09 term at UNC.

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01 -- electrophysiology 1 - Electrical Properties of...

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