Resting Membrane Physiology Flashcards
the difference in concentration of a charged
particle between one point and another.
electrical potential (EP)
charged particles flow from
one place to another through ion channels or membranes.
Current flow
In other cells like
glands, macrophages and ciliated cells local changes in membrane
potential (MP) to
activate many of the cell functions.
In nerve and
muscle cells rapidly changing electrochemical impulses which are used to
transmit signals
Production of graded potential and action potential depends on :
- Presence of specific ion channels
- Resting membrane potential
Selectivity is based on
- The charge lining the channel
- Size of the channel
Channels that are always open :
Leaky channels
Gates controlled by changes in membrane potential
.Voltage-gated:
Acetylcholine binds to nicotinic receptor is an example of which type of gated channel ?
Ligand gated
What are the two types of ligand channels ?
Sensors located extracellularly
Sensors located intracellularly
Pacinian corpuscle in skin is an example of which channel ?
Mechanical
T/F: A diffusion potential is the potential
difference generated across a membrane
when a charged ion diffuses against its
concentration gradient.
False down
Which of the following would INHIBIT diffusion potential from being generated ?
A)large conc. gradient
B) low conc. gradient
C)permeable membrane
D)impermeable membrane
D
The magnitude (amount) of a diffusion
potential is measured in
millivolts (mV)
The magnitude (amount) of a diffusion
potential depends on
size of concentration gradient
The sign of diffusion potential depends on
the charge of diffusing ion
when diffusion slows and then
stops; and there is no net movement of that ion; a stage called
Equilibrium
potential
is the Diffusion potential that exactly balances
or opposes the tendency for diffusion down the concentration difference.
Equilibrium potential
Current flow depends
Net force ( conc. and electrical)
Membrane permeability
What ion has opposing forces and what are its opposing forces ?
Potassium
Electrical gradient attracts it inside
Conc. gradient attracts it outside
What is the equilibrium potential of potassium ?
-94 millivolts with negativity inside and positivity outside.
What ion has 2 forces working together to move it ? What are they
Sodium
Electrical and conc. gradients both move sodium into the cell
What is the equilibrium potential of sodium ?
Equilibrium potential for Na+ is +61 mv with
positivity inside and negativity outside
Equilibrium potential for cl-
-65 (-63)
to calculate the equilibrium potential for an ion at a given
concentration difference across a membrane, assuming that membrane is permeable to that ion.
The equilibrium potential is calculated for one ion at a time.
The Nernst equation
————————the convert of concentration difference of an ion into a voltage at a given
temperature, gas and faraday constant
Nernst potential for that ion.
Nernst potential magnitude depends on
Proportionally with the ratio of concentrations of that specific ion on two sides of
the membrane
Formula of nernst
E (millivolts) = ± 61x log concentration inside/ concentration outside
equation is used to determine the resting membrane potential
(RMP) in the cell with involvement of Na, K and Cl ions; the 3 most
important ions responsible for developing membrane potential
Goldman-Hodgkin-Katz equation
When a membrane is permeable to several different ions, then resulting
diffusion potential depends on 3 factors:
1.Electrical charge of each ion
2. Permeability of membrane to that specific ion
3. Concentration of ions inside and outside the membrane
resting membrane potential
(RMP) in the cell with involvement of Na, K and Cl ions equals to
-86 mV
when membrane is not responding to any stimulus is called
resting membrane potential [RMP].
What type of potential establishes RMP
Diffusion potential
What is the RMP in a large nerve ?
-90mV
The EP of highly permeable ions is closer to the value of the RMP due to their high permeability ?
Yes ie potassium
What channels are important for resting membrane potential ?
K leaky channels and Na K pump
T/F: Having a membrane potential does not make membrane excitable
True
Excitability depends upon
the possibility of depolarization or reversal
of polarised potential
——————- open in response to a stimulus and allow particular
ions to pass through and to change the polarized state to depolarized
state.
A) leaky channels
B)gated channels
C) EP
D) current flow
B
GP channels :
ligand gated or mechanically gated
ion channel
GP are produced at
dendrites and
soma of neuron
Hyper polarisation signals cause what kind of graded potential?
IPSP
Depolarisation graded potential causes what kind if signal
EPSP
the part of neuron from
where axon arises
Axon hillock
is the part of axon hillock
where action potential is produced.
Initial segment
chemical and electrical forces acting on
that ion are equal and no further net diffusion of that ion occurs
electrochemical equilibrium,
RMP in a large nerve with the na pump contribution =
-90
Area in nerve rich in voltage gated Na+ channels
Trigger zone in initial segment
