Brain & Behavior Ch 4

Front 1

difference in electrical charge between the inside and outside of a cell

Back 1

membrane potential

Front 2

resting neurons are _____ because the ratio of negative to positive charges is greater inside the neuron than outside

Back 2

polarized

Front 3

a neuron's steady membrane potential

Back 3

resting potential

Front 4

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

Back 4

high, low

Front 5

ions pass through the neural membrane at specialized pores called ___

Back 5

ion channels

Front 6

mechanisms in the membrane of a cell that actively move ions or molecules across the membrane

Back 6

transporters (ex: sodium-potassium pumps)

Front 7

excitatory postsynaptic potentials (EPSPs) ____ the likelihood the neuron will fire

Back 7

increase

Front 8

inhibitory postsynaptic potentials (IPSPs) ____ the likelihood the neuron will fire

Back 8

decrease

Front 9

EPSPs and IPSPs are ___ ___, meaning the amplitudes of EPSPs and IPSPs are proportional to the intensity of the signals that elicit them

Back 9

graded responses

Front 10

ion channels that open or close in response to changes in the level of the membrane potential

Back 10

voltage-activated ion channels

Front 11

1 to 2 milliseconds after initiation of an action potential during which it is impossible to elicit a second one

Back 11

absolute refractory period

Front 12

period during which it is possible to fire the neuron again, but only by applying higher-than-normal levels of stimulation

Back 12

relative refractory period

Front 13

in myelinated axons, ions can pass through the axonal membrane only at the ___ _ ___, gaps between adjacent myelin segments

Back 13

nodes of ranvier

Front 14

the transmission of action potentials in myelinated axons is called ___ ___ because the signal "jumps" along the axon from node to node.

Back 14

saltatory conduction

Front 15

synapses of axon terminal buttons on dendrites

Back 15

axodendritic synapses

Front 16

synapses of axon terminal buttons on somas (cell bodies)

Back 16

axosomatic synapses

Front 17

axoaxonic synapses can either ___ or ___ the effects of that button on the postsynaptic neuron

Back 17

facilitate or inhibit

Front 18

synapses at which the site of neurotransmitter release and the site of neurotransmitter reception are in close proximity

Back 18

directed synapses

Front 19

synapses at which the site of NT release and reception are at some distance

Back 19

nondirected synapses

Front 20

large neurotransmitters are all ___, short amino acid chains comprising between 3 and 36 amino acids

Back 20

neuropeptides

Front 21

small neurotransmitters are synthesized in the cytoplasm of the terminal button and packaged in ___ ___ by the ___ ___

Back 21

synaptic vesicles, Golgi complex

Front 22

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

Back 22

ribosomes, microtubules

Front 23

many neurons contain two neurotransmitters, called

Back 23

coexistence

Front 24

the process of neurotransmitter release

Back 24

exocytosis

Front 25

neurotransmitter molecules produce signals in postsynaptic neurons by binding to ___ in the postsynaptic membrane (a protein that contains binding sites for only particular neurotransmitters)

Back 25

receptors

Front 26

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

Back 26

ionotropic receptor

Front 27

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

Back 27

metabotropic receptor

Front 28

___ receptors induce an immediate postsynaptic potential

Back 28

ionotropic

Front 29

___ receptorsare more prevalent, have slower effects that are longer-lasting, more diffuse, and more varied

Back 29

metabotropic

Front 30

metabotropic receptors that bind to their neuron's own neurotransmitter molecules and are located on the presynaptic membrane

Back 30

autoreceptors

Front 31

majority of neurotransmitters are almost immediately drawn back into the presynaptic buttons by transporter mechanisms; this is called ___

Back 31

reuptake

Front 32

some neurotransmitters are broken apart in the synapse by proteins that stimulate or inhibit biochemical reactions w/o being affected by them

Back 32

enzymatic degradation

Front 33

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

Back 33

gap junctions (electrical synapses)

Front 34

drugs that facilitate the effects of a particular neurotransmitter

Back 34

agonists

Front 35

drugs that inhibit the effects of a particular neurotransmitter

Back 35

antagonists

Front 36

antagonistic drugs that bind to postsynaptic receptors without activating them and block the access of the usual neurotransmitter

Back 36

receptor blockers

Front 37

occurring naturally within the body

Back 37

endogenous

Front 38

___ are a major family of endogenous opioids

Back 38

endorphins