Neural Communication Flashcards
electrical from dendrite to
terminal
chemical from terminal to
dendrite
when the cell is at rest
slight negative charge
resting potential
membrane potential
at rest- intracellular fluid
around -70mV
K+ & organic anions
at rest- positive charge
Na+ & Cl-
sodium potassium pump
regulate the exchange of sodium (into the cell) and potassium (gets pushed out)
ions
molecules with a charge
want to be evenly distributed
cell membrane keeps
Na+ & Cl- out of the cell
A- & K+ inside the cell
sodium potassium pump allows
Na+ & K+ to travel into & out of the cell
when the neuron is stimulated
ion channels open
Na+ rushes into the cell because of electrostatic pressure
depolarization
depolarization
sodium ion channels open
Na+ rushes into the cell
charge becomes less negative
later K+ channels also open- - K+ leaves the cell
action potential
the cell fires- sending a signal down the axon
starts at the hillock
repolarization
Na+ pushed OUT of cell
K+ continues to leave
charge becomes more negative
hyperpolarization (refractory)
K+ are retrieved from extracellular fluid
cell returns to resting state
cerebral neurons work differently
many fire continuously- even without input
action potentials of different cells vary in:
amplitude
duration
frequency
many neurons have no
axons (or action potentials)
dendrites of some cerebral neurons
conduct action potentials
language between neurons
chemical
neurotransmitters
binding site
a neurotransmitter will fit into a postsynaptic receptor like a key into a lock
ligand
a chemical that fits a binding site of a receptor
agonists
enhances the effects of NT on the postsynaptic cell
antagonists
inhibits NT effects on the postsynaptic cell
postsynaptic potentials
can be either depolarizing (excitatory) or hyperpolarizing (inhibitory)
this is not determined by the NT- but by the receptor site (the kind of ion channel they open)
both are caused by the release of NT from a nearby terminal button
sodium-potassium channel
ion specific (just one kind)
Na+ channels & K+ channels
Electrostatic pressure and diffusion
sodium-potassium pump
transport different kinds of ions in opposite directions across cell membranes
have a 3:2 ratio of Na+ & K+
active transport proteins (ATP)
excitatory postsynaptic potentials (EPSP)
an excitatory depolarization of the postsynaptic membrane
inhibitory postsynaptic potentials (IPSP)
an inhibitory hyperpolarization of the postsynaptic membrane
termination of postsynaptic potentials
reuptake
enzymatic deactivation
reuptake
the NT is reabsorbed by the terminal button
moved by transporter molecules
enzymatic deactivation
an enzyme destroys the molecules of the NT
ionotropic receptors
receptors are couple to ion channels
when the ion binds to the receptor, it causes the channel to open
sometimes…
receptor opens a channel that causes (+) charged particles to enter
more likely to have an action potential (excitatory)
other times…
receptors open ion channels that make (-) charged ions to enter the cell
more difficult to produce an action potential (inhibitory)
metabotropic
slow receptors (delayed by milliseconds)
can be long lasting
they are not tied to an ion channel
the activation/release of G proteins
effects of G proteins
can act like an ionotropic receptor
can initiate synthesis of AMP (adenosine monophosphate)
second messengers
neurochemical mechanisms of drug action
drug effects can operate on the nervous system in a variety of ways
neurotransmitter synthesis
increase or decrease the synthesis of neurotransmitters
neurotransmitter transport
interfere with the transport of neurotransmitter molecules to the axon terminals
neurotransmitter storage
interfere with the storage of neurotransmitters in the vesicles of the axon terminal
neurotransmitter release
cause the axon terminals to release neurotransmitter molecules into the synapse prematurely
neurotransmitter degradation
influence the breakdown of neurotransmitters by enzymes
neurotransmitter reuptake
block the reuptake of neurotransmitters into the axon terminals
receptor activation
activate a receptor site by mimicking a neurotransmitter
receptor blocking
cause a receptor to become inactive by blocking it
acetylcholine (ACh)
highly involved in sensory systems and motor movement
generally excitatory
acetylcholine receptors
binds to more than one type of receptor
nicotine (agonist)- only binds to particular receptors
many NTs bind to ____ than one receptor type
MORE
monoamines
norepinephrine
dopamine
serotonin
norepinephrine
regulates hunger, alertness & arousal
dopamine
L-dopa (able to pass through blood-brain barrier)
coordinated motor movements
anticipation of pleasurable experiences
serotonin
found throughout the brain (and gut)
implicated in sleep & mood
90% of serotonin receptors are in the
gut
amino acid NTs
GABA
glutamate
GABA
one of the most abundant in the brain
the most significant inhibitory NT (generally)
causes the cells to hyperpolarize
when a GABAergic receptor site is active- it takes more excitatory NT to get the cell to depolarize (fire)
barbiturates and tranquilizers act on GABA
glutamate
major excitatory NT
learning & memory
drugs like ketamine & PCP act on glutamate receptors
