Neurochemistry Flashcards
(63 cards)
action potential reaches the pre-synaptic terminal
voltage-gated Ca2+ channels open
Ca2+ enters terminal
Ca2+ causes synaptic vesicles to fuse with the presynaptic membrane
release neurotransmitter into the synaptic cleft=exocytosis
steps of exocytosis
vesicles
SNARE proteins
voltage-gated Ca2+ channels open
Ca2+ sensor
vesicles
packets of neurotransmitters
SNARE proteins
v-SNARES and t-SNARES
docked at presynaptic membrane, waiting to fuse
Ca2+ sensor
synaptotagmin
fusion and neurotransmitter release
If someone is exposed to a toxin that changes neurotransmitter release at muscles, they may experience ______
A. Muscle weakness or paralysis
B. Muscle tightening or spasms
C. Death
D. All of the above
neurotransmitters
basis of communication between neurons
many different chemicals act as neurotransmitters in brain: glutamate, GABA, dopamine, serotonin, norepinephrine, acetylcholine
each neuron uses one (or maybe two or three!) neurotransmitters; different neurons use different neurotransmitters
each neurotransmitter can trigger a different effect on the post-synaptic cell
neurotransmitter production
neurons must synthesize their neurotransmitter and move it to vesicles
a specific enzyme (protein) is involved in producing each neurotransmitter
often, that enzyme converts an amino acid we derive from our diet into a neurotransmitter
neurotransmitters cross the synaptic cleft
neurotransmitters diffuse across until they reach the post-synaptic membrane
extra neurotransmitter is degraded by enzymes, or taken up by presynaptic terminals or astrocytes
post-synaptic density
dendrites/spines have post-synaptic densities with receptors
neurotransmitters bind to receptors on post-synaptic membrane
ionotropic receptors
ligand-gated ion channels
chemically activated by neurotransmitter binding
coupled to G-proteins, which in turn couple to other enzymes/channels (GPCR)
slower biochemical changes within the cell (second messenger systems)
metabotropic receptors
receptor activates G-protein (so also called G-protein coupled receptor)
agonist
an naturally occurring molecule (ligand) or drug can bind to the receptor and open in
unbound receptor
receptors are normally closed
antagonists
some substances bind to receptors but do not activate them. instead, they simply block agonists from binding to the receptors
Ligand-gated ion channels are activated by ____
A. Ions
B. Neurotransmitters
C. Voltage
D. Temperature
B. neurotransmitters
neurotransmitters/receptors open post-synaptic ion channels
cation (Na+, K+, Ca2+) or anion (Cl-) channels
post-synaptic potential (PSP)
electrically charged ions cross membrane
excitatory or inhibitory PSP
PSP can spread through dendrite to cell body and axon hillock
excitatory post-synaptic potential (EPSP)
cations flow in-> depolarize the neuron
inhibitory post-synaptic potential (IPSP)
anions flow in-> hyperpolarize the neuron
Whether a PSP is excitatory or inhibitory depends on the
____
A. Type of neurotransmitter released
B. Size and shape of the action potential
C. Type of voltage-gated channel that opens
A. type of neurotransmitter released
C. type of voltage-gated channel that opens
cations enter cell
membrane potential becomes less negative
depolarizes (less polarized)
excitatory post-synaptic potential
anions enter cell (or cations exit)
membrane potential becomes more negative
hyperpolarizes (more polarized)
inhibitory post-synaptic potential
summation and integration
dendrites receive contacts from many neurons
individual EPSP/IPSP is very small and graded
