Synaptic Mechanisms

Question 1

Gap Junctions

• Role
• Number of conexons
• What stage of neuronal damage

Answer 1

Role: Free passage of ions and small molecule
6 conexons
Early neuronal development so associated with congental disease

Question 2

Overview of chemical transmission

Answer 2

AP → depolarization → Ca influx → NT exocytosis → Post-synaptic receptor → Termination

Question 3

2 types of chanels

Answer 3

Ionotropic (ligand gated)

Metabotropic (G-protein)

Question 4

Excitatory ionotropic channels

Answer 4

Skeletal Ach
Neuronal Ach
Glutamate receptors (NMDA, AMPA or kainate)
Puriogenic receptors (ATP, Adenosine)

Question 5

Inhibitory ionotropic

Answer 5

GABA type A

Glycine

Question 6

Excitatory metabotropic

Answer 6

Norephrine
Serotonin receptors
Dopamine receptors
GABA type B
Cannabanoid receptors
ATP & adenosine
L-AP4 glutamate

Question 7

NT classes: Small molecules (3)

Answer 7

Amines
Glutamate
GABA
Glycine
Acetocholine

Question 8

Nt classes: Larger molecule (3)

Answer 8

Opoids
Canabonoids
Vasopresin
Gonadotropin
Oxycotin
Neuropeptide Y

Question 9

Safety function of NMJ

Answer 9

1:1

Every presyaptic AP generates AP in postsynaptic cells

Question 10

2 specializations of presynaptic terminal

Answer 10

1. Active zones
   Rows of Ca channels and ACH NT
2. SNARES
   Control fusion of NT vesicle with presynaptic membrane for exocytosis

Question 11

What does botulinum do?

Answer 11

Block excoytosis at NMJ

Question 12

What does tetanus do?

Answer 12

Activates secondary inhibitory neuron, so prevents activation

Question 13

3 cells at the NMJ

Answer 13

Spinal cord alpha neuron
Muscle cell
Inhibitory neuron

Question 14

NT at the NMJ

Answer 14

Ach

Question 15

2 post synaptic specialization

Answer 15

1. High density of receptors

2. Cell membrane invagiates to form troughs

Question 16

Ach receptors

• Channels
• What is V reversal
• Few or many vesicles

Answer 16

Na or K channel
0 mv
Many vesicles

Question 17

Desentization

Answer 17

If NT present for too long

Question 18

Quantal hypthesis

Answer 18

mean quantal content = number of vessicles X release probability

Quanta = 1 packet of NT

Question 19

Organophosphates

Answer 19

Pesticide that inactivates AchE so ACH lingers and you get desensitization

Also used therapeutically to increase Ach at the junction in patents with myasthenia gavis