Lecture 3/4 Flashcards
Electrical impulse is initiated in the ________, travels thru cell body down the axon to presynaptic terminal
dendrite
Impulses/Action potentials are the result of coordinated opening and closing of multiple _______ that are permeable to Na, K, Cl,Ca
ion channels
Name the 3 electrical signals of nerve cells.
Receptor potential (graded) Synaptic potential (graded) Action potential (all or none)
Resting membrane potential is a ___________
intrinsic property of the cell
Define current
movement of charge in a given time period
What 2 factors determine amplitude (size) of a current?
potential difference between electrodes and electrical conductance of the medium between them.
Electrical potential is…?
amount of potential energy per unit of charge at given location
Potential difference is…?
difference in potential between 2 locations
What is the term for ease of flow between 2 points?
conductance
Resistance is…?
inverse of conductanceand measured in ohms
What is Ohm’s law
V=IR
V=voltage, I=current, R=resistance
Girls transform into drag kings? https://www.youtube.com/watch?v=uK98jrF_0Og
…
What is a capacitor?
2 conductors (solution inside and outside the cell) separated by an insulator.
A seperation of charge occurs when?
charge is introduced onto one of the conductors and it pushes similar charges away from the other conductor since they repel.
Capacitance is measures of what?
how much charge needs to be transferred from 1 conductor to another to set up a given potential difference
____________ across membranes drives ion flux.
Charge seperation.
once it occurs, potential difference drives ions from one point to another
Flow of ions creates _________
current.
no ion gradient means no voltage difference and no current flow
What are the 3 main ions involved in neuron excitability?
Na+
K+
Cl-
Membrane proteins regulate _______ into and out of cell.
ion flux
Name 2 characteristics of ion transporters
Actively move ions against concentration gradient.
Create ion concentration gradients
Name 2 characteristics of Ion channels
Allows ions to diffuse down concentration gradient
Cause selective permeability to certain ions
What are 2 factors that cause the resting membrane potential
the separation of ions across the cell membrane
the permeability of the membrane itself to those ions
What does the Nernst equation predict?
Voltage created by diffusion of a single ion type.
For a positively charged ion, if the membrane potential is more _______ than the equilibrium potential then the direction of flux is ________
positive, out of the cell
For a positively charged ion, if the membrane potential is more negative than the equilibrium potential than the direction of flux is ________.
into the cell.
The farther away from the equilibrium potential the membrane voltage is, the ________
larger the current
Resting membrane voltage depends primarily on ________.
K+ concentration gradient
What do we calculate using the Goldman equation?
Relative permeabilities of each ion in addition to voltage created by diffusion
T/F: The value of the resting membrane potential calculated by the Goldman equation cannot fall between Nernst potentials.
False
T/F: membrane voltage is determined by K+ distribution at rest.
True
For any ion, its distribution across the membrane is determined by…?
Chemical gradient
Electrical gradient
Permeability (conductance)
Maintaining the resting membrane potential is an ________ process
active
The resting membrane potential is NOT an equilibrium potential. Why?
It relies on expenditure of ATP by ion pumps for maintenence.
Membrane potential can be changed by altering ion gradients or _______.
permeability
What is the action potential a result of?
increasing permeability to Na+ and K+
