inactivation gates of Na⁺
While ________ channels are closed, cell is unresponsive to another stimulus.
K+
________ moves out of the cell making the cell membrane less positive (more negative)
Inactivation gate
________ in Na+ channel shuts when membrane sufficiently positively polarized.
NA⁺ K⁺
________- ATPase (sodium- potassium pump): transports 3 Na+ out for every 2 K+ moved in.
Voltage
________- gated K+ channels also open at threshold potential, but 1 msec later than Na+ channels.
Separates charge
________ by keeping different ions largely inside or outside the cell.
Depolarization
________: cell membrane less polarized and less negative relative to surrounding solution.
ion channel
Ligand- gated ________: open and close in response to ligands or chemicals.
Exocytosis
________ releases neurotransmitter into.
Saltatory conduction
________: action potential seems to "jump "from node to node.
Hyperpolarization
________: cell membrane more polarized and more negative.
Na+
________ rapidly diffuses into cell causing spike.
Oligodendrocytes
________ and Schwann cells make myelin sheath.
Plasma membrane
________ is not very permeable to cations and anions.
membrane potential
Resting ________: when neurons are not sending signals.
Synaptic signal
________ ends when neurotransmitter is broken down by enzymes or taken back into presynaptic cell for reuse.
Broad axons
________ provide less resistance and action potential moves faster.
Spatial summation
________: when two or more EPSPs or IPSPs are generated at one time along different regions of the dendrites and cell body, their effects sum together.
Temporal summation
________: two or more EPSPs arrive at same location is quick succession.
Equilibrium potential
________: no net movement due to opposing forces of chemical and electrical gradients.
Negative ions
________ within the cell are drawn to the positive ions arrayed on the outer surface.
Chemical synapses
________: neurotransmitter acts as signal from presynaptic to postsynaptic cell.
Electrical synapses
________: electric charge freely flows through gap junctions from cell to cell.
Voltage
________- gated ion channel: open and close in response to ________ changes.
Membrane potential
________: difference in charge inside and outside the cell.
membrane potential
All cells have a(n) ________.
Membrane potential
difference in charge inside and outside the cell
Resting membrane potential
when neurons are not sending signals
NA⁺/K⁺ -ATPase (sodium-potassium pump)
transports 3 Na+ out for every 2 K+ moved in
Ion specific channels
allow passive movement of ions
Electrochemical gradient
combined effect of electrical and chemical gradient
Equilibrium potential
no net movement due to opposing forces of chemical and electrical gradients
Depolarization
cell membrane less polarized and less negative relative to surrounding solution
Hyperpolarization
cell membrane more polarized and more negative
Excitable
capacity to generate electrical signals
Voltage-gated ion channel
open and close in response to voltage changes
Ligand-gated ion channel
open and close in response to ligands or chemicals
All-or-none
cannot be graded
Actively propagated
regenerates itself as it travels
Not continuous
gaps at nodes of Ranvier
Saltatory conduction
action potential seems to "jump" from node to node
Presynaptic cell
sends signal
Synaptic cleft and postsynaptic cell
receives signal
Electrical synapses
electric charge freely flows through gap junctions from cell to cell
Chemical synapses
neurotransmitter acts as signal from presynaptic to postsynaptic cell
Excitatory postsynaptic potential (EPSP)
brings membrane closer to threshold potential
Inhibitory postsynaptic potential (IPSP)
takes membrane further from threshold potential (hyperpolarization)
Synaptic integration
integrates multiple inputs to single neuron
Spatial summation
when two or more EPSPs or IPSPs are generated at one time along different regions of the dendrites and cell body, their effects sum together
Temporal summation
two or more EPSPs arrive at same location is quick succession