Module 1: Membrane Electrophysiology, Nerve and Synaptic Physiology Flashcards
Interaction between the chemical gradient and electrostatic force
Resting membrane potential
T or F: Proteins are intrinsically negative and cannot readily pass through cell membrane.
T
Combination if the following results in the RMP:
Potassium diffusion
Sodium diffusion
Na, K, ATPase
Major determinant of RMP
Potassium
T or F: In normal nerve fiber, the permeability of the membrane to K is about 100 times as great as to Na.
T
Diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion
Nernst Equation
Determined by the ratio of the concentrations of that specific ion on the two sides of the membrane
Nernst potential
T or F: The greater the ratio, the greater the tendency for the ion to diffuse in one direction, and therefore the greater the Nernst potential requires to prevent additional net diffusion
T
A phenomenon of solutions that contributes to the formation of an electrical potential across a cell membrane
Gibbs-Donnan equilibrium
A rapid, all-or-none change in the membrane potential followed by a return to the resting membrane potential
Action potential
_______________ in the plasma membrane are the basis for action potentials.
Voltage-dependent ion channels
T or F: action potentials have stereotypical size and shape, are propagating, and are all-or-none.
T
Requirements for an action potential
Lipid bilayer
Unequal distribution of ions
Selective permeability of membrane
Makes the membrane potential LESS negative
Depolarization
Makes the membrane potential MORE negative
Hyperpolarization
Is the membrane potential at which the action potential is inevitable
Threshold
The period during which another action potential cannot be elicited, no matter how large the stimulus
Absolute refractory period
Begins at the end of absolute refractory period and continuous until the membrane potential returns to the resting level
Relative refractory period
T or F: During relative refractory period, action potential can be elicited only if a larger than usual inward current is provided
T
Occurs when the cell membrane is held at a depolarized level such that the threshold potential is passed without firing an action potential
Accomodation
Propagation of action potential
Away from the stimulus
All or Nothing Principle
T or F: Anterograde-away from the center, Kinesin
T
T or F: Retrograde-towards the center, Dynein
T
T or F: Nerve cells are capable of division.
F, they are incapable
T or F: Nernst potential is potential OUTSIDE the membrane.
F, inside
T or F: Sign of Nernst potential is (+) if ion diffuses from inside to outside.
T
Glial cells that regulate microenvironment of the CNS
Astrocytes
Produces myelin sheath
Schwann cells
Glial cells that are capable of phagocytosis (macrophages)
Microglia
Glial cells that are responsible for CSF production
Ependymal cells
Signals are transferred form one cell to another via a synapse
Synaptic transmission
Low resistance pathway between cells that allows current to flow directly from one cell to another
Electrical synapse
Communication occur via intermediaries called neurotransmitters
Chemical synapse
Key events in the presynaptic membrane
Action potential..
Entry of calcium..
Release of NT
Key events in the postsynaptic membrane
Binding of NT..
Response
Opening of calcium channels
Depressed conduction through chloride or potassium channels
Various changes in the internal metabolism
Excitation
Opening of Cl ion channels through the postsynaptic neuronal membrane
Increase in conductance of potassium ions out of the neuron
Activation of receptor enzymes
Inhibition
Mediate chemical signaling between neurons
Neurotransmitters
Criteria to be a neurotransmitter
There should be specific receptors for it
The cell must be able to synthesize the substance
Released on depolarization of the terminal
There should be specific receptors
Acetylcholine: Origin? Function?
Origin-basal forebrain (nucleus basilis)
Function-learning, memory
Noreepinephrine: Origin? Function?
Origin-locus ceruleus
Function-arousal, wakefulness
Dopamine: Origin? Function?
Origin-substantia nigra
Function-fine tuning of movements, reward
Serotonin: Origin? Function?
Origin-median raphe
Function-mood, sleep
Inputs that depolarize the postsynaptic cell, bringing it closer to threshold and closer to firing an action potential
Excitatory Postsynaptic Potentials (EPSP)
EPSP is caused by opening of
Na and K channels
Inputs that hyperpolarize the postsynaptic cell, moving it away from threshold and farther from firing
Inhibitory Postsynaptic Potentials (IPSP)
IPSP is caused by opening of
Cl channels
Process of adding up postsynaptic potentials and responding to their net effect
Summation
Two types of summation
Temporal summation
Spatial summation
Most prevalent NT in the brain; excitatory
Glutamate
Dopamine: excitatory or inhibitory
Both
Secreted by synapses in the spinal cord; inhibitory
Glycine
GABA: excitatory or inhibitory
Inhibitory
Controls long term behavior and memory; inhibitory
Nitric oxide
T or F: Nitric oxide NEEDS receptor.
F
