Muscles- Unit 1 Biology

• 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 two 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 within muscle fibers
  • 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
• What are the differences between slow twitch and fast twitch muscle fibers?

  | Feature | Slow Twitch | Fast Twitch |

  |-----------------------|---------------------------------|---------------------------------|

  | Contraction Type | Sustained | Rapid intense |

  | Mitochondria | Lots | Few |

  | Respiration Type | Aerobic | Anaerobic |

  | Capillaries | Many | Fewer |

  | Fatigue Resistance | Does not tire easily | Tires quickly |

  | Energy Stores | Large oxygen and glucose stores | Little stored oxygen and glucose |
• What is a common question about muscle structure?

  Describe the structure of muscles
• What is a common question about muscle contraction?

  Describe how muscles contract
• What is a common question about muscle fiber types?

  Draw a table showing differences
• What type of muscle fiber is used for endurance activities?

  Slow twitch muscle fibers
• What type of muscle fiber is used for explosive activities?

  Fast twitch muscle fibers