The Synapse

Question 1

What are the two types of synapses?

Answer 1

Electrical synapse

Chemical synapse

Question 2

What is an electrical synapse?

Answer 2

Very rate in adult neurons
Junction between the neurons is very small. Gap is spanned by proteins which are used to communicate between the neurons - ions move freely

Question 3

What is a chemical synapse?

Answer 3

Very common in adult neurons
Chemicals (neurotransmitters) are pleased from the presynaptic neuron to communicate with the post synaptic neurons. They travel through the synaptic cleft, the junction between the neurons is 20-50nM. NTs are released and post synaptic neuron hears it

Question 4

When does neuron communication happen?

Answer 4

At the synapse

Question 5

What are the types of neurons?

Answer 5

Pre synaptic - sends the signal, releases the NT

Post synaptic - receives the signal, lots of signalling machinary

Question 6

What are the 3 types of synapse locations?

Answer 6

Axodendritic - the axon goes on a dendrite and controls post synaptic neuron

Axosomatic - inhibitory connections, the axon goes on the soma

Axoaxonic - axon is on another axon and modulates the signal

Question 7

Where are the majority of synapses?

Answer 7

Axodentritic - the axon is attached to a dendrite

Question 8

What does activation of an excitatory synapse lead too?

Answer 8

A local and small depolarisation of the postsynaptic cell known as an EPSP

Question 9

What is decremental decay?

Answer 9

When an EPSP decays over the length of the dendrite

Question 10

What happens if the synapse is closer to the soma?

Answer 10

The greater its influence on the production of an action potential in an axon, the less decay

Question 11

What happens to all inputs?

Answer 11

They are summated at the soma (cell body) - if there is enough excitation, then an AP is generated at the axon hillock

Question 12

Why does synapse location matter?

Answer 12

Because the closer the synapse is to the soma, the greater the influence. the further away, the more decay there is

Question 13

What is an EPSP?

Answer 13

Excitatory postsynaptic potential

Question 14

What is the process at the chemical synapses?

Answer 14

1. The action potential travels down the axon
2. When it gets to the synapse, depolarisation open voltage gated calcium channels
3. Influx of calcium leads to neurotransmitter release
4. Neurotransmitter binds to and activates receptors on the dendrites of the postsynaptic cell
5. This leads to depolarisation or hyper polarisation of the postsynaptic cell
6. This spreads to the postsynaptic cell, where summation occurs
7. If there is enough depolarisation, then an action potential is generated at the axon hillock