Shared Flashcard Set

Details

synaptic transmission
lecture chapter 12
48
Anatomy
Undergraduate 1
05/07/2010

Additional Anatomy Flashcards

 


 

Cards

Term
synapse
Definition
a juction between 2 neurons across which a nerve signal is conducted
Term
pre-synaptic neuron does what?
Definition
conducts information to synapse
Term
post-synaptic neuron does what?
Definition
conducts information away from synapse
Term
synaptic cleft
Definition
separation between synaptic knob of presynaptic neuron and membrane of post synaptic neruon
Term
how many synapses may a single neuron in the cerebellum have?
Definition
100,000
Term
synapse may be 3 things axo-?
Definition
axodendritic, axosomatic, axoaxonic
Term
electrical synapse
Definition
when a nerve signal is transmitted by flow of ions from one cell to another through gap juctions
Term
function of electrical synapse
Definition
allow fast communication, synchronization among multiple neurons or muscle fibers, two-way transmission of signals
Term
chemical synapse
Definition
nerves signal is transmitted by small organic transmitters
Term
4 things neurontransmitters bo in chemical synapes
Definition

-neurontransmitters is synthesized by pre-synaptic neuron and stored in vesicles

-are released frim pre-synaptic neuron in response to stimulus

-bind to specific receptors on post-synaptics neurons

-alter physiology of post-syanptic neuron

Term
how many substances can be classified as neurotrasmitters
Definition
over 100
Term
neurotransmitter acetycholine (Ach)
Definition
most familiar and can be excitatory or inhibitory
Term
amino acids as neurotransmitters
Definition
can be excitatory of inhibitory
Term
biogenic amines as neurotrasmitters
Definition
are modifies amino acids that may be excitatory or inhibitory
Term
neuropeptides as neurotransmitters
Definition
amino acid chains that may be excitatory or inhibitory
Term
neuropeptides as neuromodulators
Definition
some are and function like hormones
Term
neuropeptides may be responsible for what?
Definition
craving fat and/or sugar and may cause some eating disorders
Term
achetylcholine is the neurotransmitter where?
Definition
at an excitatory cholenergic synapse
Term
what does the arrival of a nerve signal at a pre-synaptic knob do?
Definition
opens voltage-gated calcium channels
Term
what is the role of Ca+2 ot an exitatory cholinergic synapse?
Definition
Ca+2 enter pre-synaptic knob and trigger exocytosis of synaptic vesicles that release Ach into synaptic cleft
Term
what happens to the empty vesicles after the Ach has been released into synaptic cleft?
Definition
empty vesicles are refilled with Ach
Term
where does Ach diffuse after being released into synaptic cleft?
Definition
diffuses across synaptic cleft and binds with recpetors on postsynaptic membrane
Term
what happens when ligand-regualted gates open?
Definition
Na+1 enter post-synaptic neuron, K+1 leaves post-synaptic membrane
Term
what may happen as a reseult of the postsynaptic potential?
Definition
may trigger action potential if it is strong enough to depolarize post-synaptic membrane to threshold
Term
what neurontransmitter is at an inhibitory synapse?
Definition
GABA
Term
how does GABA work?
Definition
like Ach, except it opens chloride channels and hyper polarizes post-synaptic membrane making it harder to generate action potential
Term
what neurotrasmitter is at an excitatory adrenergic synapse?
Definition
Norepinephrine
Term
how does norepinephrine work?
Definition
operates by second-messenger system that activates transmembrane G protein binding it to adenylate cyclasm
Term
adenylate cyclase
Definition
catalyzes conversion of ATP to cAMP
Term
cAMP does 3 things..
Definition

-binds to ligand-regualted ion gat on inside of membrane and opens it to depolarize membrane

-activates cytoplasmic enzymes that catalyze changes in metabolic reactions

-also induces transcription

Term
what must happen to stop the transmission of nerve signals?
Definition
neurotransmitters must be removed from synaptic cleft
Term
how can neurotrasmitters be removed from a synaptic cleft? [3]
Definition

-they can diffuse out of synaptic cleft into ECF where they get absorbed by astrocytes to be returned to the pre-synaptic neuron

-they can be actively transported back into neuron that released them

-Ach can be degenerated by acetylcholinesterase

Term
postsynaptic potential
Definition
grade potentials whose size varies according to strength of stimulus and amount of neurotransmitter that was released
Term
when does excitartoy postsynaptic potential (EPSP) occur?
Definition
if neurotrasmitter causes depolarization of post-synaptic membrane because Na+1 flow into cell
Term
what is membrane potential with EPSP?
Definition
it approaches threshold, so neuron is more easily stimulated
Term
when does inhibitory postsynaptic potential (IPSP) occur?
Definition
it neurotransmitter causes hyperpolarization of post-synaptic membrane, if Cl-1 flow into cell or if K+1 flow out of cell
Term
what is membrane potential with IPSP?
Definition
moves away from threshold, so neuron is harded to stimulate
Term
summation
Definition
all postsynaptic potentials are added together and whether post-synaptic neuron fires depends on NET input of EPSP's and IPSP's
Term
what is a typical EPSP?
Definition
it is too weak and short lived to depolarize membrane to threshold
Term
where does a temporal summation occur?
Definition
at single synapse because each EPSP is generated at such a short interval that previous EPSP hasn't decayed
Term
consequences of temporal summation
Definition
if enough EPSPs are generat to depolarize post-synaptic membrane to threshold, action potential is generated
Term
when does spatial summation occur?
Definition
when several pre-synaptic neurons generate EPSPs at the same time
Term
consequences of spatial summation
Definition
single synapse only allows small numbers of Na+1 into post-synaptics membrane, but if multiple synapses allow wnough Na+1 to enter and post-synaptic membrane is depolarized to threshold, action potential can be generated
Term
facilitation is when..
Definition
several neuron cooperate together to enhance effects on one onother
Term
what is pre-synaptic inhibition?
Definition
when one pre-synaptic neuron may supress another pre-synaptics neuron to halt transmission of nerve signal
Term
GABA and presynaptic inhibition..
Definition
GABA may be released, which prevents pre-synaptic neuron from releasing neurotransmitter into synaptic cleft
Term
neurotransmitter deficiencies [2]
Definition

-alzheimers disease

-parkinson disease

Supporting users have an ad free experience!