Block 2 Flashcards
Most brain function can be explained by the influence that the movement of these 3 salt atoms (ions) across the neuronal membrane have on the electrical charge of a neuron
potassium, sodium, chloride
All matter is formed of __
atoms
Atoms bond together into aggregates called __
molecules
Atoms that have either lost or gained a charge
ions
Positively charged ions
cations
Negatively charged ions
anions
A negatively charged surface attracts __ ions
positive
A positively charged surface attracts __ ions
negative
one mole of particles in one liter of solution
one molar solution
μM (micromole)
one millionth of a mole
mM (millimole)
one thousandth of a mole
nM (nanomole)
one billionth of a mole
intracellular environment is rich in what ion?
potassium
extracellular environment is rich in what ion?
sodium
adaptation occurred and first existing neurons placed leaky, porous proteins in the membrane called ___ so that ions could enter and exit
ion pores
proteins anchored in the membrane that form a channel from inside to outside
ion pores
monomer ion pore
only have one protein
polymer ion pore
many proteins linked together
each of the ion pores have ___ trans-membrane regions and __ intracellular and extracelular regions
hydrophobic ; hydrophilic
What happens when potassium channels are open? Why does this happen?
potassium will move across the membrane and down its electro-chemical gradient following the Laws of Thermodynamics
Describes the process of disorder in a system; evens out highly organized concentration gradients; ex diffusion: movement of ions from areas of high concentration (organized) to areas of low concentration (disorganized)
entropy
Pushes K+ out of the cell and down the concentration gradient; depends on the difference between extracellular and intracellular concentrations (greater the difference = greater the push)
entropy
principles of opposites attracting; electrostatic force: developing negative charge in a cell will stop the flow of positively charged potassium from leaving the cell
enthalpy
the point where enthalpy (electrostatic force) balances out entropy (diffusion force) for any charged ion
equilibrium
the difference in ___ across the cell membrane gives the cell its charge (an electrical value)
ion concentration
the electrical charge necessary to balance out the process of diffusion; can be calculated by the nernst equation
equilibrium potential
equilibrium potential for potassium; K+ will always try to make the cell this value
-93MV
actual charge inside the cell
membrane potential
resting potential of cell
-70mV
upward deflection; gaining of positive charge in the neuron; charge goes towards 0
depolarization
downward deflection; gaining of negative charge in the neuron; charge goes away from 0
hyperpolarization
Which ions influence the vM of a neuron?
sodium, chloride, potassium
equilibrium potential for sodium
+56 mV
equilibrium potential for chloride
-66mV
The equilibrium potentials for chloride and sodium have a __ influence on the vM
depolarizing
__ of each ion plays a role in the vM
permeability (leakiness)
Relative Permeabilities (most permeable to least permeable)
K : Cl : Na
Resting Potential of the cell should be closer to __ and __ than __
Potassium, Chloride, Sodium
determines the vM by considering the concentration of ions and permeability of ions across the membrane
Goldman equation
Makes up for the 3mV unaccounted for by the Goldman equation
sodium/potassium pump
Maintains the ion gradient, prevents continuous leaking
sodium/potassium pump
Sodium/potassium pump moves __ sodium ions __ and __ potassium ions __
3 sodium ions out; 2 potassium ions in
