SYNAPTIC TRANSMISSION

Question 1

How does communication occur in the nervous system?

Answer 1

Electrical communication occurs along axons: the generation of an AP at the axon hillock then along the axon

Question 2

Where does chemical communication occur?

Answer 2

Chemical communication occurs at the synapses

Question 3

At synapses what happens?

Answer 3

At the synapse, communication involves the release of a chemical neurotransmitter, then the neurotransmitter is released by the presynaptic neuron.

Question 4

What do calcium ion channels do?

Answer 4

Voltage-gated calcium ion channels allow facilitated diffusion, Ca+ goes along the con. gradient and Ca+ go into cells, the increase of Ca+ con doesn’t last long.

Question 5

What is the importance of the short distance between the synapse and the channels?

Answer 5

The short distance between synapse and cleft to receptors allows the neurotransmitters to diffuse across to stimulate (FIG)

Question 6

How are the neurotransmitters released?

Answer 6

It is done by exocytosis, it is the mechanism of the transmitter release of neurons

Question 7

STEPS TO RELEASE OF NEUROTRANS.

Answer 7

1) The impulse comes down the axon
2) causes depolarisation, causing the Ca+ voltage gates to open
3) release of the transmitter by exocytosis (the effect of the postsynaptic neuron, causing an influx)
4) the neurotransmitter doesn’t stay, so it disperses quickly
5) EPSP: excitatory postsynaptic potential is depolarisation at the postsynaptic membrane (excitatory potential)
OR
IPSES: inhibitory postsynaptic potential if hyperpolarisation at the postsynaptic membrane

Question 8

NOTE

Answer 8

Most postsynaptic potentials decline before they reach axon hillock

Question 9

What is temporal summation?

Answer 9

where several EPSPs from the same synapse affect each other (it can reach the axon hillock AP)

Question 10

What is the spatial summation?

Answer 10

Where two or more EPSPs from different synapses occur (depol)

Question 11

Summary of Postsynpatic potential?

Answer 11

• small ones that are generated at the end of the axon an produces a change
• Excitatory (EPSP) or inhibitory (IPSP)
• graded
• local
• at the cell body/dendrites

Question 12

Summary Action potential

Answer 12

• depolarisation
• all or nothing
• excitatory postsynaptic potentials can add up and cause an AP
• generated at Axon hillock and travels along axon

Question 13

What are the different types of chemical synaptic transmission>

Answer 13

direct and indirect

Question 14

What happens in direct synaptic transmission

Answer 14

where the neurotransmitter opens ion channels on the postsynaptic membrane.

• action via-ligand gated ion channels
• leads to postsynaptic potential (graded)
• EPSPS (depolar)
• IPSPS (hyper)

Question 15

What happens in indirect synaptic transmission?

Answer 15

• neurotransmitters bind to a receptor on the postsynaptic membrane
• activates a signal transduction pathway
• involves a second messenger
• results in EPSPs/IPSPs depending on neurotransmitter and receptor type.

Question 16

EPSP and IPSP?

Answer 16

The EPSP facilitates the generation of an action potential on the postsynaptic membrane whereas the IPSP inhibit the generation of an action potential. The main difference between EPSP and IPSP is the effect of each type of electric charges on the postsynaptic membrane