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Flashcards in Synaptic Transmission Deck (21)
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1
Q

What are the differences between electrical and chemical synaptic transmission?

A
  1. Speed; electrical is fast while chemical is slow
  2. Electrical neurotransmissions uses gap junctions while chemical has a synaptic cleft (gap)
  3. The direction of neurotransmission: electrical is multidirectional and chemical is unidirectional
2
Q

What is the first step of a chemical synapse?

A

Neuron is going to synthesize neurotransmitters

3
Q

What is the second step of a chemical synapse?

A

Neurotransmitters stored in axon terminal

4
Q

What is the third step in a chemical synapse?

A

Action potential will cause the release of neurotransmitters into the synaptic cleft (fusion of vesicle with membrane)

(Action potential triggers a calcium channel to open which causes influx of calcium (going down its concentration gradient), which will cause the release of neurotransmitters due to the new ion imbalance)

5
Q

What is the fourth step of chemical synapse?

A

Neurotransmitters travel to bind to receptor in post-synaptic

6
Q

What is the fifth step of the chemical synapse?

A

Post synaptic response = change in membrane potential

7
Q

What is the last step of a chemical synapse?

A

Neurotransmitters will either be taken up by the presynaptic cell, or diffuse into blood stream or be enzymatically inactivated

8
Q

What are the two precursors for synthesis of neurotransmitters in eapresynaptic neurons?

A

Amino acids (glutamine, glycine and aspartate) and can be made in soma of neurons

9
Q

What is the quantal hypothesis?

A

Each time a synaptic vesicle is released, about 5000-10000 molecules of neurotransmitter is released within that synaptic vesicle to be sure that you have an action potential.

10
Q

What two things is neurotransmitter release dependent on?

A

Neurotransmitter release is equal to the increase in calcium release plus the increase in action potential

11
Q

What are the four criteria of neurotransmitters?

A
  1. Synthesis in pre-synaptic neuron
  2. Release in response to pre-synaptic action potential (calcium dependent, quantal hypothesis, NT release)
  3. Post synaptic receptors receive signal and respond
  4. NTs must somehow be inactivated
12
Q

What are the different classifications of neurotransmitters?

A
  1. Choline esters (mAChR will bind to mAChR or nAChR)
  2. Biogenic amines (dopamine, epinephrine, norepinephrine and serotonin)
  3. Amino acids (glutamate, glycine, GABA)
  4. Neuropeptides (ACTH, glucagon, endorphins)
13
Q

What are the three post synaptic responses?

A

Action potential (all or none)

EPSP

IPSP

14
Q

What’s an EPSP? What moves in and out of the cell?

A

Depolarizations, which will get the cell closer threshold in order to action potential

Potassium moves out and sodium moves in (net gain positive charge)

15
Q

What’s an IPSP? What moves in and out of the cell?

A

Repolarizations, which will get the cell farther away from the threshold and action potential

Potassium moves out of the cell or a negative charge (chloride) will move into the cell (net negative gain)

16
Q

What is summation?

A

The addition of EPSPs and IPSPs

17
Q

What is spatial summation?

A

EPSP only; there are many pre-synaptic neurons firing onto one post-synaptic neuron, and it happens all at the same time.

18
Q

What is temporal summation?

A

EPSP only; theres is only one presynaptic neuron firing at a postsynaptic neuron over a period of time

19
Q

What are the acetylcholine receptors?

A

Nicotine AChR and muscarinic AChR

20
Q

What is the nicotinic AChR?

A

Ionotropic receptor (involves ions)

Acetylecholine binds the receptor and causes an increase in sodium and potassium permeability across the membrane; this change will cause membrane depolarization, which will then cause an action potential, and could cause skeletal muscle contraction for example

21
Q

What is the muscarinic AChR?

A

A metabotropic receptor (GCPR)

Acetylcholine binds to this receptor and causes part of the protein to release alpha-GTP subunit from the beta/gamma subunit, which will elicit a variety of responses and thats how the muscarinic receptor will signal (for example, autonomic nervous system, parasympathetic nervous system responses)