Muscles

• Antagonistic pairs

  • The agonist muscle contracts and shortens while the antagonist muscle relaxes and lengthens
• Myofibrils

  • Fused cells that share nuclei and cytoplasm called sarcoplasm
  • High number of mitochondria for aerobic respiration
  • Made of actin and myosin protein filaments
• Why do myofibrils have lots of mitochondria?  

  • To make lots ATP in aerobic respiration which is broken down and releases energy for muscle contraction
• Actin

  • Thin protein filaments in the myofibrils
• Myosin

  • Thick protein filaments in the myofribrils
• Sarcomere

  • A section of a myofibril responsible for sliding filament theory