Nervous System Flashcards

Flashcards about the Nervous System

Dendrites

Branches that receive incoming signals

Soma (Cell Body)

Contains the nucleus and organelles

Axon Hillock

Where the action potential begins

Axon

Long fiber that carries electrical signal away from the soma

Axon Terminals

Ends of the neuron where neurotransmitters are released

Resting Membrane Potential

Electrical charge across the membrane when not active (about -70 mV)

Sodium-Potassium ATPase

Pump that moves 3 Na out and 2 K in to maintain resting potential

Ion Gradients (Na, K)

More Na outside, more K inside; drives electrical activity

Graded Potentials

Small, local changes in membrane voltage

Depolarization

Membrane potential becomes more positive

Hyperpolarization

Membrane potential becomes more negative

Repolarization

Return to resting potential after depolarization

Action Potential

Rapid electrical signal sent down an axon

Threshold

Minimum voltage required to trigger an action potential

All-or-None Principle

Action potential fires fully or not at all

Refractory Period

Time when neuron can't or is less likely to fire again

Leak Channels

Always open, allow passive ion movement

Chemically Gated Channels

Open when neurotransmitter binds

Voltage-Gated Channels

Open when membrane voltage reaches a threshold

Mechanically Gated Channels

Open when physically deformed

Electrical Synapse

Direct connection between cells via gap junctions

Chemical Synapse

Signal sent using neurotransmitters across a synaptic cleft

Synaptic Delay

Brief pause as neurotransmitter crosses the synapse

Synaptic Fatigue

Depletion of neurotransmitter after overuse

Excitatory Neurotransmitter

Increases chance of action potential (e.g., glutamate)

Inhibitory Neurotransmitter

Decreases chance of action potential (e.g., GABA)

Direct Effect

Neurotransmitter directly opens ion channels

Indirect Effect via G Protein

Neurotransmitter triggers second messenger pathway

EPSP

Excitatory postsynaptic potential; small depolarization

IPSP

Inhibitory postsynaptic potential; small hyperpolarization

Temporal Summation

Repeated signals from same source over time

Spatial Summation

Simultaneous signals from multiple sources

Presynaptic Inhibition

Reduces neurotransmitter release

Presynaptic Facilitation

Increases neurotransmitter release