ELM9: Synapses Flashcards
What are the characteristics of an electrical synapse?
Gap junction
Direct ion transfer
Non rectifying
Fast transmission
2 connexons of 6 connexins
Why don’t drosophila have the escape reflex?
Have innexins not connexins so gap junctions aren’t formed
What are some characteristics of chemical synapses?
Adaptable
Primary communications of neurons
Who was Otto Loewi?
Identified first neurotransmitter
Discovered Vagusstoff in 1921
How does the chemical synapse transmit a signal?
- Action potential opens calcium gated channels
- Causes neurotransmitter release
- Diffuse across and bind to receptor
How can enzymes be used to turn off the signal from an action potential?
Break down neurotransmitters in synaptic cleft
How can the uptake system be used to turn off the signal from an action potential?
Brings neurotransmitter back into neuron for reuse
What are some examples of SNARE proteins?
Synaptobrevin
SNAP-25
Syntaxin
How do SNARE proteins help with synaptic transmission?
- SNARE proteins bind to each other
- Bring vesicle with neurotransmitters closer to membrane
- Action potential increases calcium concentration
- Vesicle fuses with membrane and contents released into synapse
- Calcium sensed by vesicle protein synaptotagmin
What is evoked release?
Action potential and calcium entry triggers neurotransmitter release
What is spontaneous release?
No action potential or calcium entry but neurotransmitters still exist
What is meant by the quantal hypothesos?
Neurotransmitter release is quantal
Quantal content = EPP current / 1 quantum current
What is meant by 1 quantum current in the quantum hypothesis?
The amount of transmitter per vesicle
What are miniature postsynaptic potentials?
Happen spontaneously
Amplitudes that are multiples of a quantal unit
Due to release of quanta
What is the role of clathrin at the synapse?
Maintain constant vesicle size
Constant number of vesicles Constant size of terminal
