Lecture 3: What Happens at the Synapse?

Question 1

What is the basic structure of a synapse?

Answer 1

• Presynaptic membrane
• Synaptic cleft
• Postsynaptic membrane

Question 2

What is the presynaptic membrane?

Answer 2

Contains vesicles with neurotransmitters

Question 3

What is the synaptic cleft?

Answer 3

20-40nm gap that contains extra cellular fluid

Question 4

What is the postsynaptic membrane?

Answer 4

Contains specialised receptor proteins for neurotransmitters

Question 5

What is temporal summation?

Answer 5

Neuron release several NT over a specific time period

Question 6

What is spatial summation?

Answer 6

Many neurons are stimulated at once

Question 7

What is an EPSP?

Answer 7

Graded depolarization in the postsynaptic membrane in response to NT

Question 8

What is an IPSP?

Answer 8

Hyperpolarizing postsynaptic potential that decreases the chances of AP generated

Question 9

What is a graded potential?

Answer 9

Changes in membrane potential that vary according to size of stimulus

Question 10

What are the stages of transmitter release?

Answer 10

1. Action potential arrives at presynaptic axon terminal
2. The calcium channels open and the calcium flows in
3. Calcium causes vesicles to bind to presynaptic membrane and burst, releasing neurotransmitter into synaptic cleft
4. Neurotransmitter diffuses across the cleft, binding to receptors in postsynaptic membrane
   ISPs and EPSPs spread towards the axon hillock
5. Neurotransmitters separate from receptors

Question 11

What is exocytosis?

Answer 11

Vesicle membrane fuses with presynaptic membrane and causes NT to be released into synaptic cleft

Question 12

What are ionotropic receptors?

Answer 12

Ligand gated proteins that facilitate the transport of ions, open when bound to receptors

Question 13

What are metabotropic receptors?

Answer 13

NT binds onto the receptor that triggers cascade of events, slow long lasting effect