Communication between neurons

Question 1

How many types of synapse are there?

Answer 1

3

Question 2

What is an axodendritic synapse?

Answer 2

Axon - Dendrite

A gap between an axon and a dendrite.

Question 3

What is an axosomatic synapse?

Answer 3

Axon - Soma

A gap between an axon and soma (cell body).

Question 4

What is an axoaxonic synapse?

Answer 4

Axon - Axon

A gap between two axons.

Question 5

What are EPSPs?

Answer 5

Excitatory post-synaptic potentials.

Question 6

What are IPSPs?

Answer 6

Inhibitory post-synaptic potentials.

Question 7

Does hyperpolarisation increase or decrease the chance of the firing of an action potential?

Answer 7

Hyperpolarisation means that the axon membrane is more negative, further away from -60mv and so is less likely to fire/more stable.

Decreases chance.

Question 8

Does hypopolarisation increase or decrease the chance of an action potential being fired?

Answer 8

Hypopolarisation means that the axon membrane is more positive, closer to-60mv and so is more likely to fire/less stable chance.

Increase chance

Question 9

What is a ligand?

Answer 9

A chemical that binds to a receptor (and the receptors binding site)

Question 10

What does affinity mean?

Answer 10

The extent to which a ligand can bind to a receptor.

Question 11

What is the evidence to back up the limitations of the lock and key metaphor?

Answer 11

• 5-HT can bind to 30 different receptors

- Dopamine and Noradrenalin can bind to the same receptors because they are similar in structure.

Question 12

What is the limitation of the lock and key metaphor?

Answer 12

Too specific.

Question 13

Describe the release of a transmitter from the moment that an action potential travels down an axon.

Answer 13

• Action potential opens voltage gated calcium channels.
• Calcium ions flood in and catalyse the vesicles containing transmitters to move along the axon to the terminal button.
• Vesicles bind to the pre-synaptic membrane, rupturing and releasing NT into the synaptic cleft.

Question 14

What is the difference between an ionotropic and metabotropic receptor?

Answer 14

The binding of a ligand to an ionotropic receptor causes a change in the 3D structure of the ‘gate’, allowing ions to flow through it. However, the binding of a ligand to a metabotropic receptor causes a G Protein to be activated, causing a second messenger to change the shape of a gate at a separate location in the axon membrane.

Question 15

What are the two ways that synaptic transmission can be terminated?

Answer 15

• Reuptake

- Enzymatic deactivation

Question 16

What is reuptake?

Answer 16

The removal of neurotransmitter from post-synaptic receptors and their return to the pre-synaptic vesicles.

Question 17

What is enzymatic deactivation?

Answer 17

The breaking down of neurotransmitter by enzymes.

Question 18

What is the more common method of terminating synaptic transmission?

Answer 18

Re-uptake - all but one enzyme works this way.