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Neuro Phys - Exam 1 - Ch. 5 - Excitable Membranes

Terms in this set (57)

Action potentials are ___ phenomena
electrical
Ion flow creates ___
electrical currents
What does neuron size affect?
Ease of action potential generation
Speed of action potential propagation
Electronic vs. Saltatory Conduction
Speed of action potential propagation
What is Ohm's Law? What are the other 2 variations of the law?
I = gV
I = V/R
V= IR
What does each variable stand for in Ohm's Law?
Current (I) = conductance (g) x potential difference (V)
What is R in Ohm's Law?
Resistance (R) = 1/g
What are the variables in I = V/R
Current = voltage / resistance
What is electrical potential measured in?
Volts
What is resistance measured in?
OHMs
What are currents measured in?
Amps
What are the 4 electrical concepts? What are their variables?
Potential Difference (Voltage, V)
Current (I)
Conductance (g; inverse of R)
Capacitance (c)
What is potential difference?
a measure of the potential energy that must be used to move a positive charge from one location to another
What is potential difference measure in?
Volts (V)
What is a word that helps to remember potential difference?
Electromotive force
What are the ionic gradients modeled as in excitable membranes?
Batteries
What keeps the ionic 'batteries' charged?
The Na+-K+ ATPase pumps
What does the conductor/resistor diagram represent in the electrical model of an excitable membrane?
Ion Channels
What does the capacitor diagram represent in the electrical model of an excitable membrane?
Membrane/Phospholipid bilayer
What does the current generator diagram represent in the electrical model of an excitable membrane?
Sodium-Potassium ATP pump
What is current (I) defined as?
The rate at which positive charges move between the two locations that represent a potential difference
What is the equation for current?
I= Q/t = charge/time
What are the units for current (I)?
Amps
What is current carried by in nerve/muscle cells?
Positive and negative ions in solutions
What is a conductor?
Something through which current flows
What is conductivity?
Ability to conduct electric current
What is conductance?
Capacity to conduct electric current
What is the capacitor?
The membrane
Does the capacitor have short or longer term energy storage?
Short
What is the equation for capacitance?
C=Q/V
The ___ of the membrane is positive and the ___ of the membrane is negative
inside, outside
Resting K+ Channel
Always open
Voltage-gated Channel
Opens in response to change in the membrane potential
Ligand-gated Channel
Opens in response to a specific extracellular neurotransmitter
Signal-gated Channel
Opens in response to a specific intracellular molecule
What two forces tend to move ions?
Chemical force (concentration gradient)
Electrical force (opposite charges attract, like charges repel)
Cations are ___ charged
positively
Anions are ___ charged
negatively
3 properties of the phospholipid bilayer
Allow rapid ion conduction
Specific to an ion
Open and close depending on stimuli (gating)
Vm = ___
membrane potential
Is inward current positive or negative?
negative
Is outward current positive or negative?
positive
What is not an accurate formulation of Ohm's Law?
V=Ig
Under resting conditions, the electrical force acting on K+ is attempting to ___
Keep K+ inside the cell
In an electrical model of an excitable membrane the/an ___ is modeled as a 'capacitor'
Cell Membrane
The exodus of Cl- from a nerve cell to the extracellular fluid generates an ___
inward current
An ion channel opens when a neurotransmitter binds to a receptor that is associated with the channel. This is a type of ___
Ligand gated channel
What is resting membrane potential
potential difference across cell membrane
How is resting membrane potential created?
a separation of charged particles by the capacitance of the membrane
What is the concentration gradient
difference in concentration between the intra-cellular and extra-cellular spaces
What does the concentration gradient create
a voltage source
What type of ion diffusion does a chemical force undergo?
concentration gradient
What type of ion diffusion does an electrical force undergo?
potential difference across membrane
What is the equilibrium potential
when chemical and electrical forces are balanced
One does one cycle of the Na+-K+ pump use/move
one ATP and moves 3 Na+ out and 2 K+ in
The larger net driving force for ___ than for ___
Na+. K+
More resting channels for ___ than for ___, therefore greater conductance for ___ than for ___
K+, Na+
K+, Na+
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