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38 Cards in this Set

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  • Back
difference in electrical charge between the inside and outside of a cell
membrane potential
resting neurons are _____ because the ratio of negative to positive charges is greater inside the neuron than outside
polarized
a neuron's steady membrane potential
resting potential
ions are in constant random motion and are more likely to move down their concentration gradients than up them; therefore they will move from areas of ____ concentration to areas of ____ concentration
high, low
ions pass through the neural membrane at specialized pores called ___
ion channels
mechanisms in the membrane of a cell that actively move ions or molecules across the membrane
transporters (ex: sodium-potassium pumps)
excitatory postsynaptic potentials (EPSPs) ____ the likelihood the neuron will fire
increase
inhibitory postsynaptic potentials (IPSPs) ____ the likelihood the neuron will fire
decrease
EPSPs and IPSPs are ___ ___, meaning the amplitudes of EPSPs and IPSPs are proportional to the intensity of the signals that elicit them
graded responses
ion channels that open or close in response to changes in the level of the membrane potential
voltage-activated ion channels
1 to 2 milliseconds after initiation of an action potential during which it is impossible to elicit a second one
absolute refractory period
period during which it is possible to fire the neuron again, but only by applying higher-than-normal levels of stimulation
relative refractory period
in myelinated axons, ions can pass through the axonal membrane only at the ___ _ ___, gaps between adjacent myelin segments
nodes of ranvier
the transmission of action potentials in myelinated axons is called ___ ___ because the signal "jumps" along the axon from node to node.
saltatory conduction
synapses of axon terminal buttons on dendrites
axodendritic synapses
synapses of axon terminal buttons on somas (cell bodies)
axosomatic synapses
axoaxonic synapses can either ___ or ___ the effects of that button on the postsynaptic neuron
facilitate or inhibit
synapses at which the site of neurotransmitter release and the site of neurotransmitter reception are in close proximity
directed synapses
synapses at which the site of NT release and reception are at some distance
nondirected synapses
large neurotransmitters are all ___, short amino acid chains comprising between 3 and 36 amino acids
neuropeptides
small neurotransmitters are synthesized in the cytoplasm of the terminal button and packaged in ___ ___ by the ___ ___
synaptic vesicles, Golgi complex
neuropeptides are assembled in the cytoplasm on ___, are packaged in vessicles by the Golgi complex, and are then transported by ___ to the terminal buttons for release
ribosomes, microtubules
many neurons contain two neurotransmitters, called
coexistence
the process of neurotransmitter release
exocytosis
neurotransmitter molecules produce signals in postsynaptic neurons by binding to ___ in the postsynaptic membrane (a protein that contains binding sites for only particular neurotransmitters)
receptors
receptors that are associated with ligand (a molecule that binds to another)-activated ion channels; when NT binds to it, channels open or close, altering flow of ions
ionotropic receptor
receptors that are asociated with signal proteins and G-proteins; when NT binds to it, G protein breaks off into the neuron and either binds to an ion channel or stimulates synthesis of a second messenger
metabotropic receptor
___ receptors induce an immediate postsynaptic potential
ionotropic
___ receptorsare more prevalent, have slower effects that are longer-lasting, more diffuse, and more varied
metabotropic
metabotropic receptors that bind to their neuron's own neurotransmitter molecules and are located on the presynaptic membrane
autoreceptors
majority of neurotransmitters are almost immediately drawn back into the presynaptic buttons by transporter mechanisms; this is called ___
reuptake
some neurotransmitters are broken apart in the synapse by proteins that stimulate or inhibit biochemical reactions w/o being affected by them
enzymatic degradation
narrow spaces between adjacent neurons that are bridged by fine tubular channels that contain cytoplasm; thus the cytoplasm of the two molecules is continuous, allowing electrical signals and small molecules to pass from one neuron to the next
gap junctions (electrical synapses)
drugs that facilitate the effects of a particular neurotransmitter
agonists
drugs that inhibit the effects of a particular neurotransmitter
antagonists
antagonistic drugs that bind to postsynaptic receptors without activating them and block the access of the usual neurotransmitter
receptor blockers
occurring naturally within the body
endogenous
___ are a major family of endogenous opioids
endorphins