Exam 2 AP Transmission

Question 1

what subunits make up the Nicotinic Ach receptor?

Answer 1

two alpha, one beta, one delta, one gamma

Question 2

what is inside the 5 subunits of the Nicotinic receptor?

Answer 2

sodium channel

Question 3

which subunits of the Nicotinic receptor have Ach binding sites?

Answer 3

the alpha subunits

Question 4

AP Transmission

Answer 4

defined as the movement of an AP from the membrane of one excitable cell to the membrane of another

Question 5

Neuronal Transmission

Answer 5

movement of an AP from the terminals of one neuron to the dendrites of another neuron

Question 6

Neuromuscular Transmission

Answer 6

movement of an AP from the terminals of a neuron to the membrane of a muscle cell

Question 7

terminal button

Answer 7

the nerve terminal membrane ends in a little bit of swelling; it comes really close to the membrane of the muscle, but it doesn’t touch it

Question 8

what is the term to describe the whole arrangement/connection between the nerve terminal and muscle membrane?

Answer 8

neuromuscular junction

Question 9

synapse

Answer 9

when the terminal of one neuron connects to the dendrite of another

Question 10

what is the specific NT in the neuromuscular junction of motor neurons and skeletal muscle?

Answer 10

acetylcholine

Question 11

what is the ACh to synaptic vessicle ratio?

Answer 11

about 10,500 ACh : 1 synaptic vessicle

Question 12

what ion channel is on the axon terminal? what does it do?

Answer 12

voltage-gated calcium channel (AKA Ca2+ ATPase); uses ATP to pump Ca2+ out of the terminal and into the surrounding interstitial space creating calcium gradient across membrane (high concentration outside of membrane, low concentration inside membrane)

Question 13

where is NT synthesized?

Answer 13

either in the cell body of the pre-synaptic neuron or the terminal button itself depending on the NT

Question 14

where is the precursor peptide for NT synthesized?

Answer 14

rough ER

Question 15

where is the precursor peptide for NT packaged?

Answer 15

golgi apparatus

Question 16

where is the precursor peptide for NT trafficked?

Answer 16

in microtubules down to the terminal button (from golgi apparatus in soma)

Question 17

where is ACh synthesized?

Answer 17

terminal button

Question 18

ACh synthesis in terminal button steps

Answer 18

1. Coenzyme A = taken up by mitochondria where its assimilated
2. comes out of mitochondria as Acetyl-CoA and is transported back out into the cytoplasm
3. Acetyl-CoA combines with choline enzymatically to form ACh
4. ACh = packaged in the synaptic vessicle

Question 19

how is ACh packaged in the synaptic vesicles?

Answer 19

the synaptic vesicles have transporters (particularly proton ATPase and hydrogen ATPase); proton ATPase uses ATP to pump protons/H+ into the vesicles; the protons tend to diffuse out across the vesicle membrane (a transport protein exchanges protons for ACh)

Question 20

what is ACh made from?

Answer 20

choline and acetyl CoA

Question 21

how is ACh dumped via exocytosis?

Answer 21

Ca2+ activates a set of proteins called SNARE proteins; when activated, they change shape and grab/twist each other; the twisting pulls the synaptic vesicles to the membrane, causes them to fuse and the vesicles open up and dump ACh into the synaptic cleft via exocytosis

Question 22

SNARE proteins

Answer 22

synaptobrevin: on membrane of synaptic vessicle
SNAP-25 and syntaxin: associated with the inside of the terminal button membrane.