muscle structure

• What is the A band in a sarcomere?

  Region where myosin is located
• What is actin?

  A globular protein forming helical strands
• Where is cardiac muscle found?

  Exclusively in the heart
• What happens during muscle contraction?

  I band narrows, Z lines move closer
• What is a fast twitch fibre?

  Produces fast, powerful contractions
• What is the H zone in a sarcomere?

  Central part of A band where actin is absent
• What does the I band contain?

  Only actin filaments
• What is the M line?

  Line down the center of the H zone
• What is a muscle fibre?

  Large cell-like structure in muscle
• What is a myofibril?

  Long protein structure of actin and myosin
• What is myosin?

  Fibrous protein arranged into thick filaments
• What is the sarcolemma?

  Sheath enveloping skeletal muscle fibres
• What is sarcoplasm?

  Cytoplasm of a muscle fibre
• What is skeletal muscle?

  Muscle under conscious control
• What are slow twitch fibres?

  Produce slow, less powerful contractions
• What is smooth muscle?

  Muscle found in blood vessels and gut
• What is the sarcoplasmic reticulum?

  Endoplasmic reticulum of a muscle fibre
• What is the Z line?

  Line down the center of the I band
• What are the three types of muscle?

  • Skeletal muscle (striated, voluntary)
  • Smooth muscle (involuntary)
  • Cardiac muscle
• What controls involuntary muscle?

  Autonomic nervous system
• What controls voluntary muscle?

  Somatic nervous system
• Where is smooth muscle found in the body?

  Surrounding alveoli, iris, intestines
• What is the function of smooth muscle in the intestine?

  Responsible for peristalsis
• How does cardiac muscle contract?

  Can contract without nerve impulse
• What is unique about cardiac muscle contraction?

  It is repetitive and continuous
• How do skeletal muscle cells appear under a microscope?

  They appear banded (striated)
• How do smooth muscle cells appear?

  Spindle-shaped and singly nucleated
• What connects cardiac muscle cells?

  Intercalated discs
• How are skeletal muscles attached to bones?

  By tendons
• What are antagonistic pairs of muscles?

  Muscles that work opposite each other
• What happens when the bicep contracts?

  The tricep relaxes
• What happens when the tricep contracts?

  The bicep relaxes
• What are the characteristics of fast twitch muscle fibres?

  • Lighter in color
  • Rely on anaerobic respiration
  • Contract quickly
  • Fatigue quickly
  • Fewer capillaries
• What are the characteristics of slow twitch muscle fibres?

  • Darker in color
  • Rely on aerobic respiration
  • Contract slowly
  • Slow to fatigue
  • Dense network of capillaries
• How does training affect muscle fibres?

  • Influences fibre type development
  • Increases capillaries and mitochondria
• What is the role of myofibrils in muscle contraction?

  They allow the muscle to contract
• What is the structure of a sarcomere?

  Section of myofibril between two Z lines
• What is the function of the H zone?

  Only myosin filaments are present
• What is the function of the M line?

  Attachment for myosin filaments
• What is the function of the Z line?

  Attachment for actin filaments