• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/106

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

106 Cards in this Set

  • Front
  • Back
T/F
Electrical synpases are specific to nervous tissue.
FALSE.
what are electrical synapses?
They are specialized modifications of the membranes between two adjacent cells that allow a direct transfer of small molecules.
what are the two primary types of electrical synapses?
ephaptic connections and gap junctions
what are ephaptic connections?
is a special area of the cell membrane (usually the epithelia) where there is an area of low resistance and contact can allow the exchange of ions between cells.
In what type of glial cells are ephaptic connections most common?
in astrocytes
what do ephaptic connections allow areas of the epithelia to do?
maintain a uniform layer of cellular potential between tissues and a lumen.
what are connexons?
two mirror-image symmetric components that comprise gap junctions membranes
what are connexons comprised of?
hexamers of connexin subunit
in the nervous system, what are gap junctions?
small regions closely apposed cell membranes containing channels comprised of connexons.
what are the gap junction channels permeable to?
Na, K, Ca and small metabolites up to 1,000 MW
T/F

In response to large voltage differences between cells, Gap junctions may open and close.
TRUE!
they do exhibit some ionic and directional selectivity.
where do typical gap junctions occur between? (6)
astrocytes, oligodendrocytes, schwann cell in the PNS, cells of the meninges, ependymal cells linings the ventricles and between cell types.
what type of junctions may help to define the synchronous development of groups of cells?
Gap
what kind of coupling usually accompanies gap junctions?
rapid transmission that appears to contribute to organized oscillatory or rhythmic activity of nuclei
what are three given pathologies that are associated with Gap junctions?
seizures, spreading depression and migraine headaches.
what is charcot-marie-tooth disease?
a common hereditary peripheral neuropathy that relates to mutations in the gene for connexins resulting in demyelination and slowing of conduction in peripheral axons.
what do neurotransmitter synpases require in order to be converted to a chemical signal?
electrical signal (AP)
what can chemical neurotransmission do that electrical cannot?
create a much more complex system of information processing.
what are the three primary elements of a chemical synapse?
presynaptic element (bouton), synaptic cleft, and postsynaptic element
what is the sequence of neurotransmission?
1)presynaptic bouton- vesicle synthesis and loading with transmitter and the transport to the synaptic terminal, depol of terminal and release of neurotransmitter into synaptic cleft. 2) postsynaptic membrane- binding of the transmitter to and activation of a receptor. Transduction of the signal by the postsynaptic cell. 3) pre and post synaptic - reuptake or degradation of the neurotransmitter
how is electrical to chemical transduction accomplished?
via vesicular release of neurotransmitter.
at what mV is the threshold for voltage sensitive calcium channels in a glial cell?
200
what does the increase in calcium initiate? (in regards to vesicle fusion and transmitter release) via what mechanism?
vesicle release; docking (binding) of synaptic vesicle to protein complexes
what is the calcium sensitive protein that is added to the complex in order to aid in the release of the neurotransmitter?
synaptotagmin
What molecule controls the release of the neurotransmitter into the synaptic cleft?
calmodulin
what are the two proteins involved in vesicle membrane recycling?
dynamin and clatharin
what is the kiss and run?
when vesicles detach after fusion
what do the recycled vesicle membranes become?
reincorporated into new synaptic vesicles
T/F
For small molecule transmitter, the vesicles are then reloaded within the terminal and recycled.
FALSE

they are reused, not recycled.
T/F
All neurotransmitters are released at the synaptic junction or by vesicular release.
FALSE

some, like catecholamines and neuropeptides, may be released from varicosities along axons through diffusion and into ECS
peripheral autonomic axons use what type of release for their neurotransmitter?
the release from varicosities along axons through diffusion and into the extracellular space.
why are small molecule neurotransmitters potentially sensitive to agents when can interfere with synthetic or recycling enzymes?
because they undergo extensive recycling and synthesis within the presynaptic terminal
where are large molecule neurotransmitters synthesized?
golgi apparatus
how are large molecule neurotransmitters transported? where to?
via fast axoplasmic transport to the nerve terminal
what else can be released in conjunction with small neurotransmitters?
neuropeptides
what are the five types of classification by function?
ligated channels, G-protein coupled (other second messengers), transmembrane receptors with modifiable enzymatic activity, ligand, and sequestration of intracellular ions.
what are the two primary categories of synapses based on postsynaptic transduction mechanisms?
ionotropic synapses and metabotropic synapses
describe ionotropic synapses
includes small molecule synapses, fast synapses, single messenger synapses. Activate primarily ionotropic receptors.
describe metabotropic synapses
includes larger neuropeptide synapses (>10 C), slow synapses, second messenger synapses. Activates primarily metabotropic receptors.
T/F
Synapses can be mixed.
True :)

