4. Muscle Excitation Pathway

What is the first step of muscle excitation?

Action potential arrives

Where does the action potential arrive during excitation step 1?

Axon terminal

What channels open in excitation step 2?

Voltage-gated calcium channels

Which ion enters the axon terminal in excitation step 2?

Calcium

What cellular process is triggered by calcium entry in excitation step 3?

Exocytosis of vesicles

What chemical is released into the synaptic cleft during excitation step 3?

ACh

What do ACh molecules bind to in excitation step 4?

Ligand-gated sodium channels

Where are ligand-gated sodium channels located during excitation step 4?

Motor end plate

What occurs to ligand-gated channels in excitation step 5?

Channels open

Which ion enters the sarcoplasm in excitation step 5?

Sodium

What electrical event is produced by sodium entry in excitation step 6?

End plate potential

What does the abbreviation EPP stand for?

End plate potential

What type of electrical potential is an end plate potential?

Local potential

Where does the end plate potential occur?

Neuromuscular junction

What electrical state does the end plate potential bring the muscle to?

Threshold