Lec 29 - Synaptic transmission

Question 1

List the components involved in synaptic transmission between neurons

Answer 1

Pre synaptic neuron -> axo-dendritic synapse -> post synaptic neuron

Question 2

What is an neuromuscular junction?

Answer 2

The point where the neuron meets the muscle fiber. aka the end plate

Question 3

What is the presynaptic terminal?

Answer 3

The part of the neuron that the neurotransmitters come from

Question 4

What is the neurotransmitter at the neuromuscular junction?

Answer 4

Acetylcholine (Ach)

Question 5

what is the mechanism used for the release of the transmitter from the neuron?

Answer 5

Exocytosis

Question 6

What is a synaptic cleft?

Answer 6

The location that neurotransmitters are released to go to

Question 7

What is special about the end plate potential?

Answer 7

It always triggers an action potential (is always suprathreshold)

Question 8

What is the ionic mechanism of end plate potentials and what is the name of the channel?

Answer 8

The opening of ion channels permeable to both Na+ and K+
these are called non selective cationic channels

Question 9

What are the two types of synapses in the CNS?

Answer 9

Excitory and inhibitory

Question 10

What is an excitory synapse

Answer 10

In the CNS
Depolarisation of the post-synaptic membrane called the Excitory postsynaptic potential (EPSP)

Question 11

What is an inhibitory synapse?

Answer 11

hyperpolarisation of the post-synaptic membrane, called the inhibitory postsynaptic potential (IPSP)

Question 12

Name the common neurotransmitters for EPSPs?

Answer 12

Acetylcholine and glutamic acid

Question 13

What are the ionic mechanisms or EPSPs?

Answer 13

Transient opening of channels permeable to Na+ and K+ and sometimes Ca2+
(allows cations into post-synaptic neuron)

Question 14

Name the common neurotransmitters for IPSPs?

Answer 14

Gamma-aminobutyric acid (GABA)
glycine

Question 15

What are the common ionic mechanisms for IPSPs?

Answer 15

Transient opening of K+ channels
(allows K+ into post-synaptic neuron)

Question 16

Name the two classifications of neurotransmitters

Answer 16

small molecule neurotransmitters
neuropeptides

Question 17

Name the features of small molecule neurotransmitters

Answer 17

• Fast action and direct on postsynaptic receptors
• Amino acids (GABA, glycine, glutamate)
• acetylcholine
• amines (seratonin (5-HT), noradrenaline, dopamine

Question 18

Name the features of neuropeptides

Answer 18

• larger, slower acting and tend to be by diffusion
• Have an indirect action (metabrotropic) on postsynaptic receptors or modulatory action on the effects of other neurotranmitters

Question 19

Name some common neuropeptides

Answer 19

Neuropeptide Y, substance P, kisspeptin, Enkephalin

Question 20

What are the factors effecting synaptic action/strength?

Answer 20

• type of neutrotransmitter/neuromodulator
• Type of neurotransmitter receptor/channel complex at the postsynaptic membrane
• The amount of neurotransmitter present in the postsynaptic membrane- synaptic plasticity

Question 21

What are the two types of synaptic plasticity?

Answer 21

Long term potentiation (LTP)
Long term depression (LTD)

Question 22

What are the three receptors glutamate can bind to and what are their qualities of synaptic response?

Answer 22

NMDA (slower synaptic response)
AMPA (fast synaptic response)
Kainate (response that is slow in amplitude, but slow to deactivate and acts over a long period of time)
(but keep in mind other things can bind to these receptors too)

Question 23

Describe the process of neurotransmitter inactivation

Answer 23

• diffusion away from the synapse
• Enzymatic degradation in the synaptic cleft
• Re-uptake of most of the amino acids and amines and re-cycling
• there is also involvement of specific neurotransmitter transporters in the pre-synaptic membrane (glutamate tranporters, dopamine tranporters or seratonin transporters)

Question 24

In order to depolarise the initial segment to threshold, the EPSPs need to be _______

Answer 24

Enhanced

Question 25

Will a neuron be specific to either excitory or inhibitory synapses?

Answer 25

No, all CNS neurons will do both

Question 26

Where does an individual synapse produce a postsynaptic potential and what is the potential value?

Answer 26

At the axon inital segment
~0.1mV