Synaptic Transmission (6) Flashcards
What are the criteria for a neurotransmitter?
1- Present in the presynaptic terminal
2- Preseased in response to stimulation in a Calcium dependent manner
3- Specific receptors for the neurotransmitter must be present on the postsynaptic cell
4- Mechanisms to inactivate neurotransmitter must be presnt
Which is faster: electrical synapse or chemical synapse?
Electrical synapse
Which type of synapse is bidirectional?
Electrical Synapse
Through what mechanism are electrical synapses transmitted?
Through gap junctions
In what type of cells are electrical synapses important for?
They are important for glial cells
What type of synapses are more common in the CNS?
Chemical synapses
What is the function of post synaptic terminals?
Convert electrical signals into chemical signals (in the form of neurotrasnmitters released from synaptic vesicles across the synapse)
Which type of synapse provides amplification?
Chemical synapses
Which type of synapses provide the potential for excitation and inhibition and integration?
Chemical synapses
Describe the Calcium gradient?
There is a steep calcium concentration gradient.
Ca in ««<Ca out
How does calcium enter the nerve terminal?
Through volt-gated calcium channels
What is facilitation?
Short term synaptic plasticity that results from prolonged elevation of presynatic calcium levels
When can facilitation occur?
When 2 or more Action Potentials invade the presynaptic terminal within a few milliseconds of each other
In facilitation, why is the second EPSP larger?
Because prolonged elevation of Calcium following synaptic activity. Therefore, more neurotransmitter is released in response to the subsequent action potential.
Can a single neuron release multiple neurotransmitters?
Yes
What are the different categories of neurotransmitters?
Small molecules and Neuropeptides
Where are small peptide (amino acid) neurotransmitters synthesized?
in the presynaptic terminals
Where are neuropeptide neurotransmitters synthesized?
synthesized in cell body and are transported to the terminal via fast axonal transport
How does stimulation frequency influence neurotransmitter release?
Stimulation frequency influences transmitter release from different populations of synaptic vesicles
What type of NTs does low frequency stimulation release?
It releases small molecule neurotransmitters
What type of NTs does high frequency stimulation release?
It releases both classes of neurotransmitter
What region of the postsynaptic cell does the NT bind to?
It binds to the post synaptic density
EPP is a sum of what?
EPP is a sum of MEP
True or False:
Neurotransmitter release is quantal
True
True or False:
Most dendrites transmit Action Potentials
False.
Most dendrites do not transmit APs because they do not contain many Na channels and the thresholds are too high
What does the term “leaky” describe?
Dendrites
How are action potentials produced?
Local passive events that sum to either depolarize (EPSP) or hyperpolarize (IPSP) the cell
How type of receptrs does glutamate bind to?
Both ionotropic and metabotropic receptors
What is the major exitatory transmitter in the brain?
Glutamate
What is the major inhibitory neurotransmitter in the brain?
GABA
What is the “fast” glutamate channel?
AMPA
What is the “slow” glutamate channel?
NMDA