a single transmitter may activate multiple types of receptors.
ionotropic receptors fit into which classification by function?
ligated ion channels
T/F
ionotropic synapses are relatively difficult to activate
FALSE

relatively easy
what is the basic advantage of the second messenger systems?
the ability to magnify the transduction and regulate the postsynaptic cell
about 75% of metabotropic receptors initiate transduction through what protein? what allows the coupling of the receptor to a G-protein?
G-protein; neurotransmitter binding to the receptor
what are the most common second messenger systems?
adenylyl cyclase, phospholipase C and phospholipase A
what does adenylyl cyclase produce as a second messenger? phospholipase C? phospholipase A?
1) cAMP, 2) IP3 and DAG, and 3) arachiodonic acid cascade
name all of the steps of the cAMP system through the opening of a channel.
an activated receptor causes the release of G protein which binds GTP and then adenylate cyclase. This activated enzyme converts ATP to cAMP. cAMP converts Protein kinase A to phosphorylate the sodium channel allowing it to open.
what inhibits the opening of the sodium channel in the cAMP system?
phosphatase
name all of the steps of the phosphoinositol system through the opening of a channel.
G-protein GTP complex activates phospholipase C which splits the phospholipid into two: DAG and IP3. DAG activates protein kinase C which does a lot of protein phosphorylation and IP3 opens SER calcium channel.
what are the two primary mechanisms involved in the rapid removal of the transmitter form the synaptic cleft?
inactivation and reuptake
what actually destroys/ modifies the neurotransmitter during inactivation?
the membrane bound enzymes around the synaptic cleft. They can be located on the post-synaptic membrane, adjacent astrocytes or on the presynaptic membrane
T/F
the enzymes involved in inactivation of the neurotransmitter typically cleave the transmitter into smaller, inactive but recycleable parts.
TRUE!!!!
where are most neurotransmitters or their inactivated products directly taken up by transporter proteins?
on the presynaptic membrane and on adjacent neuroglial cells
what are the enzymes that inactivate and release catecholamines?
monoamine oxidase and catechol-O-methyl transferase
T/F
There are no receptors on neuroglial cells.
FALSE
what do the receptors of neuroglial cells modulate?
neuroglial control of synaptic environmet (including neuroglial inactivation and recycling of transmitters and balance of ions in the EC environment)
astrocytes are particularly active in the regulation and control of ______ and _______
glutamate and GABA
what is retrograde transmission?
process of feedback from the postsynaptic cell.
how does the postsynaptic cell respond to synaptic activation in retrograde transmission?
by releasing a second chemical messenger capable of affecting the presynaptic nerve terminal or neuron.
Give an example of a retrograde neuromodulator.
Nitric oxide
where are the receptors located in presynaptic autoregulation? what is being regulated?
on the presynaptic membrane for the same neurotransmitter. The neurotransmitter being released and the other substances that go along with it are being regulated.
what is the job of the receptors in presynaptic autoregulation?
to make information transfer more efficient
T/F
The receptors of presynaptic autoregulation are generally inhibitory.
TRUE
T/F
The autonomic regulation of the sinoatrial node of the heart is an example of presynaptic autoregulation.
TTTRRRUUUUEEE
In adults as well as development, the retrograde transport of materials back to the cell body of a neuron is an essential part of what?
the maintenance of connections between a neuron and its target cell.
After exposure to a neurotransmitter of an agonist substance, what will regulate the responsiveness of the cell to it?
changes in receptors
how is receptor regulation generally accomplished?
through metabotropic mechanisms
what is the process of desensitization?
involves a short time frame in which the sensitivity of the receptor may be affected by chemical modification. The binding of the neurotransmitter may make it more susceptible to the intracellular enzymes that modify the receptor. Phosphorylation may either change the binding or transduction properties of the receptor to make it less efficient.
what is homologous desensitization?
desensitization produced directly from process of receptor activation
what are the two ways in which desensitization can be produceD?
homologous desensitization or by indirect means through the activation of phosphorylation by other means
how can the actual number of receptors be altered? if the receptor number decreases what is it called? increases?
by increasing the degradation of the receptor and/or the transcription or degradation of its mRNA. downregulation and upregulation
what is denervation supersensitivity?
a particular case of upregulating in which the loss of neuronal contact with a cell may result in the cell synthesizing and being exposed a larger than normal number of receptors making the cell super- sensitive.
what are five major groups neurotransmitters?
amino acids, biogenic amines, neuropeptides, purines and gaseous
what are the neurotransmitters of the amino acid group?
glutamate, GABA and glycine
what are the neurotransmitters of the biogenic amines?
acetylcholine, monoamines- catecholamines, dopamine, norep, epi, serotonin, histamine
what are the neurotransmitters of the neuropeptides
VIP, substance P, enkephalins, endorphins, orexin, oxytocin, and vasopressin
what are the neurotransmitters of the purines?
adenosine, ATP
what are the neurotransmitters of the gaseous?
nitric oxide, carbon monoxide.
what is the most prevalent excitatory transmitter in the CNS?
glutamate
what is the derivative of glutamate?
alpha ketoglutarate
what is the precursor for GABA?
alpha ketoglutarate via GABA transaminase
via which transporter is glutamate recycled?
both directly into presynaptic terminals for reuse and indirectly through astrocytes.
what happens when glutamate is indirectly recycled by astrocytes?
it is degradaed into glutamine and then reconverted to glutamate.
what is the primary inhibitory neurotransmitter in the brain?
GABA
where in the brain is GABA found in high amounts?
striatum and lentiform nuclei, hypothalamus, hippocampus, periaqueductal gray and is the transmitter for purkinje cells of the cerebellum.
where is glycine primarily located?
brainstem and spinal cord
T/F
glutamate and glycine are both excitatory neurotransmitters
FALSE

