G7_Explorer_Synaptic Transmission and Amino Acid Neurotransmitters Flashcards
the most abundant neurotransmitters in the brain
Amino acids
Neurotransmitters are synthesized and stored in ____
presynaptic terminals
are specialized biological structures found in
the nervous system; they connect neurons together and transmit signals across
the neurons
Chemical and electrical synapses
the primary excitatory neurotransmitter in the brain
Glutamate
the principal inhibitory neurotransmitter in the brain
GABA
single amino acid residues released from presynaptic nerve terminals in response to an action potential and cross the synaptic cleft to bind with specific receptor on the postsynaptic membrane
glutamic acid, GABA, aspartic acid, and glycine
The nervous system is composed of billions of specialized cells called
neurons
the cells of chemical communication in the brain
Neurons
In its most basic form, a neuron has two ends:
an axon
and a dendrite
are chemical substances that act as the mediator for
the transmission of nerve impulses from one neuron to another neuron through
synapses.
Neurotransmitters
Neurotransmitters are stored in the axon (or presynaptic neuron) in little packages called ___
synaptic vesicles
The release of neurotransmitter is triggered by the arrival of ___
nerve impulse (or action potential)
are specialized junctions through which cells of the nervous system signal to one another and to
non-neuronal cells such as muscles or glands
Synapses
The process by which the information is communicated through synapse is called
synaptic transmission
The secreted neurotransmitters can act on receptors on the membrane of the postsynaptic neuron through a gap called ___
synaptic gap
a junction between neurons that allows different molecules and ions to pass freely between cells
gap junction
A gap junction is composed of ___
connexons
each connexon is composed of ___ connexin proteins
six
Synapses between axons and dendrites are called
axodendritic
Particularly powerful synapses made between axons of one neuron and cell body of another postsynaptic cell are called ___
axosomatic synapses
The three major categories of substances that act as neurotransmitters are:
Amino acids
Amines
Others: The one which do not fit in any of these categories (acetyl choline and
nitric oxide)
The neurotransmitters of this group are involved in fast synaptic transmission and are inhibitory and excitatory in action
Amino acids
are the modified amino acids
Amines
The neurotransmitters of this group involve in slow synaptic transmission and are inhibitory and excitatory in action
Amines
noradrenaline, adrenaline, dopamine, serotonin, and histamine are
Amines
glutamic acid, GABA, aspartic acid, and glycine are
Amino acids
the two amino acids are often are
found together at axon terminals
Aspartate
glutamate
The two amino acids functioning as excitatory neurotransmitter are
Aspartate
glutamate
acts as a brake to the excitatory neurotransmitters
GABA
Neurotransmitters can be classified as either
excitatory
inhibitory
__ neurotransmitters function to activate the receptors on the postsynaptic membrane and enhance the effects of action potential
Excitatory
The action potential is produced by an influx of ___ through voltage dependent calcium-selective ion channels
calcium ions
When the depolarization near the axon hillock reaches about ___ as a result of summation of EPSPs, a neuron will fire an action potential
−55 mv
is a summation of signals that brings the membrane closer to the threshold (depolarizing effect)
excitatory
postsynaptic potential (EPSP)
drives the membrane away from threshold by a hyperpolarizing effect.
inhibitory postsynaptic potential (IPSP)
a temporary increase in postsynaptic membrane potential within dendrites or cell bodies caused by the flow of sodium ions into the postsynaptic cell
excitatory postsynaptic potential (EPSP)
they hyperpolarize the postsynaptic membrane and produce IPSP
GABA and glycine
The most common inhibitory neurotransmitters in the nervous system are
γ-aminobutyric acid (GABA) and glycine
is used at the great majority of fast excitatory synapses in the brain and spinal cord
Glutamate
Glutamatergic neurons are particularly prominent in the ___
cerebral cortex.
EPSP-producing glutamate receptors (4)
- NMDA receptors (named for N-methyl-D-aspartate)
- AMPA receptors (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate)
- Kainate receptors
- Receptors which are activated by quisqualate
very important for controlling developmental synaptic plasticity and learning and memory function
NMDA receptor
The function of NMDA receptors is totally dependent upon ___
AMPA receptors
Kainate receptors can be activated by ___ and __
kainite and glutamate
the most ubiquitous inhibitory neurotransmitter in the brain
GABA
It was the first amino acid to be established as a neurotransmitter in vertebrate and invertebrate nervous systems
GABA
GABA exerts its effects via ___ and ___ receptors
ionotropic (GABAA)
metabotropic (GABAB)
GABA A receptors are ___ channels that in response to GABA binding increases chloride influx
into the neuron
chloride
The GABA B receptors are ___ channels that when activated by GABA leads to potassium efflux from the cell
potassium
the simplest of amino acids, consisting of an amino group and a carboxyl (acidic) group attached to a carbon atom.
Glycine
a potent neurotransmitter in the spinal cord and brain
Glycine
Glycine is a constituent of ___, an antioxidant tripeptide found in high concentrations in intestinal
epithelial cells.
glutathione
functions as an excitatory transmitter during embryonic development and is an essential coagonist at glutamatergic
synapses containing the NMDA subtype of glutamate receptors.
Glycine
____ converts the amino acid serine to glycine
Hydroxymethyl transferase
Glycine receptors are ligand-gated ___ that increase Cl− influx.
ion channels
Glycine molecules may be taken back into the presynaptic cell by two high affinity glycine transporters
Glyt-1 and Glyt-2
Glyt-1 is found primarily in __ cells, whereas Glty-2 is found primarily in ___ cells
glial
neuronal
is a glycine antagonist which can bind to the glycine receptor without opening the
chloride ion channel
Strychnine
is a strychnine-sensitive
glycoprotein which is composed of five subunit
GlyR
are nonessential amino acids that do not cross the
blood-brain barrier and, therefore, are synthesized from glucose and a variety of
other precursors
Glutamate and aspartate
The synthetic and metabolic enzymes for glutamate and aspartate
have been localized to the two main compartments of the brain
neurons and glial
cells
the most abundant excitatory neurotransmitter in the CNS
Aspartate
Unlike glycine, however, aspartate is an ___ neurotransmitter, which increases the likelihood of depolarization in the postsynaptic membrane
excitatory
