Chapter 3: The Neuronal Membrane at Rest Flashcards
the difference in electrical charge across the membrane in the resting neuron
resting membrane potential
a brief reversal of the resting membrane potential
action potential
3 main players in making membrane potential
- cytosol and extracellular fluid
- membrane
- transmembrane proteins
key ingredient in ICF and ECF
water
key feature of water
polar solvent
cytosol and ECF are composed of water and ()
ions
the interaction between charged ions and the polar water molecules results in () around the ions
spheres of hydration
hydrophobic compounds don’t dissolve in water due to ()
even electrical charge
proteins that help control resting and action potentials
transmembrane proteins
bond between amino acid monomers in proteins
peptide bonds
transmembrane proteins that have polar and nonpolar R groups; involved in ion selectivity and gating
channel proteins
transmembrane proteins that use ATP to transport certain ions across the membrane; also involved in neuronal signalling by pumping out Na+ and Ca2+ ions
ion pumps
a functioning nervous system required movement of (1) across (2)
- ions
- membrane
occurs when dissolved ions passively distribute evenly
diffusion
ions flow down concentration gradient when: (2)
- channels are permeable to ions
- concentration gradient exists across the membrane
the force exerted on a charged particle; reflects the difference in charge between an anode and a cathode
electrical potential
relative ability of an electrical change to migrate from one point to another
electrical conductance
in order to drive ions across the membrane electrically: (2)
- conductance - channels are permeable to ions
- voltage - electrical potential difference across the membrane
voltage across the neuronal membrane at any moment
membrane potential (Vm)
resting membrane potential value is around ()
-65 mV (inside is more negative compared to outside)
at this potential, there is no net movement of ions when separated by a phospholipid membrane
equilibrium potential
when the diffusional and electrical forces are equal and opposite, K+ stops moving
K+ ionic equilibrium potential
how much charge can be stored within the vicinity of the membrane
capacitance
ionic driving force
Vm - Eion; Vm = membrane potential; Eion = ionic equilibrium potential
due to both electric potential and concentration gradient, Na+ will want to go inside the cell; thus it is crucial to ()
keep pushing Na+ out of the cell to maintain the electrochemical gradient
an ATPase that degrades ATP when Na+ is present; ensures large [K+] inside cell and large [Na+] outside cell
Na+ - K+ pump
how easy it is fro an ion to pass through the membrane
membrane permeability of the ion
selectivity of K+ channels comes from the (1) in the (2) of the channels
- amino acid arrangement
- pore regiond
K+ channels have () subunits
4
the () allows the K+ channels to be selectively permeable to K+ ions only
pore loop-selectivity filter
explain how K+ channels prevent smaller Na+ ions to pass through
- carbonyl oxygen atoms lining the channel pore displace water molecule bound to K+, allowing K+ to pass through
- the water molecules bound to smaller Na+ ions cannot interact with the oxygens and thus are not diplaced
the resting membrane potential is close to Ek (ionic equilibrium potential of K+) because ()
the membrane is mostly permeable to K+
increased extracellular K+ (polarizes/depolarizes) membrane
depolarizes
