Neuronal Membrane Potential Flashcards
The nervous system continually ___, ____ and _____ information
- Transmit
- Integrate
- Proccess
What information travels through an ascending pathway/tract?
Sensory/ Inputs/ Afferent
What information travels through a descending pathway/tract?
Motor/ outputs/ Efferent
Defined pathways are ____
Networks
The response to an input is a Neuron is a result of what?
Change in Membrane Potentional
The strength of the input is encoded by a _____________
The magnitude of change in the membrane potential
Proteins tend to have what kind of charge?
Negative (Anionic)
Membrane potential measure what?
The strength of attraction between ions along the surface of the membrane
What kind of ions are typically found on the outer surface of the membrane?
Cations (+)
What kind of ions are typically found on the inner surface of the membrane?
Anions (-)
What is the typical value of a membrane potential?
-65 mV
The sign of a membrane potential indicates what? Ex. -65mV
polarity
The number of a membrane potential indicates what? Ex. -65mV
Strength of electrical force
A change in membrane potential is caused by what?
redistribution of ions (current)
_____ is the movement of ions
Current
Channels are dependent on ____
Signals
Neurotransmitters are classified as what kind of signals?
Ligands
What kind of channel is dependent on the change in membrane potential as a signal?
Voltage-gated
_____ is defined as relaying information from location to another with in the body
Transmission
____ is defined as adding multiple inputs from multiple sources
Integration
____ is the conversions of nervous inputs into outputs
Processing
Neurons differ on histological appearance (4 categories)
Unipolar
Bipolar
Pseudo-Unipolar
multipolar
Membrane potential ___ the inputs to a neuron
encodes
The membrane potential results from a _______ between the inside and outside of the neuron.
Separation of ionic charge
______ charge accumulates along the cytoplasmic surface of the membrane due to no diffusible proteins.
Negative
_____ charged ions line up along the extracellular surface of the membrane
Positively
The membrane potential measures the ____ between ions along the inner and outer surface of the membrane
Force of attraction
The membrane potential is proportional to the number of _____ and ______ that accumulate along the two surfaces of the membrane.
- positively
- negatively charged ions
The membrane potential is expressed in both its ___ and its ___
- Magnitude
- polarity
Polarity is referenced to what side of the membrane potential
-cytosolic
The strength of the electric static attraction between ions across the membrane is what ?
Magnitude
Why are ion channels needed for a current to pass through the membrane
Because the membrane is impermeable to ions
____ channels are controlled by ligand binding to the channel protein to induce the conformational change
Ligand Gating
_____ channels require the attachment or detachment of a phosphate group to the channel protein to induce a change in conformation
Phosphorylation
_____ channels respond to changes in the electrical potential of the adjacent membrane
Voltage gating
_____ channels respond to physical distention of the membrane or change in membrane tension to cause a conformational change
Mechanical forces
How do ion specific channels filter ions (2 mechanisms)?
- pore size
- active sites
Under normal concentration gradients what ion(s) concentrations are low on the inside but high on the outside of the cell?
Na+
Ca++
CL-
Under normal concentration gradients what ion(s) concentrations are high on the inside but low on the outside of the cell?
K+
The neuronal membrane is impermeable to what ion(s)?
Na+
Ca++
CL-
The neuronal membrane is permeable to what ion(s)?
K+
A change in membrane potential is a result of _____ across the neuronal membrane
Ionic currents
What gradient is the movement of ions from a high concentration to a low concentration?
Chemical gradient
What gradient is described as, like charges repelling; opposite charges attracting
Electrical gradient
What two forces cause ions to flow through transmembrane channels
- Chemical Gradients
- Electrical Gradients
The strength of an ionic current across a membrane will vary in t direct proportion to ___ and ____
- Strength/magnitude of the gradient
- conductance of the membrane to that ion
The flow of ions (quantity per unit time) across the membrane is referred to as what?
I: Ionic “current”
What determines the chemical gradient?
(Ci – Co): Concentration difference (inside minus outside)
What reflects how readily the ion will pass through channels, relative to the strength of the gradient?
g:membrane “conductance” to a particular ion
What expresses the electrical potential that will balance the concentration gradient for an individual ionic species?
The Nernst equation
when the membrane potential (Vm) equals the Nernst potential, the system will be in _____
Steady state
The electrical potential required to counter-balance the diffusion force arising from the concentration gradient is referred to as _____
(Ei-Eo) The Nernst equilibrium potential or (E)
_________tells us that the membrane potential is due to the individual electrochemical gradients, as well as to the membrane conductance to individual ions
The Goldman equation
In the Goldman equation, Vm is dependent on what two variables
- Ex: the Nernst equilibrium potential for each ion (K+, Na+, Cl-)
- gx: the membrane conductance for each ion
