lab 10 Flashcards
why are drugs that act on the CNS invaluable therapeutically?
bc they can produce specific psychological and physiological effects
drugs that affect the CNS can,,,,,
selectively relieve pain, reduce fever, suppress disordered movements, induce sleep or arousal, reduce the desire to eat, or allay the tendency to vomit
______ allows modern surgery to be possible
general anesthetics
in the CNS, receptors to most synapses are coupled to what?
ion channels
what are neurotransmitters?
chemical messengers that bind to postsynaptic membrane receptors.
results in a RAPID and TRANSIENT opening of ion channels which allows ions to move inside and outside of the cell membrane
what occurs when ions move into/out of the cell membrane?
this alters the postsynaptic resting membrane potential which generates an ACTION POTENTIAL
how can neurotransmitters be classified
either as excitatory or inhibitory (depending on the nature of the action)
the stimulation of EXCITATORY neurons causes what?
the movement of sodium ions into the membrane, resulting in DEPOLARIZATION of the postsynaptic membrane
this EPSP (excitatory postsynaptic membrane potential) leads to the generation of an action potential
when inhibitory neurons are stimulated, what occurs?
a movement of CHLORIDE ions into the cell membrane and/or POTASSIUM ions OUT of the cell membrane
this causes HYPERPOLARIZATION of the postynaptic membrane. IPSP generated which BLOCKS the generation of an action potential if the resting potential becomes too negative
true or false
most neurons in the CNS receive only IPSP input
false – both EPSP and IPSP input
most neurons in the CNS receive both IPSP and EPSP input.
thus….
several neurotransmitters may act on the same neuron, but each to its own specific receptor
true or false
only 1 neurotransmitter can act on a neuron at a time
FALSE
most neurons receive both EPSP and IPSP input, thus SEVERAL neurotransmitters may act on 1 neuron, but each to their own specific receptor
name 3 drugs that cause hyperpolarization
GABA
barbiturates
chlorpromazine
name 2 drugs that cause depolarization
caffeine
PTZ
drugs that cause hyperpolarization are called ______ and generate ____
depressants
generate IPSP
drugs that cause depolarization are called ___ and generate ____
stimulants and generate EPSP
in hyperpolarization, what ions are moving?
chloride into the cell and/or potassium out of the cell
give the mV during hyperpolarization
-90mv
give the mv of the normal resting membrane
-65 - -70mv
give the mV of a depolarized membrane
+30mv
what ions are moving in depolarization
sodium comes in, and after the sodium channel closes, potassium goes out of the cell
neurotransmitters can produce how many types of impulses?
name them
2
EPSP - excitatory postsynaptic potential
IPSP - Inhibitory postsynaptic potential
dopamine and ____ generate an ____
acetycholine
EPSP
GABA and _____ generate an _____
serotonin
IPSP
EPSP results in and initiates….
IPSP results in and initiates…
EPSP results in depolarization and the initiation of an action potential
IPSP results in hyperpolarization and the INHIBITION of an action potential
___ and ____ generate an EPSP
dopamine and acetylcholine
___ and ___ generate an IPSP
GABA and serotonin
EPSP controls the ___ of ___ ions
inflow of sodium ions
IPSP controls the ___ of ___ ions
outflow of potassium ions
inflow of chloride ions
what is dopamine?
a neurotransmitter that is released in the DOPAMINERGIC neurons
generates an EPSP, leading to EXCITATORY EFFECTS
Name an antagonist that competes with dopamine and what they can be used as
CPZ - chlorpromazine is an antagonist to dopamine at the D2 receptors
can be used as neuroleptic agents
give 3 components of the neuroleptic response of CPZ (chlorpromazine)
- decreases agitation
- drowsiness
- dizziness
true or false
caffeine is a stimulant
true
caffeine is a ___ antagonist
adenosine
how is caffeine a stimulant?
it further enhances excitatory effects by affecting various receptors in the neuron that are responsible for dopamine levels in synapse and blood stream
IT INCREASES DOPAMINE LEVELS
what does adenosine do
it controls the release of dopamine
does this by binding to the adenosine receptor at the axon terminal and REDUCES dopamine release
explain how caffeine is an antagonist to adenosine
caffeine binds to adenosine receptors and thus causes dopamine to be released and dopamine receptors to open up for binding
(adenosine inhibits the release of dopamine and caffeine does the opposite)
what does GABA stand for
gamma-aminobutyric acid
what is GABA
a neurotransmitter released in GABA-aminergic neurons
acts to generate an IPSP
true or false
GABA is a neurotransmitter that acts to generate an EPSP
FALSE IPSP
how does GABA generate an IPSP
when GABA binds to 2 possible receptors – GABA-A and GABA-B
what are the overall effects when GABA binds to GABA A or GABA B
sedation
anxiolytic
muscle relaxation
anti-seizure
name 2 GABA agonists and explain how they work
barbiturates and benzodiazepines
they will enhance the effect, but ONLY WHEN GABA IS PRESENT
name a GABA antagonist
PTZ (pentylenetetrazole)
explain how PTZ is a GABA antagonist
antagonizes the effects of GABA due to competition at the receptor site
stimulates the CNS
explain the GABA A receptor and the GABA B receptor
GABA A = ligand gated ion channel - ionotropic - forms Cl- channel
GABA B = GPCR
binding to the GABA A receptor results in…
increased Cl- conductance
causes sedation, anxiolytic activity, muscle relaxation, and anti seizure
binding to GABA-B receptor and g protein results in…..
K+ conductance
inhibitory in nature
name a GABA antagonist
PTZ (pentylenetetrazole)
true or false
barbiturates are GABA agonists and result in IPSPs
true
tonic vs clonic convulsion
tonic = all paws are extended
clonic - front and rear paws drawn in and extended out alternately
what is the antidote for convulsions caused by PTZ
2x dose of pentobarbital
