T-tubules

• 1. propagation of action potential along the sarcolemma
• 2. Action potential passes down T-tubules
• 3. Action potential causes sarcoplasmic reticulum to release Ca2+ which is needed for muscle contraction
• diagram

  A) sarcolemma of muscle fibre

  B) t-tubules

  C) sarcoplasmic reticulum

  D) Ca2+