Synaptic Transmission

Question 1

What are the two types of neurotransmission?

Answer 1

chemical speed and electrical speed

Question 2

What are the 3 factors in electrical speed of neurotransmission and an example?

Answer 2

1. speed is fast
2. gap junctions connect pre and post synaptic neuron directly
3. Multidirectional signaling (both ways)
   Ex: signaling in the heart

Question 3

What are the 3 factors in chemical speed of neurotrasmission and an example?

Answer 3

1. slow speed
2. synaptic gap between pre and post synaptic neuron
3. unidirectional signaling
   Ex: autonomic nervous system (ANS)

Question 4

What are the first two steps of chemical synapse?

Answer 4

1. the neuron synthesizes neurotrasmitters (NTs) in pre-synaptic neuron
2. Neurotransmitters stored in axon terminal of neuron

Question 5

What are the next two steps after the neurotransmitters are stored in the axon of the pre-synaptic terminal?

Answer 5

3. An action potential will trigger the release of NTs, opening Ca2+ channels, net influx of Ca into pre-synaptic
4. Influx of calcium makes NTs fuse with pre-syn wall, and release NTs (inside vesicle) to bind to the receptor in post-synaptic neuron

Question 6

What are the final steps after the NTs bind to the receptor in the post-synaptic neuron?

Answer 6

5. There will be a post-synaptic response, changing the membrane potential
6. The NTs have to be taken up by the pre-synaptic neuron, diffused away, or enzymatically inactivated to inhibit the response

Question 7

What is the first criteria of being a neurotransmitter?

Answer 7

1. needs to be synthesized in the pre-synaptic neuron, made from 1-food substrate AA (Glu,Gly,Asp) 2-soma of neurons

Question 8

What is the second criteria of being a neurotransmitter?

Answer 8

2. Released in response to pre-synaptic AP
   - Ca 2+ dependent
   - Quantal Hypothesis
   - NT released inc= [inc Ca] + [inc AP]

Question 9

What is the quantal hypothesis?

Answer 9

Each time a synaptic vessicle is released, 5000-10000 NTs are released

Question 10

What is the third criteria of being a neurotransmitter?

Answer 10

3. post-synaptic receptors receive signal and respond ***need to cause response

Question 11

What is the fourth criteria of being a neurotransmitter?

Answer 11

4. NTs must be inactivated (drugs can do this)

Question 12

What are the four types of NTs and some examples?

Answer 12

1. choline esters: mAchR, nAchR
2. Bioenic Amines: Dopamine, Nor/Epinephrine, Seratonin
3. Amino Acids: Glutamate, Glycine, Gaba
4. Neuropeptides: ACTH, Glucagon, Endorphins

Question 13

What is EPSP (excitatory post-synaptic potential)?

Answer 13

Gets cell closer to threshold by either have K+ move out or Na+ in… a net positive (+) gain

Question 14

What is IPSP (inhibitory post-synaptic potential)?

Answer 14

Gets cell further away from threshold by moving K+ out or moving Cl- into cell… a net negative (-) gain

Question 15

What is spatial summation and how does it work?

Answer 15

EPSP only, many pre-synaptic neurons, all signals at same time (will see mound before AP fires) EX: N1 N2 N3 all send signal to presynaptic at one

Question 16

What is temproal summation and how does it work?

Answer 16

EPSP only, one pre-synaptic neuron, signaling is one at a time- over time,. EX: N1 N1 N1, signals over time making steps up to before the AP fires

Question 17

What are the two types of Acetylcholine receptors, and what type of receptors are they (different)?

Answer 17

Nicotinic Acetylcholine Receptor (nAchR): Ionotropic receptor (IONS)

Muscarinic Acetylcholine Receptor (mAchR): metabotropic receptor (GPCR)

Question 18

What are the steps in making a response in nAchR (4) and an example of ‘body part’ that uses it?

Answer 18

1. Acetylcholine binds to the nAchR
2. Increase in Na+, K+ permeability (opens channels)
3. Membrane Depolarizes
4. AP Excitation
   EX: Skeletal Muscle Contraction

Question 19

What are the steps in making a response in mAchR (3) and an example of a ‘body part’ that uses it?

Answer 19

1. Acetylcholine binds mAchR (GPCR)
2. GPCR releases Alpha-GTP subunit from Beta/Gamma (BY SU)
3. BY subunit elicits a variety of responses
   EX: ANS:Parasympathetic Nervous System (rest/digest)

Question 20

What happens when a drug/something blocks all nAchRs?

Answer 20

There will be no muscle contractions, which can lead to droopy muscles/no muscle spasms