Membrane Potential

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