Synaptic Transmission

Question 1

Difference between chemical and electrical synapses?

Answer 1

Electrical are simpler structure and function
Faster
Passive signal transmission
Bidirectional
Minority but important in development
Allow synchronised activity among population of neurons

Question 2

How many neurons in human brain?

Answer 2

More than 80 billion

Question 3

How wide is synaptic cleft?

Answer 3

20-50nm

Question 4

How wide are synaptic vesicles?

Answer 4

50nm

Question 5

Secretory granules diameter?

Answer 5

100nm, contain soluble proteins

Question 6

What is neuromodulation?

Answer 6

Alters the presynaptic cells ability to release more neurotransmitter or the post synaptic cells ability to respond

Question 7

One quantum generates?

Answer 7

Miniature end plate potential

Question 8

Criteria of neurotransmitter?

Answer 8

Made in neuron
Present in presynaptic terminal and release in sufficient amounts to exert a defined effect of postsynaptic neuron
When administered exogenously it mimics the endogenous effect
Specific mechanism for removing it from synaptic cleft

Question 9

Pool of vesicles anchored to cytoskeleton are done by?

Answer 9

Synapsin

Question 10

What does calcium do in presynaptic neuron?

Answer 10

Calcium activates calcium calmodulin activated kinase II CAMKII which phosphorylate synapsin
Which can no longer bind to cytoskeleton so vesicles dock to active zone

Question 11

What docks vesicles to plasma membrane at active zone?

Answer 11

SNARE complex , Soluble NSF Attachment Protein Receptor

Question 12

What happens at exocytosis?

Answer 12

Synaptobrevin from vesicle joins with syntax in and SNAP 25 to form SNARE complex

This causes calcium to enter, which binds to synaptotagmin, which catalyses membrane fusion by binding to SNARES and plasma membrane

Question 13

What is priming?

Answer 13

Partial assembly of SNARE complexes

Question 14

What are the 2 deadliest toxins?

Answer 14

Botulinum toxin and tetanus toxin causing proteolysis to block neurotransmitter release
Botulinum- decreases neuromuscular transmission of ACh
Tetanus- decreases GABA, gly interneurons at spinal cord

Question 15

Treatment of muscle spasms?

Answer 15

Botox

Question 16

What does lambert Eaton myasthenic syndrome attack?

Answer 16

Presynaptic ca channels

Question 17

Latrotoxin causes?

Answer 17

Vesicle fusion, causing release of neurotransmitter and hyperactivity

Question 18

Congenital myasthenic syndromes result in?

Answer 18

Impaired vesicle recycling

Question 19

What do vesicular transporters do?

Answer 19

ATPase pump loads up vesicles with H making them acidic i.e 1 glutamate traded for 1 H

Question 20

What do plasma membrane transporters do?

Answer 20

Powered by electrochemical gradient
Sodium higher outside and K inside
So glutamate is cotransported with 2 Na

Question 21

What do amphetamines and cocaine do?

Answer 21

Block certain transporters