Synapses Flashcards
what are the two broad classes of synapses?
electrical and chemical
size of an electrical synaptic cleft?
3/5 nM
size of a chemical synaptic cleft?
20-40 nM
which synapse has synaptic continuity?
electrical
which synapse has gap junctions?
Electrical
which synapse has presynaptic and postsynaptic elements?
Chemical
what is the agent of transmission for an electrical synapse? chemical?
ionic current? neurotransmitters stored in vescicles
which synapse has a delay? how long is that delay?
chemical synapses have .3-5 ms delays
What is the direction of potential movement in electrical? chemical?
bi-directional, uni-directional
in a chemical synapse is the response excitatory or inhibitory? what about for an electrical synapse?
either or
always excitatory
what is the function of a connexon?
synaptic element that is aligned so pore can allow current flow (1.5-2 nM in size)
what are the benefits of an electrical synaps?
rapid, pure diffusion, but it is a simple behavior
which synapse form is the pre-dominant form for communication?
chemical
describe an axo-somatic synapse?
in between axon of presynaptic to soma of post-synaptic (IPSP)
describe an axo-dendritic synapse?
axon of pre to dendrite of post (EPSP) this is most common
describe axo-axonic synapse?
axon to axon, has no effect on ap controls how much neurotrasnmitter is released
advantages of chemical synapses?
complex behaviors, requires energy, synaptic delay
role of the pre-synaptic terminal?
synthesis, storage, and release of transmitter
role of post-synaptic terminal?
receptive process responsible for binding the transmitter to receptor and activation
where are neurotransmitters stored?
vescicles that protect them from enzymatic degradation
what is one quanta?
contents of 1 vescicle, usually a fixed number
what is one quanta of ACh
2000
explain the dale principle
a neuron will release the same neurotransmitter at all of its sites
explain the co-existence principle
some neurons can release more than one transmitter
describe the process of neurotransmitter release?
AP arrival opens calcium channels, calcium causes vesicles to fuse with membrane, transmitter is released by exocytosis into cleft
what is a post-tetanic potentiation?
increase in transmitter release after a high frequency train of APs
what happens to calcium channels after a high use of the nerve?
cacium channels become leaky
what enzyme synthesized ACh? what breaks it down?
choline acetyltransferase
acetylcholinesterase
what is GABA synthesized from?
Glutamate
are GABA and glycine inhibitory or excitatory?
inhibit
is glutamate an inhibitory or excitatory transmitter?
excitatory
significance of glutamate?
precursor to GABA
what is used to synthesize serotonin?
tryptophan
what kind of food is tryptophan found in?
nuts, cheese, red meat
what can happen with a tryptophan deficiency?
anxiety and depression
what are three types of catecholamines?
norepinephrine, epinephrine, dopamine
what is needed for catecholamines?
tyrosine
what produces catecholamines?
adrenal medulla
T/F low levels of catechalomine circulation is associated with stress
false
what are the two main receptor functions?
recognizing transmitters and activation
what are directly gated receptors?
one molecule that does both the recognizing and activation (rapid)
what are indirectly gated channels?
different molecule for recognition function and activation function (slow but long lasting)
Name of the ACh directly gated and indirectly gated transmitter
directly; nicotinic
indirectly: muscularinic
what is the function of the nicotinic receptor and where is it located?
it opens both sodium and potassium but potassium over powers EPSP. neuromuscular junction
function and location of muscarinic receptor?
open/ close potassium can be IPSP or EPSP in PNS
what in the response to Glutamate regardless of type
EPSP. direct opens sodium indirect idk
does dopamine have indirect or direct terminals?
indirect either opens potassium or closes calcium (calcium opens vescicles)
Name of direct GABA terminals? indirect?
GABA A
GABA B
Effect of GABA A
opens chloride channels (IPSP)
Effect of GABA B
closes calcium (inhibition)
what does an agonist do?
binds to recognition portion and produces an effect
what does an antagonist do?
binds to recognition portion but fails to produce effect. it keeps other receptors from binding
how does acetylcholine become inactivated?
acetylcholine esterase breaks it into choline and acetate, sent back to presynaptic cleft
How do most transmitters get inactivated?
with energy they are reabsorbed by the presynaptic element
