Chemical Synapses

Question 1

What are the four types of synapses?

Answer 1

• Axodendritic
• Axosomatic
• Axoaxonic
• Dendrodendritic

Question 2

How big are the gaps of synapses?

Answer 2

20-50nm

Question 3

Can synapses grow and shrink?

Answer 3

Yes

Question 4

Transmission

Answer 4

1. Synthesis
2. Storage
3. Release
4. Post-synaptic effects
5. Inactivation

Question 5

Synthesis

Answer 5

By ribosomes in soma, packaged by Golgi and transported to terminal down axon. Each, amines and amino acid neurotransmitters are synthesised and packaged at the synaptic terminal

Question 6

Storage

Answer 6

Some neurotransmitter vesicles are ‘docked’ at the membrane before AP –> rapid release

Question 7

Release

Answer 7

Arrival of AP opens voltage-gated Ca2+ channels –> triggers exocytosis by Ca2+ influx. Synaptic cleft has small volume so [neurotransmitter] can reach mM range. Vesicles contain 35-50nM
Quantal release- NT released in vesicles called quanta - min.size

Question 8

What is quantal release?

Answer 8

Neurotransmitters are released in vesicles called quanta

Question 9

What are the vesicles that neurotransmitters are released in called?

Answer 9

Quanta

Question 10

What is special about a quanta?

Answer 10

Generates the smallest stimulation that one neurones can send to another

Question 11

Post-synaptic effects

Answer 11

Two main types of receptor: ionotropic and metabotropic

Question 12

Inactivation

Answer 12

• Broken down and reuptake into presynaptic terminal

- Taken up by astrocytes