Synaptic Transmission

Question 1

Electrical Synapses

Answer 1

not unique to Neurons
have gap junctions - distance 3nm
6 connexins = 1 connexon
2 connexons = 1 Gap Junction
pore diameter 1-2nm
fast & faithfull transmission but no modulation

Question 2

Chemical Synapses

Answer 2

axodendritic-,axosomatic-,axoaxonic-synapses
Have 3 compartements presynaptic active zone, synaptic cleft & postsynaptic density

Question 3

Active Zone

Answer 3

initiates synaptic vesicle release due to Ca2+ influx, ahs machinery for exocytosis and endocytosis

Question 4

Synaptic cleft

Answer 4

Resemble tight junction -25nm roughly 1000 adhesion proteins

Question 5

Postsynaptic density

Answer 5

generates response to neurotransmitter release, stabilizes receptors and ion channels by scaffold proteins >200 different proteins

Question 6

Sir John Eccles

Answer 6

Postulated the existence of IPSPs and EPSPs

Question 7

Neurotransmitters

Answer 7

Three chemical classes
1. Amino Acids( Glutamat,Glycine,GABA)
2. Amines( Acetyl choline, dopamine, serotonine, adrenaline)
3. Peptides( somatostatin, neuropeptide Y)
-> GABA and Amines are only synthesized in Neurons

Question 8

Neurotransmitter release

Answer 8

Exocytosis initiated by opening of Voltage gated Ca2+ channels > leads to membrane fusion -0.2ms

Question 9

Membrane Fusion

Answer 9

Vesicle(V-SNARES) and active zone plasma membrane(t-SNARES)
Homologous sequence of 70 amino acids (SNARE motif)
SNARE complex results from interaction of 4 parallel helices

Question 10

Neurotransmitter release Types

Answer 10

Reuse (Kiss & stay)
Reuse (Kiss & run)
Endosomal recycling

Question 11

Biochemistry of Neurotransmitter synthesis

Answer 11

Tyrosin>L-DOPA>Dopamin>Noradrenalin>Adrenalin
Tryptophan>5-Hydroxytryptophan>5-Hydroxytryptamin(Serotonin)

Question 12

Na/K+ transport rate and stöchiometrie

Answer 12

3 sodiums out 2 potassium in
pump / ion channel
10-500 Na/s / 100000 Na/s