Neurons (5/11) Flashcards
(26 cards)
Negative membrane potential
more positive charge on the outside and less positive charge on the inside
Potassium concentration
higher inside than out
Sodium concentration
lower inside than out
Chloride concentration
lower inside than out
Na+K+ATPase
3 sodium out and bring 2 potassium in by hydrolyzing ATP
Resting membrane potential
-70 mV
Depolarization
the membrane potential becomes less negative and approaches 0
OVershoot
the membrane potential becomes positive
Repolarization
Returning to the resting membrane potential after the neuron has depolarized
Hyperpolarization
The membrane potential becomes more negative than the resting membrane potential
Signal transmission
neurotransmitters released in synaptic clef and binds to receptors to affect graded potential (most are excitatory-EPSP)
Voltage gated
opens or closes in response to membrane potential
Threshold potential
the membrane potential where voltage gated sodium channels open in a domino effect; about -55 mV
Repolarization path
Potassium channels open up and Na channels close
potassium is rushing out to make negative again
Absolute refractory period
new action potential will not initiate
Na channels cannot open immediately
Ca2+ voltage gated channels
Taken up in vesicles
neurotransmitters either undergo degradation or reuptake
Membrane resistance
ability to keep charges separate
high membrane resistance= effective action potential transmission
Cytoplasmic resistance
How much the cytoplasm itself impedes the flow of ions
more resistance= less conduction
Larger neuron= less resistance
Larger neurons
lower cytoplasmic resistance
higher capacitance
faster at conducting signals
harder to depolarize
Smaller neurons
higher cytoplasmic resistance
lower capacitance
slower at conducting signals
easier to depolarize
Myelination
prevent reflux
increases membrane resistance
decreases capacitance
conduction is extremely rapid
Nerst equation
Ecell=E0 - lnQ x RT/nF
natural log of 1
zero
Action potential
flow of ions
