Synapses Flashcards
What is the aim of synapses?
Transmit signal from one neuron to another
What are the two types of synapses?
- Electrical synapses
- Chemical synapses
What is a post-synaptic potential?
- EPSP (excitatory postsynaptic potential)
- IPSP (inhibitory postsynaptic potential)
What characterizes one-way transmission in synapses?
Rectifying
What characterizes two-way transmission in synapses?
Non-rectifying
What is the primary mechanism of electrical synapses?
Direct transfer of ions
What is the synaptic delay in chemical synapses?
0.5 - 2 ms
Who discovered ‘Vagusstoff’ and when?
Otto Loewi in 1921
What are SNARE proteins?
- Synaptobrevin
- SNAP-25
- Syntaxin
What triggers vesicular release in chemical synapses?
Rise in intracellular calcium concentrations
What is meant by ‘quantal release’?
Release of neurotransmitters in discrete packets (quanta)
How many quanta are typically released per action potential?
Up to 200 quanta
What does MEPP stand for?
Miniature End Plate Potential
What is the role of clathrin in vesicle recycling?
Forms a coated pit for vesicle retrieval
What toxin blocks P/Q-type voltage-gated calcium channels?
ω-agatoxin IVA
What is the LD50 of botulinum toxin in humans?
Around 2 ng/kg
What is the primary action of botulinum toxin?
Cleaves SNARE proteins to stop neurotransmitter release
What does α-bungarotoxin block?
Nicotinic acetylcholine receptors
What is the effect of physostigmine?
Inhibits acetylcholinesterase, increasing acetylcholine levels
Fill in the blank: The vesicle cycle is maintained by _______.
Clathrin
True or False: Chemical synapses have a faster transmission speed than electrical synapses.
False
What is a characteristic of ‘mini’s’ in neurotransmitter release?
Occur spontaneously, even in zero extracellular Ca2+
What is the effect of lowering extracellular Ca2+ on EPSP amplitude?
Decreases in a step-wise manner
What are the two types of release in quantal release?
- Spontaneous release
- Evoked release
