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 two types of filaments are in sarcomeres?

  Myosin and actin filaments
• How do muscles contract?

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

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

  They slide between myosin filaments
• What role do special proteins play in muscle contraction?

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

  Slow twitch and fast twitch fibers
• What characterizes slow twitch muscle fibers?

  They sustain contraction for long periods
• What do slow twitch fibers have a lot of?

  Lots of mitochondria
• How do slow twitch fibers generate energy?

  Through aerobic respiration
• What is the function of capillaries in slow twitch fibers?

  To supply oxygen and remove CO2
• What characterizes fast twitch muscle fibers?

  They contract rapidly in short bursts
• How do fast twitch fibers generate energy?

  Through anaerobic respiration
• What do fast twitch fibers produce as a byproduct?

  Lactic acid
• Why do fast twitch fibers tire quickly?

  They have little stored oxygen and glucose
• How do different athletes vary in muscle fiber composition?

  They have different proportions of slow and fast twitch fibers
• What type of muscle fibers do endurance athletes typically have?

  More slow twitch muscle fibers
• What type of muscle fibers do sprinters typically have?

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

  • Slow twitch:
  • Sustained contraction
  • Lots of mitochondria
  • Aerobic respiration
  • Many capillaries
  • Large oxygen and glucose stores
  • Fast twitch:
  • Rapid, intense contractions
  • Few mitochondria
  • Anaerobic respiration
  • Fewer capillaries
  • Little stored oxygen and glucose
• What is a common question regarding muscle structure?

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

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

  Draw a table showing differences
• What types of athletes have an abundance of slow twitch fibers?

  Endurance athletes like marathon runners
• What are the three types of muscle tissue?

  Skeletal, cardiac, smooth

  
• What is the appearance of skeletal muscle under a microscope?

  Striped appearance due to muscle filaments
• How many nuclei does skeletal muscle have?

  More than one nucleus
• What unique feature does cardiac muscle have compared to skeletal muscle?

  Cross branches between different fibrils
• What is the function of cardiac muscle?

  Pumps the heart with rhythmic contractions
• What shape are the cells in smooth muscle?

  Cigar shaped
• Why are no stripes visible in smooth muscle under a microscope?

  Filaments are not organized into clear lines
• Where is smooth muscle found in the body?

  In internal organs
• What is the primary function of smooth muscle in the digestive system?

  Moves food by peristalsis
• What is the I band in skeletal muscle structure?

  Light-colored stripe with only actin filaments

  
• What does the A band represent in skeletal muscle?

  Dark stripes with both actin and myosin
• What happens to the H zone during muscle contraction?

  It gets narrower
• What is the role of the Z disc in a sarcomere?

  Attachment point for actin filaments
• What is the function of the sarcoplasmic reticulum?

  Stores calcium ions for muscle contraction