LECTURE 4 Flashcards
(34 cards)
How does the presynaptic membrane deliver information?
neurotransmitters
How does the postsynaptic membrane receive information?
receptors for neurotransmitters
What is a synapse?
is the primary location of neural communication with another cell
What is chemical synaptic transmission?
Release of a chemical at a synapse whereby by one cell influences another
What are the steps to create a synaptic potential?
Action potential arrives at the presynaptic terminal
Membrane of the presynaptic terminal depolarizes, opening Ca2+ channels
Influx of Ca2+ into the neuron terminal, combined with the liberation of Ca2+ from intracellular stores, triggers the movement of synaptic vesicles toward a release site in the membrane
Synaptic vesicles fuse with the membrane and release neurotransmitter into the cleft
Neurotransmitter diffuses across the synaptic cleft
Neurotransmitter contacts a receptor on the postsynaptic membrane and binds to that receptor
Binding causes receptor to change shape
What does altered configuration of the receptor do?
Opens an ion channel associated with the membrane receptor (Ligand-gated channels)
Activates intracellular messengers associated with the membrane receptor
When does presynaptic inhibition or facilitation occur?
if synapse is axoaxonic
what is local depolarization?
excitatory postsynaptic potential (EPSP)
what is local hyperpolarization?
inhibitory postsynaptic potential (IPSP)
In IPSP what channels open and what occurs?
cl and k channels open, hyperpolarization occurs
in EPSP what channels open and what occurs?
ca and na channels open, depolarization occurs
What is presynaptic facilitation?
occurs when neurotransmitter binding causes local depolarization of the postsynaptic axon terminal resulting in increased release of neurotransmitter
What is presynaptic inhibition?
occurs when neurotransmitter binding causes hyperpolarization of the postsynaptic axon terminal resulting in decreased release of neurotransmitter
What are three ways to remove neurotransmitters from the synaptic cleft?
neurotransmitter transporters, enzymatic degradation, uptake by glial cells
What is spatial summation?
many different synapses must produce EPSPs simultaneously at different locations in the membrane of the postsynaptic cell.
What is temporal summation?
summation of EPSPs in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times in rapid succession.
where are neuromodulators released and what do they adjust?
released into extracellular fluid and adjust activity of many neutrons.
where are neurotransmitters released and what effect do they have?
are released into synaptic cleft, Act directly on postsynaptic ion channels or indirectly activate proteins inside the postsynaptic neuron
what is ionotropic?
neurotransmitters that activate ion channels directly, fast
what is metabotropic?
neurotransmitters that activate proteins inside the postsynaptic neuron indirectly, slow
What is substance P?
common neuropeptide, stimulates nerve endings at site of injury and then in the CNS.
What three mechanisms are used to transduce signals in postsynaptic receptors?
Directly open ion channels, indirectly open ion channels, indirectly activate a cascade of intracellular events.
What does the release of G protein do?
binds to specific ion channels resulting in their opening
In the second-messenger system activation of receptors will?
Activate genes, resulting in changes in quantities of neurotransmitters and receptors
Open ion channels
Regulate intracellular Ca2+ concentrations (cell metabolism)
