Synaptic transmission Lec06

Question 1

EPSPs increase the probability for an action potential to be generated because they let _____ into the cell body depolarizing the cell.

Answer 1

sodium

Question 2

IPSPs decrease the probability for AP by

Answer 2

letting K out or chlorine in

Question 3

direction of electrical synapses

Answer 3

bidirectional

Question 4

electrical synapses are connected via

Answer 4

gap junctions (made of connexins)

Question 5

what kind of pores do electrical synapses have? what do they let in

Answer 5

very large pores for unselective ion diffusion

Question 6

what triggers vesicle fusion?

Answer 6

influx of ca through voltage gated ca channels

Question 7

what happens if you have no Ca voltage gated channels

Answer 7

no NT release

Question 8

what happens if you ↓ external [Ca]

Answer 8

↓ # of vesicles = ↓ postsynaptic potential

Question 9

Ionotropic receptors - ligand-gated ion channels respond in ____

Answer 9

msec

Question 10

Metabotropic receptors - G-protein-linked receptors that respond in ___

Answer 10

sec/min (growth factor recpeotrs take even longer)

Question 11

how does inactivation of chemical nt take place

Answer 11

via reuptake, glial uptake, diffusion, or enzymatic breakdown

Question 12

what are the advantages of chemical synapses

Answer 12

directionality, amplification, plasticity, summation

Question 13

what is facilitation

Answer 13

short-term synaptic plasticity

Question 14

what does facilitation involve? what does it result in?

Answer 14

multiple action potentials in a short time (<50 msec) = ↑↑ in synaptic strength

Question 15

describe the 2nd epsp after facilitation

Answer 15

2nd EPSP larger than the 1st because Ca clearance is slower than Ca entry into cell

Question 16

how large are small molecule nt

Answer 16

50 nm diameter

Question 17

how are small molecule NT stored?

Answer 17

in clear vesicles

Question 18

some ___ are docked at active zones

Answer 18

small molecule nt

Question 19

docked small molecule nt are released by

Answer 19

local ca influx

Question 20

how are neuropeptides stored?

Answer 20

dense core vesicles

Question 21

what is required for neuropeptide release?

Answer 21

high frequency stimulation

Question 22

Vesicle release is quantal/discrete: each vesicle =

Answer 22

1 mini end plate potential

Question 23

how do miniend plate potentials cause depolarization?

Answer 23

Many MEPPs make up the endplate potential, EPP, causing depolarization

Question 24

how can you get larger mini end plate potentials?

Answer 24

more ach or more veiscles

Question 25

cable theory

Answer 25

neuron changes in synapse potential decrease with time and space

Question 26

\_\_\_ and ___ determine probability of an action potential due to leakage

Answer 26

Temporal and spatial summation

Question 27

EPSP & IPSP **_amplitude_** & **_direction_** depend on

Answer 27

ion permeability and membrane voltage

Question 28

NMDA is slower, Mg-blocked, but allows \_\_\_

Answer 28

Ca entry

Question 29

GABA\_\_ receptors are ligand-gated channels

Answer 29

A

Question 30

GABA A receptors make __ with CL- ions

Answer 30

fast ipsp

Question 31

GABA A receptors have ___ subunits

Answer 31

5

Question 32

what increases the GABA A channel open time

Answer 32

a barbituate + gaba (increases the channel open time)

Question 33

GABA __ receptor are g protein linked and slower

Answer 33

B

Question 34

how many synapses does each neuron integrate ifnormation from?

Answer 34

multiple

Question 35

what are the 4 criteria for chemical NTs?

Answer 35

1) **present in presynaptic terminal.** 2) **released in response to stimulation** – release must be Ca2+ dependent. 3) **specific receptors** for the neurotransmitter must be present on the postsynaptic cell. 4) **mechanism to inactivate neurotransmitter** must be present (reuptake, enzymatic breakdown).

Question 36

what type of flow occurs through gap junctions in electrical synapses

Answer 36

passive flow

Question 37

how common are electrical synapses?

Answer 37

they are present in cns but less common than electrical synapses

Question 38

brainstem neurons that regulate breathing are synchronized by

Answer 38

electrical synapses.

Question 39

chemical syanspes provide potentiation for

Answer 39

1. excitation and inhbiiton 2. plasticity and remodeling

Question 40

what drives Ca into the presynatpic membrane

Answer 40

concentration gradient (more ca outside) electrical gradient

Question 41

what does facilitation result from?

Answer 41

prolonged elevation of presynaptic Ca

Question 42

Synaptic facilitation is a rapid increase in \_\_\_

Answer 42

synaptic strength

Question 43

. Facilitation is not observed if \_\_

Answer 43

two APs arrive far apart in time

Question 44

how many chemical transmitters can a single neuron release?

Answer 44

many

Question 45

what is the range of time courses of chemical transmitters?

Answer 45

msec to days

Question 46

trnasport of neuropetide vesicles is dependent on \_\_\_

Answer 46

ATP

Question 47

what is the postsynaptic density

Answer 47

an electron dense area with many receptors in the postsynaptic target cell

Question 48

The MEPPs result from the discharge of the contents of

Answer 48

a single synaptic vesicle

Question 49

post synaptic potentials resutl from

Answer 49

conductance changes to

Question 50

synaptic potentials are passive events that become progressively smaller at

Answer 50

greater distances ro

Question 51

why dont dendrites transmit AP?

Answer 51

1. they do not contain many Na+ channels 2. their thresholds for excitation are too high.

Question 52

what does capable theory take into account

Answer 52

1. **_membrane capacitance_** 2. **_embrane resistance_** 3. **_longitudinal cytoplasmic resistance_** between different parts of the neuron

Question 53

glutamate binding to ampa and nmda exhibits distinct

Answer 53

1. kinetics 2. pharmacologic sensitivites 3. target cell effects

Question 54

interposition of a ____ in a neuronal circuit can prevent overactity in the cns

Answer 54

inhbiitior synapse