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Electrical transmission uses ___ _______ across the membrane to generate electrical potentials
ion channels
In chemical transmission, 2 neurons are not directly connected.. one neuron releases ________ _________ at the terminal which act on the next neuron through receptors to initiate an electrical signal
chemical messengers
ion channels are usually _______, meaning when they are open, ion movement is along the concentration gradient.
passive
ion channels can be _____ ______, meaning they open when the membrane reaches a given potential
voltage gated
Na+/K+ ATPase pump use ___ to move ions _____ their concentration gradients
ATP, against
ion channels that open when ligand bind to the receptor on the surface:
ligand gated
Intracellular Na+ and Cl- is ______, while extracellular K+ is _____.
high, low
A means of calculating the equilibrium potential of a given ion across the membrane
nernst equation
resting membrane potential:
-70 mv
Resting membrane potential is primarily driven by the flux of __ out of the cell down its concentration gradient through ____ __ channels
K+, leak K+
The Na+/K+ ATPase pump maintains the negative membrane potential by actively pumping __ out of he cell and __ into the cell against their concentration gradients
Na+, K+
Moving the membrane potential from negative toward zero
depolarization
The polarization of the membrane from zero to a positive
overshoot
Going back to the negative resting membrane potential
repolarization
Going more negative than the resting membrane potential
hyperpolarization
First step of action potential (rise)
Na+ channels open, Na+ enters cell
Second step of action potential (top of peak)
K+ channels open, K+ begins to leave cell, Na+ channels close
Third step of action potential (fall)
K+ channels close
Last step of action potential (leveling out)
Excess K+ outside diffuses away
Sodium channels open and inactivate very _____
rapidly
Potassium channels open and close _____
slowly
A period of time during which a second stimulus cannot induce a new action potential
absolute refractory period (Na+ channels cannot re-open)
A period of time after the absolute potential can be induced but requires a stronger stimuli
relative refractory period (some, but not all Na+ channels have returned to their resting state)
Saltatory conduction - action potentials only occur at ______ __ _______
nodes of Ranvier
Saltatory conduction - implies jumping of AP, but it doesn't actually jump it _______ __ ____ ____
regenerates at each node
Saltatory conduction means ________ __________ is much faster than an unmyelinated axon.
signal propagation
Synaptic transmission involves... (3)
neurotransmitter molecules, synapse, receptor
This type of signal allows information from many different sources to influence a cell's activity
convergence
This type of signal allows one cell to influence multiple pathways
divergence
The ________ terminal contains synaptic vesicles, which hold the neurotransmitter.
presynaptic
The ________ ______ is a 10-20nm space between the cells
synaptic cleft
The __________ _______ is populated with receptors, which allow the initiation of the new action potential in the receiving cell
postsynaptic density
Synaptic transmission - _____ ______ triggers release of neurotransmitters
action potential
Activation of the postsynaptic cell involves _ proteins
G (metabotropic)
The binding of a ligand (the neurotransmitter) to the receptor opens the ion channel
ionotropic
The binding of a ligand to the receptor activates a SECOND MESSENGER protein, a G protein, which can either directly activate an ion channel or activate an intracellular signaling cascade which will activate an ion channel
metabotropic
(ionotropic vs. metabotropic) Bottom line: most of the time, _____ ______ opens ion channels
receptor activation
Negative interior of cell, means that it is ____polarized
hyper
Positive interior of cell, means that it is ____polarized
de
EXCITATORY SYNAPSES usually involve the opening of __ or __ channels
Na+ or Ca2+
INHIBITORY SYNAPSES usually involve the opening of __ or _ channels
Cl- or K+
A change in membrane potential relative to resting potential is known as a _______ _________
graded potential
The potential changes in the membrane that occur at an excitatory synapse (depolarize - Na+ channels)
excitatory postsynaptic potentials (EPSP)
The potential changes that occur at an inhibitory synapse (hyperpolarize - Cl- channels)
inhibitory postsynaptic potentials (IPSP)
Synaptic integration - temporal means
time
Synaptic integration - spatial means
2 different synapses fired
Neurotransmitters are all VERY DIVERSE, YET ALL CLASSIFIED AS NEUROTRANSMITTERS. Ok?
Ok
Ach is inhibitory or excitatory?
excitatory
Glutamate is inhibitory or excitatory?
excitatory
GABA is inhibitory or excitatory?
inhibitory

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