Flashcards in Electrical Signaling Deck (45):
Cells specialized to receive, process and transmit information with high fidelity over long distances
Cells specialized to detect specific environmental cues
Cells that monitor, support and maintain Nervous system function
Cells specialized to receive Neuronal signals and create responses (Generally Non-Neuronal)
Two components of a neuron.
Somatodendritic and axonal
Specialized sites of excitatory synaptic contact for reception of chemical signals at the synapse
Dendritic spines -
Contain high levels of receptors that convert chemical signals to electrical signals
Sites of inhibitory synaptic contact and transmit all synaptic signals to soma
Integrates synaptic signals, generates complex firing rhythms and links neuronal activity to gene expression
initiates signaling down the Axon
transmits signals in an all-or-none fashion to post-synaptic follower cells
Axonal Terminations - Specialized site for conversion of Electrical Signals into chemical signals that are released onto follower cells
Synaptic bouton -
Contain highly concentrated packets of neurotransmitters in vesicles that are released when Bouton depolarizes.
The property of matter that describes how the matter interacts with the Electromagnetic Force is called the...
The Potential Energy a charge feels due to its location in an Electric Field is called the
The standard reference Electrical Potential from which other potentials are measured is the
Earth's electrical potential (aka ground)
A _____ _____ is generated when + and - charges are separated
across a lipid bilayer
Membrane potential (volts)
_____ _____are seen when positive and negative charges are imbalanced, producing a Net Separation of Charges
Only if charges are kept from ____ ____ can an electrical potential difference be maintained.
Neuronal Membrane potentials are normally measured to be between ___mV and ____ mV.
-100 mV and +100 mV
Standard convention for membrane potential is
(inside potential - outside potential)
What are the two membrane potential determinants?
Charge displacement and membrane thickness
Thicker membranes show _____(larger or smaller) potential change for the same amount of displaced charge.
When stimulated, Neurons, and other excitable cells, can produce rapid, transient changes in membrane potential called:
Neuronal Electrical Signaling involves the regulated movement of Ions across the lipid bilayer through _____ _____
T or F. In the presence of a cation, local water orientation is random
FALSE - dipoles dissipate (+) charge over a large area to lower the energy of solvation; interacting waters are called waters of hydration
Ions cannot cross the lipid bilayer because they would have to give up their________ to do so. The energetic cost of losing them is too high.
waters of hydration
- Highly selective cation channels
- ions pass bilayer by following low energy pathways down center of complex
- short, narrow segment called selectivity filter provides replacement O2s for lost waters of hydration
- water filled central cavity rehydrates ions in middle of passage to allow for ion rehydration
- Broadly selective cation or anion channels
- large water filled pathway runs down center of complex
- Fixed rings of charge line central channel and select for charge of permeating ions
Multiple binding sites within the P(ore)-Loop channel help increase _____ and _____
permeation and selectivity - single ion bound in pore is too stable to permeate at high rate, but binding of a 2nd destabilizes both, increase rate of mvt
Name some examples of Cys-Loops receptors and the type of ion they select for (cation or anion).
- GABA-A receptors - anions
- Nicotinic ACh receptors - cations (Ca2+ to excite muscles)
- Glycine receptors - anions
- 5-HT Type 3 receptors - cations
In cys-loop receptors, negative charge rings select for ____ using ____ residues, while positive charge rings select for _____ using ____ residues.
cations, acidic residues
anions, basic residues
In cys-loops receptors, ____ channels can partially select between divalent and monovalent ions.
Aqueous pore cannot select between monovalent cations, therefore reversal potentials tend to be near ____mV
Ability of channels to pass ions across membrane - tightly regulated
Proteins in cell membrane called channels selectively let ions pass lipid bilayer
Mvt of ions across lipid bilayer produces ____ ____
In terms of current, negative currents are + ions moving ____the cell across the lipid bilayer. While positive currents are + ions moving ____ the cell.
For each cycle, how much net charge does Na/K ATPase pump out of the cell?
Membrane potential that balances an ion's concentration gradient
In Ohm's Law, what determines the current that flows for any given conductance?
Driving Force = (Vm - Ex)
What is the slope of the line that relates current flow to driving force?
What is a reciprocal of conductance and a measurement of how difficult flow is along a given pathway?
What is the system attractor and equilibrium point?
Ek (potential of potassium)
At rest, what channels have the highest conductance?
A single ion channel is SIGNIFICANTLY faster/slower than the Na/K ATPase channel?
FASTER (7,000,000 ions per second for ion channel compared to 3000+ ions/min for ATPase)