Exam 2 AP Transmission Flashcards
what subunits make up the Nicotinic Ach receptor?
two alpha, one beta, one delta, one gamma
what is inside the 5 subunits of the Nicotinic receptor?
sodium channel
which subunits of the Nicotinic receptor have Ach binding sites?
the alpha subunits
AP Transmission
defined as the movement of an AP from the membrane of one excitable cell to the membrane of another
Neuronal Transmission
movement of an AP from the terminals of one neuron to the dendrites of another neuron
Neuromuscular Transmission
movement of an AP from the terminals of a neuron to the membrane of a muscle cell
terminal button
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
what is the term to describe the whole arrangement/connection between the nerve terminal and muscle membrane?
neuromuscular junction
synapse
when the terminal of one neuron connects to the dendrite of another
what is the specific NT in the neuromuscular junction of motor neurons and skeletal muscle?
acetylcholine
what is the ACh to synaptic vessicle ratio?
about 10,500 ACh : 1 synaptic vessicle
what ion channel is on the axon terminal? what does it do?
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)
where is NT synthesized?
either in the cell body of the pre-synaptic neuron or the terminal button itself depending on the NT
where is the precursor peptide for NT synthesized?
rough ER
where is the precursor peptide for NT packaged?
golgi apparatus
where is the precursor peptide for NT trafficked?
in microtubules down to the terminal button (from golgi apparatus in soma)
where is ACh synthesized?
terminal button
ACh synthesis in terminal button steps
- Coenzyme A = taken up by mitochondria where its assimilated
- comes out of mitochondria as Acetyl-CoA and is transported back out into the cytoplasm
- Acetyl-CoA combines with choline enzymatically to form ACh
- ACh = packaged in the synaptic vessicle
how is ACh packaged in the synaptic vesicles?
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)
what is ACh made from?
choline and acetyl CoA
how is ACh dumped via exocytosis?
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
SNARE proteins
synaptobrevin: on membrane of synaptic vessicle
SNAP-25 and syntaxin: associated with the inside of the terminal button membrane.
