Flashcards in this deck (29)

• What is the hierarchical structure of skeletal muscle?

  • Whole muscle (cm)
  • Muscle fascicle (mm)
  • Muscle fiber (µm x 100)
  • Myofibril (µm)
  anatomy muscle skeletal
• What is a sarcomere?

  • Basic repeating unit of structure
  • Diameter = 1 μm
  • Contains myofilaments (nm)
  anatomy sarcomere
• What are the two major myofilaments in a sarcomere?

  • Actin (thin)
  • Myosin (thick)
  anatomy myofilaments
• What is the diameter of a sarcomere?

  1 μm
  anatomy sarcomere
• What are the components of the hierarchical structure of skeletal muscle?

  • Whole muscle
  • Muscle fascicle
  • Muscle fiber
  • Myofibril
  anatomy muscle structure
• What does the sarcomere contain?

  • Myofilaments
  anatomy sarcomere
• What is the function of actin in a sarcomere?

  It is a thin myofilament.
  anatomy myofilaments
• What is the function of myosin in a sarcomere?

  It is a thick myofilament.
  anatomy myofilaments
• What is the scale of muscle structure from whole muscle to myofibril?

  • Whole muscle: cm
  • Muscle fascicle: mm
  • Muscle fiber: µm x 100
  • Myofibril: µm
  anatomy muscle scale
• What is the largest structural unit of skeletal muscle?

  Whole muscle (cm)
  anatomy muscle
• What is the second level of structure in skeletal muscle?

  Muscle fascicle (mm)
  anatomy muscle
• What is the size of a muscle fiber?

  ~100 µm
  anatomy muscle
• What is the size of a myofibril?

  ~1 µm
  anatomy muscle
• How many sarcomeres can be found in a single muscle fiber?

  Up to 100,000 sarcomeres
  anatomy muscle
• What is the typical number of fibers per muscle in a developing fetus?

  ~50 fibers/muscle
  anatomy muscle
• What is the typical number of fibers per muscle in an untrained adult?

  ~2,000 fibers/muscle
  anatomy muscle
• How many sarcomeres can be present in a single muscle?

  Up to 200 million sarcomeres
  anatomy muscle
• What is the function of actin in a sarcomere?

  Thin filament involved in muscle contraction
  anatomy muscle
• What is the function of myosin in a sarcomere?

  Thick filament that interacts with actin during contraction
  anatomy muscle
• What are the dark bands in a sarcomere?

  • A band: myosin
  • H Zone: myosin only (no actin)
  • M line: centerline of myosin
  biology muscle sarcomere
• What are the light bands in a sarcomere?

  • I band: actin only
  • Z-line: thin dark line in center (now known as Z-disk)
  biology muscle sarcomere
• What is located in the H zone of a sarcomere?

  • Myosin only (no actin)
  • M line: region (centerline of myosin)
  biology muscle sarcomere
• What is the Z-line in a sarcomere?

  • Thin dark line in center of I band
  • Now known as a Z-disk (3-D structure)
  biology muscle sarcomere
• What does the A band in a sarcomere contain?

  • Myosin
  anatomy muscle
• What is found in the H zone of a sarcomere?

  • Myosin only
  • M line (centerline of myosin)
  anatomy muscle
• What does the I band in a sarcomere contain?

  • Actin only
  anatomy muscle
• What is the overall structure of a sarcomere?

  Alternating light/dark bands
  anatomy muscle
• What is the significance of the Z-disk?

  It contributes to the 3-D structure of the sarcomere.
  anatomy muscle
• What does the electron microscopy image of a sarcomere show?

  It shows alternating light and dark bands.
  anatomy muscle