ELECTROPHYSIOLOGY Flashcards
makes the membrane impermeable to ions and water soluble materials
bilayer of lipids
most abundant lipid in the plasma membrane
phospholipids
major cation inside the cell
potassium
major cation outside the cell
sodium
major anion outside the cell
chloride
major anion inside the cell
proteins
amphiphatic (contains both hydrophilic and hydrophobic regions)
phospholipids
non-polar, hydrophobic part of the phospholipid
fatty acid tails
polar, hydrophilic and exposed to aqueous environment
phosphate head groups
two types of transport processes
active and passive
always open
contribute significantly to the resting membrane potential
plasma membrane has more K ion leakage than Na ion channel
increase K ion permeability
leak (non-gated ion channel)
open and close because of some sort of stimulus
when the open they change the permeability of the cell membrane
regulated (gated) ion channel
open or close in response to small voltage changes across the cell membrane
when cell is stimulated, that relative charge changes and voltage gated ion channels either open or closed
voltage gated ion channels
regulated by ligands
example: acetylcholine attaches to a receptor
ligand gated ion channels
the ligand molecule itself can open or close the channel by binding to a portion of the channel protein as in the case of acetylcholine
direct ligand gated channel
ligand may act indirectly via a protein called G protein that activates another secondary messenger in the cytosol that in turn operates the gate
indirect ligand gated channel
regulated by mechanical stimulus such as pressure or stretch
opens and closes in response to mechanical stimulation in the form of vibration, pressure, or tissue stretching
mechanically gated ion channels
number of channels that are open in a membrane
channels open - increase
channels close - decrease
membrane conductance
potential difference generated across a membrane that is being generated as a result of the differences of the concentration of an ion
diffusion potential
diffusion potential wherein the electrical and chemical gradient for the certain ion is equal
net diffusion will be zero
equilibrium potential
measured potential difference across the cell membrane in millivolts
established by diffusion potentials
resting membrane potential
generation of resting membrane potential
selective membrane permeability
sodium potassium pump
concentration of the intracellular impermeable ions
more K leak channels in the membrane
K channels are leakier compare to Na channels
concentration of K is greater inside than outside; movement is from inside to outside
high permeability to potassium
electrogenic pump
generates and maintains the ionic concentration gradient
indirect contribution
sodium potassium pump
state in which membrane is polarized at rest, negative inside and positive outside
polarization
membrane potential becomes less negative than resting potential (close to zero)
depolarization
membrane potential is more negative than the resting membrane
hyperpolarization
restoration of normal polarization state of membrane
repolarization
will reduce efflux of K+ leads to depolarizarition
hyperkalemia
accelerate efflux of K+ leads to hyperpolarization
hypokalemia
produced by weak stimulus
small deviation from the resting membrane potential of -70 mv
travels a short distance (local spread) from point of stimulus and eventually dies out (cannot propagate)
signals are graded
can undergo summation
can be depolarizing
local potential
multiple stimulus fired simultaneously
spatial summation
1 stimulus but fired fired repeatedly the response will also increase
temporal summation
property of excitable cells
stereotypical in shape
propagating
all or none
non decremental
always excitatory
does not undergo summation
action potential
