Synaptic Transmission

Question 1

What is synpatic transmission?

Answer 1

Synaptic transmission (neurotransmission)= how neurons talk to one another.

Question 2

What 2 ways can synaptic transmission occur?

Answer 2

1. Electrically

2. Chemically

Question 3

Electrical transmission

Answer 3

-Uses gap junction, which directly connect neurons. This allows for AP’s to be sent in both directions (multi-directional). The speed of contraction increases.

Question 4

Chemical transmission

Answer 4

Uses synpatic gaps. Thus, signals travel slower and unidirectional.

Question 5

How does chemical transmission occur

Answer 5

1. Neurons make NT, which are then stored in the axon terminal.
2. AP will trigger release of NT via an influx of calcium (a second messenger)
3. NTs bind to receptor
4. Change in membrane potential
5. NT is [reuptaked], [diffuses away] or [enzymatically inactivated]

Question 6

What guidelines must you follow to be a NT?

Answer 6

1. Must be made in a presynaptic neuron
2. Must be released in response to a pre-synaptic AP.
3. Must bind to a receptor on a post-synaptic neuron AND it must respond.
4. Signal has to be terminated by inactivating the NT.

Question 7

What 2 sources can NT be made from?

Answer 7

1. Food substrates (amino acids like glutamine, glycine or aspartate)
2. Soma

Question 8

The release of NT is dependent on what?

Answer 8

Calcium and the increase in AP.

Question 9

Quantile hypothesis

Answer 9

The quantile hypothesis says that a vesicle will release 5-10K neurotransmitters (NTs).

This ensures that a set amount of NT is released to initate a reasonse.

Question 10

How can we release more NT’s?

Answer 10

We need more AP.

Question 11

What causes EPSPs?

Answer 11

1. Influx of Na+

2. Efflux of K

Question 12

What causes IPSPs?

Answer 12

1. Efflux of K

2. Influx of - charges

Question 13

What is spatial summation

Answer 13

many presynaptic neurons firing onto 1 post-synaptic neuron at the same time

Question 14

Temporal summation

Answer 14

One presynaptic neuron is firing overtime, producing EPSPs that bring the neuron closer to an AP.

Question 15

2 types of ACh receptors

Answer 15

1. nAChR (ionotropic)

2. mACR (metabotropic)

Question 16

nAChR mechanism

Answer 16

When ACh binds, it increases these membranes permeability to Na and K+. This causes depolarization

Question 17

mAChR mechanism

Answer 17

is a GCPR. ACh binds, causing the alpha-GTP to be released from the by subunit.

The [by subunit] will then elicit the response.

Question 18

Electrical tranmissions allows neurons to communicate with one another using

Answer 18

Gap junction

Question 19

Chemical transmission allows neurons to communicate with one another using

Answer 19

Synaptic gaps

Signals are slower and unidirectional

Question 20

What is responsible for tetanus (sustained contraction)?

Answer 20

Ca2+

Because the release of the NT will be dependent on Ca2+ and the AP.

Question 21

which muscles have nicotenic cholinergic receptors?

Answer 21

skeletal muscles

Question 22

which muscles have muscarinic receptors?

Answer 22

ANS

Question 23

If VGCa2+ are blocked, what MOA of medication can we give to counteract?

Answer 23

A drug that will activate synaptic vesicles to dock and fuse vesicles that have the NT.

Question 24

Ca2+ acts as what?

Answer 24

a second messenger

Question 25

Where is Ca2+ concentration greatest? inside or outside of the cell

Answer 25

Outside

Question 26

What happens if we have a greater concentration of Ca2+?

Answer 26

More NT is released!

Question 27

What is the threshold potential?

Answer 27

-55mV.

Question 28

What is hyperpolarization?

Answer 28

A change in the neuron that causes it to have a more - charge inside the cell

Question 29

Does hyperpolarization inhibit APs from occuring?

Answer 29

Yasss.