glycine is an inhibitory neurotransmitter
what mechanisms are primarily associated with glycine?
recurrent inhibition
via what type of transporter is glycine recycled?
an active transporter
which neurotransmitter has both excitatory and inhibitory properties with both ionotropic and metabotropic receptors?
acetylcholine
what are the two precursors of acetylcholine?
choline and acetyl CoA
what is acetylcholine broken down to? via which enzyme
choline and acetic acid; acetylcholinesterase
where does the choline and acetic acid from the acetylcholine go?
they are transported into the terminal and recycled.
which group of neurotransmitters is both excitatory and inhibitory and is synthesized from tyrosine?
catecholamines
what are the neurotransmitters that fall under the category of catecholamines?
dopamine, norepi and epi
what is the major enzyme involved in inactivation and recycling on the post synaptic membrane? presynaptic membrane?
Catechol-O-methyl transferase and monoamine oxidase
what neurotransmitter is both excitatory and inhibitory and synthesized from tryptophan?
serotonin
what are some of the jobs that serotonin is responsible for?
sleep/wake cycles, emotional behavioral states and a prominent component of platelets (vasoconstriction)
when serotonin is broken down, where does it go?
back into the presynaptic terminal
would you prescribe a drug that inhibited the reuptake of serotonin on someone who was having hallucinations?
yes
which neurotransmitter is excitatory and a component of mast cells?
histamine
what is histamine a component of?
mast cells and basophils and involved in gastric secretion
what is the histamine that is similar to serotonin?
sleep/wake cycles and the maintenance of a conscious state
All neuropeptides are ______tropic and _______ coupled
metabo-, G-protein
where in the brain are neuropeptides prominent? (3)
hypothalamus, brainstem and basal ganglia
beyond autonomic functions, substance P, b-endorphin and enkephalin are involved in what?
transmission of pain and pleasure sensations.