Dr. Karius' Synapse lecture

Question 1

Cell to Cell communication achieved by

Answer 1

Gap junctions

Question 2

Gap Junctions are made from

Answer 2

connexons

Question 3

Where might you find connexons?

Answer 3

in the heart because it creates rapid synchronicity

Question 4

Endocrine means the chemical messengers are

Answer 4

released into the blood

Question 5

Paracrine means the chemical messengers are

Answer 5

released via diffusion through Extracellular fluid (ECF) to neighboring cell

Question 6

Autocrine means the chemical messengers are

Answer 6

released nito ECF, and the chemical binds to receptos on the cell that released it.

Question 7

Which forms of chemical transmission uses the ECF as the route of transmission?

Answer 7

autocrine and paracrine

Question 8

Membrane specificity: receptors INSIDE the cell will be utilized by chemical messengers sent via _______

Answer 8

endocrine

Question 9

Neurotransmission may be classified as a specialized form of

Answer 9

paracrine communication

Question 10

Synaptic Cleft

Answer 10

1) is an actual Gap
2) has actual ECF in between the pre-and post sides
3) anatomically isolated

Question 11

Post-synaptic characteristics

Answer 11

1) densities = NT receptors
2) electron rich
3) contains receptors for neurotransmitter
4) Extensive surface area

Question 12

Pre-synaptic characteristics

Answer 12

1) mitochondria
2) Vesicles for storage
3) increased surfaced area

Question 13

Definition of neurotransmitter

Answer 13

a chemical mediator released from one neuron that acts on another neuron/excitable tissue at a synapse

Question 14

Cholinergic =

Answer 14

acetycholine

Question 15

Adrenergic =

Answer 15

dopamine 
norepinephrine 
epinephrine 
serotonin 
histamine

Question 16

Excitatory amino acids =

Answer 16

glutamate/aspartate

Question 17

Inhibitory amino acids =

Answer 17

glycine (spinal cord, brainstem)

GABA, CNS

Question 18

Order of events leading up to NT release

Answer 18

1) synthesis in soma or axon
2) transport to pre-synaptic terminal
3) packaging in vesicles
4) congregation of vesicles in “active zone” (docking and priming)

Question 19

NT release

Answer 19

: Axonal AP (Na influx, propagation) –> Presynaptic terminal influx of Ca through voltage gated Ca channels, depolarization opens channels

Question 20

What does Calcium do for the NT release between a pre and post synaptic terminal junction?

Answer 20

Calcium binds to a protein complex that draws the pre and post synaptic membrane terminals (between two axons) together to form a pore so NT can diffuse across

Question 21

Pre synaptic events (8)

Answer 21

1) depolarization of pre-syn terminal
2) opening of voltage gated calcium channels
3) influx of calcium into terminal
4) binding of calcium to appropriate proteins
5) conformational change in proteins brings docked vesicles to membrane
6) fusion of vesicular membrane with cell membrane
7) creation of fusion “pore”
8) diffusion of neurotransmitter into synaptic through/cleft

Question 22

What proteins make up the “protein” complex between terminals?

Answer 22

VAMPS/SNAPs

Question 23

Methods of ACh removal: the most basic is

Answer 23

diffusion, but limited by anatomy of synapse, can still have affects

Question 24

Least favored form of ACh removal

Answer 24

diffusion

Question 25

Method of ACh removal method 2

Answer 25

degradation or binding to proteins: only works for a few neurotransmitters

Question 26

Method of NT removal 3

Answer 26

Enzymatic destruction of ACh by AChE in synaptic cleft

Question 27

Method of NT removal 4

Answer 27

re-uptake (epinephrine): transporter protein will take NT back into presynaptic terminal

Question 28

mechanisms by which a nueurotransmitter's action is limited (3)

Answer 28

``` Enzymatic degradation (ACh) Natural degradation (NO) Re-uptake (Epinephrine/norepinephrine) ```

Question 29

How many ACh are needed to activated a voltage gated ion channel?

Answer 29

2

Question 30

What happens if the ACh opens a sodium or calcium channel (EAA) ?

Answer 30

Na/Ca enters the dendrite and causes depolarization to initiate an excitatory POST SYNAPTIC POTENTIAL (EPSP)

Question 31

EPSP

Answer 31

excitatory post synaptic potential produced by Na or Ca on a dendrite Local, graded, die away w/distance and time (~5 mV depolarization)

Question 32

Some of the dendrite does not have

Answer 32

voltage gated ion channels does have ligand gated ion channels no way to make an action potential

Question 33

If the soma does not have voltage gated ion channels, what does the axon hillock possess at its INITIAL SEGMENT

Answer 33

NO ligand gated channels voltage gated channels AP generation here

Question 34

Chloride channels

Answer 34

glycine and GABA cause HYPERPOLARIZATION initiate an inhibitory post-synaptic potential

Question 35

Glycine and GABA

Answer 35

NT's that act to allow Cl- into SOMA of the neuron causing an inhibitory post-synaptic potentials

Question 36

What's the spacial difference between Na/Ca channels and Cl- channels?

Answer 36

the Na/Ca are on the dendrites further from the cell body, the Cl- channels are closer to the body of the neuron

Question 37

IPSPs and EPSPs can

Answer 37

add together (summation)

Question 38

Two kinds of summation

Answer 38

Temporal and Spatial

Question 39

Temporal summation

Answer 39

multiple APs within a sec/msec (these would occur on the dendrite, not the cell body)

Question 40

Spatial summation

Answer 40

multiple synapses (+ or -) acting simultaneously synapses on both dendrites and soma

Question 41

SS: What will happen if both signals are positive?

Answer 41

little hump up + big hump up

Question 42

SS: What will happen if one signal is positive and one is negative

Answer 42

little hump down + big hump down

Question 43

SS: What will happen if one signal is positive and one is negative?

Answer 43

one round hump up and one slope down

Question 44

Ligand: GABA receptor, channel type, response type

Answer 44

ligand gated Chlorine channel IPSP

Question 45

Ligand: Glycine receptor, channel type, response type

Answer 45

ligand gated chlorine channel IPSP

Question 46

Ligand: NMDA (amino acid) receptor, channel type, response type

Answer 46

ligand gated Ca channel EPSP

Question 47

Ligand: amino acids receptor, channel type, response type

Answer 47

ligand gated Ca channel EPSP

Question 48

Ligand: ACh receptor, channel type, response type

Answer 48

Ligand gated Na channel EPSP

Question 49

``` Ligand: EAA Response: Ions Electrical response Effect on excitability ```

Answer 49

EPSP Na/Ca Depolarization Increased (more action potentials)

Question 50

``` Ligand: ACh Response: Ions Electrical response Effect on excitability ```

Answer 50

EPSP Na/Ca Depolarization Increased (more action potentials)

Question 51

``` Ligand: GABA, glycine Response: Ions Electrical response Effect on excitability ```

Answer 51

IPSP Chloride hyperpolarization Decreased (fewer aps)

Question 52

Spatial summation

Answer 52

multiple synapses IPSP or EPSP Vm effects depend on synapses

Question 53

Temporal summation

Answer 53

single synapse all EPSP or IPSP + summation if sum is positive (depolarization) - summation if sum is negative (hyperpolarization)