Lecture 10

Question 1

what neurotransmitter is used to activate fiber contraction

Answer 1

acetylcholine

Question 2

where are ACH receptors anchored

Answer 2

at post synaptic cell of NMJ

Question 3

what happens to ACH receptors when a motor neuron approaches

Answer 3

they aggregate to one area of the newly forming NMJ

Question 4

what are the possible results of the NT binding in synaptic transmission

Answer 4

either converts signal back to electrical signal to finish its communication pathway or results in activating cell signaling pathways affecting function in post synaptic cell

Question 5

what are the 2 classes of NTs

Answer 5

• large peptide

- small amines and amino acids

Question 6

what is an example of a large peptide and a small amine

Answer 6

large peptide- substance P , enkephalin

small amine- acetylcholine, glycine

Question 7

where does synthesis occur in large peptides and small amines

Answer 7

large peptides- cell body

small amine- terminal bouton

Question 8

where does trafficking occur in large peptides and small amines

Answer 8

large peptides- large vesicles, axonal transport

small amines- small vesicles

Question 9

how are vesicles recycled in large peptides and small amines

Answer 9

large peptides- vesicle component back to cell body for reuse
small amines- vesicles and substrates recycled at bouton

Question 10

what are the post synaptic effects of large peptides and small amines

Answer 10

large peptides- metabotropic

small amines- can either be inotropic or local metabotropic

Question 11

what are two structural ways the NMJ ensures depolarization

Answer 11

• presynaptic structure fits snugly into post synaptic cleft so ACh will stay close
• the active zones have matched lines of vesicles with Its of pre synaptic cleft to lines of their receptors on the post synaptic cleft

Question 12

what do SNARE proteins do

Answer 12

pull vesicles down to the presynaptic membrane enabling fusion and release of NT into synaptic cleft

Question 13

what kind of SNARE protein is SNAP25

Answer 13

target

Question 14

what kind of SNARE protein in syntaxin

Answer 14

target

Question 15

what kind of SNARE protein is synaptobrevin

Answer 15

vesicle

Question 16

what is the SNARE mechansim

Answer 16

• the n-sec-1 regulatory proteins bind to syntax, prohibiting interaction between SNARE proteins
• once removed by phosphorylation the 3 SNAREs intertwine and tether vesicle to the membrane
• local increases in Ca2+ bind to and activate synaptotagmin which forms pore in the vesicle and membrane to allow release of NT

Question 17

what happens with SNARE mechanism once NT is released

Answer 17

• ATP is required to enable untwisting of SNAREs

- vesicle membrane is recycled

Question 18

what happens with Botox

Answer 18

• botox inhibits muscle contraction by binding to and cleaning syntax
• this prevents tethering and fusion of vesicle to pre-synaptic membrane, preventing the release of Ash at the NMJ