03 | Synaptic Transmission

Question 1

NMJ always use ___ NT and it is always ___. The receptor is always ___. The post-synaptic potential is called ___.

Answer 1

1. ACh
2. Excitatory
3. nAChR
4. End plate potential

Question 2

Define: EEP

Answer 2

Depolarization of skeletal muscle caused by NT binding at NMJ

Question 3

Schwann cells are support cells for the ___

Answer 3

PNS

Question 4

What is a postsynaptic feature unique to NMJ?

Answer 4

Postjunctional folds (increase SA)

Question 5

Distance between adjacent cells (value)

Answer 5

20 nm

Question 6

Distance of synaptic cleft

Answer 6

20-45 nm

Question 7

Ion that is prevalent at excitatory synapses

Answer 7

Na

Question 8

Ion that is prevalent at inhibitory synapses

Answer 8

Cl

Question 9

___ removes Cl from solution and inside cell

Answer 9

Isethionate

Question 10

Which way does the ion flow at its reversal potential?

Answer 10

No flow because conc. gradient is balanced with electrical gradient

Question 11

What is 1 difference between EPP and EPSP/IPSP?

Answer 11

EPP is degenerative (decrease with increasing distance from end plate)

Question 12

What kind of synapse does presynaptic inhibition occur at?

Answer 12

Axoaxonic

Question 13

Presynaptic inhibition is mediated by __ (NT) and __ (ion)

Answer 13

GABA, Cl

Question 14

What kind of synapse does postsynaptic inhibition occur at?

Answer 14

axosomatic or axodendritic

Question 15

Timing of EPSP and IPSP

Answer 15

If IPSP arrives before EPSP, excitation can’t happen. However, if IPSP arrives after EPSP, it will not stop the excitatory response.

Question 16

Direct synapses use ___ receptors, while indirect synapses use ___ receptors.

Answer 16

1. ionotropic

2. metabotropic

Question 17

Define: autoinhibition

Answer 17

NT binds to metabotropic receptors on presynaptic membrane in order to feedback and stop NT release

Question 18

List 3 examples of autoreceptors

Answer 18

1. GABA(B)
2. D2
3. α2-adrenergic

Question 19

Gs pathway

Answer 19

↑ AC ⇒ ↑ cAMP ⇒ ↑ PKA

Question 20

Gq pathway

Answer 20

↑ PLC ⇒ IP3 ⇒ DAG ⇒ PKC + increase [Ca]i from intracellular stores (ER)

Question 21

Gi pathway

Answer 21

↓ AC ⇒ ↓ cAMP ⇒ ↑ K channel opening ⇒ hyperpolarization

Question 22

Go pathway

Answer 22

↓ Ca channel opening → ↓ NT release

Question 23

G proteins are classified according to…

Answer 23

structure and target of α subunit

Question 24

Effect of GPCR pathways depend on…

Answer 24

1. Receptor
2. G protein
3. Effectors
4. Arrangement of 1-3 (e.g. multi-protein complexes)
5. NT

Question 25

Where is the G protein binding domain on GPCR?

Answer 25

TM III to VII

Question 26

How does GPCR work over short distances?

Answer 26

1) Ligand binds to receptor 2) GDP → GTP 3) G protein (with α, β, γ subunits) dissociates 4) β and γ subunit goes to ion channel and opens/close it (direct interaction)

Question 27

Effect of ECBs

Answer 27

overall inhibition of CNS (stop pain)

Question 28

Release of ECB

Answer 28

Produced in postsynaptic cell and released | - DOES NOT INVOLVE VESICLES

Question 29

What does 2-AG bind?

Answer 29

CB1 receptor on presynaptic membrane

Question 30

2-AG uses ___ inhibition

Answer 30

retrograde

Question 31

Define: volume transmission

Answer 31

Signalling to neighbour neurons

Question 32

What is volumen transmission called elsewhere in the body?

Answer 32

paracrine signalling

Question 33

What molecules are used for volume transmission?

Answer 33

NO, CO

Question 34

2 ways to increase [Ca]

Answer 34

1. Ionotropic-Rs act as Ca ion channels | 2. mRs act open intracellular Ca stores

Question 35

How many Ca does CaM bind?

Answer 35

4

Question 36

Effects of Ca-CaM complex

Answer 36

1. Open Ca-CaM channel 2. Activate CaM kinase 3. Activate NO synthase

Question 37

1 neuron can be connected with up to ___ neurons via electrical synapse

Answer 37

10

Question 38

electrical synapses are joined together by ___

Answer 38

connexins

Question 39

What is connexin-36?

Answer 39

6 TM connexons that form a pathway for current

Question 40

Is chemical or electrical synapses more reliable? Why?

Answer 40

electrical, because it can't be blocked by neurotoxins