Answer: Acetylcholine.
- A Adrenaline
- B Acetylcholine
- C Dopamine
- D Serotonin
Correct answer: B. Acetylcholine
Explanation: Motor neurons release acetylcholine at the neuromuscular junction, exciting the muscle fibre membrane.
A sarcomere (Z line to Z line): during contraction the I band and H zone shorten as thin filaments slide over thick, while the A band stays the same length. Image: SlothMcCarty, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.