muscles

• What are muscles made up of?

  Bundles of muscle fibers
• What is a muscle fiber?

  It is the actual muscle cell
• What are myofibrils?

  Long thin structures in muscle fibers
• What are sarcomeres?

  Sections that make up myofibrils
• What types of filaments are in sarcomeres?

  Myosin and actin filaments
• Describe the structure of muscles.

  • Muscles are made of bundles of muscle fibers
  • Each fiber is a muscle cell
  • Myofibrils are long thin structures
  • Myofibrils consist of sarcomeres
  • Sarcomeres contain myosin and actin filaments
• How do muscles contract?

  Sarcomeres get shorter during contraction
• What is the length range of sarcomeres during contraction?

  Between 2.2 and 3 micrometers
• What happens to actin filaments during muscle contraction?

  They slide between myosin filaments
• What is the role of special proteins in muscle contraction?

  They drag the filaments together
• What are the two types of muscle fibers?

  Slow twitch and fast twitch
• Describe slow twitch muscle fibers.

  • Slow sustained contraction for long periods
  • Lots of mitochondria
  • High aerobic respiration
  • Many capillaries for oxygen supply
  • Large oxygen and glucose stores
• Describe fast twitch muscle fibers.

  • Rapid intense contractions in short bursts
  • Few mitochondria
  • Energy from anaerobic respiration
  • Produces lactic acid
  • Tires quickly with little stored oxygen
• What type of athlete typically has more slow twitch fibers?

  Endurance athletes like marathon runners
• What type of athlete typically has more fast twitch fibers?

  Sprinters and explosive athletes