Synaptic Transmission Flashcards
Describe the different types of synapses – chemical vs electrical Develop understanding about the mode of release of NT and spontaneous postsynaptic potentials – quantal release of NT EPSPs, IPSPs, currents and NT responsible for initiating them Synaptic integration – summation and types of inhibition Electrical signalling types – gap junctions and ephaptic coupling
What is Synaptic Transmission?
How a nerve cell communicates with another?
What 2 groups can synapses be categorized into?
Electrical and chemical
How are electrical synapses set up?
Pre and post synaptic terminal has gap junctions between them, very close together; are connected by gap junction channels
How are chemical synapses set yp?
Pre and post synaptic terminal seperated by a cleft and chemical tansmitters are released where they bind with the post synaptic terminal - no connection
What is a gap-junction channel composed of
hemichannels (connexons)
Whaat are hemichannels composed of
6 identical subunits : connexins
What is an example of why electrical synapses are useful?
Speed : tail-flip response for goldfish is through electrical synapses to the motor units from the mauthner cell -> quick escape = alive goldfish
Who coined the term Synapse?
C.S. Sherrington
did research on reflexes
What is The monosynaptic reflex?
Simplest reflex arc involving a direct connection between a sensory neuron and a motor neuron in the spinal cord.
Example: knee-jerk reflex.
Who demonstrated chemical transmission?
Otto Loewi
AcH conveying messages to the vagus nerve in frog heart
What are the steps of chemical transmission?
- Synthesis and storage of neurotransmitter
- Conduction of action potential down the axon of a neuron
- Opening of voltage-gated Ca2+ channels
- Release of transmitter into the synaptic cleft
- Activation of postsynaptic receptors
- Breakdown/ reuptake of neurotransmitters
What is the difference between neurotransmitters and neuropeptides?
Neuropeptides produced in cell body (large, dense-core vesicles)
Small NTs produced in presynaptic terminal (small, clear vesicles)
What decides which are released (neurotransmitters and neuropeptides)?
Low frequency activity often release small neurotransmitters
High frequency releases neuropeptides
What are ‘quanta’?
Neurotransmitter is released in discrete packages termed ‘quanta’
What is the total post synaptic potential (PSP) made up of?
integral of number of quantal responses
