skeletal muscle

• What type of muscle pairs do skeletal muscles occur in?

  Antagonistic pairs
• What happens when one muscle in an antagonistic pair contracts?

  The other muscle relaxes
• How can muscle movement occur?

  Automatically or through conscious thought
• What is the structure within skeletal muscle that is focused on?

  Myofibril
• What is the cytoplasm of muscle cells called?

  Sarcoplasm
• Why do myofibrils have a high number of mitochondria?

  ATP is essential for muscle contraction
• What are the two key proteins in myofibrils?

  Myosin and actin
• What do myosin and actin collectively create?

  Sarcomere
• How are myosin and actin arranged in the sarcomere?

  Actin layers surround myosin
• What happens to the I band during muscle contraction?

  The I band decreases in width
• What is the H zone in the sarcomere?

  Area with only myosin present
• What initiates muscle contraction according to the sliding filament theory?

  Action potential reaching the muscle
• What role do calcium ions play in muscle contraction?

  They bind to tropomyosin, exposing binding sites
• What is the function of tropomyosin in muscle contraction?

  It covers binding sites on actin
• What happens when calcium ions bind to tropomyosin?

  Tropomyosin moves, exposing binding sites
• What is formed when myosin heads attach to exposed binding sites on actin?

  A cross bridge
• What is released when the myosin head pulls at an angle?

  ADP and inorganic phosphate (Pi)
• What happens when a new ATP molecule binds to the myosin head?

  Myosin head detaches from actin
• What enzyme hydrolyzes ATP attached to the myosin head?

  ATPase
• What is the role of phosphocreatine in muscle contraction?

  It helps regenerate ATP from ADP
• What happens to the A band during muscle contraction?

  The A band remains constant
• What happens to the Z lines during muscle contraction?

  The Z lines move closer together
• What are the differences between slow twitch and fast twitch muscle fibers?

  Slow Twitch Fibers:

  • Large stores of myoglobin
  • Rich blood supply
  • Higher proportion of mitochondria
  • Contract slower, good for endurance

  
  

  Fast Twitch Fibers:

  • Thicker muscles with more myosin
  • Large stores of glycogen and phosphocreatine
  • High concentration of anaerobic respiration enzymes
  • Contract faster, good for short bursts
• What type of respiration do slow twitch fibers primarily use?

  Aerobic respiration
• What type of respiration do fast twitch fibers primarily use?

  Anaerobic respiration
• How does training affect the proportion of slow twitch fibers?

  Increases in endurance athletes
• What is the consequence of anaerobic respiration in fast twitch fibers?

  Lactic acid builds up, causing fatigue
• Why do sprinting runners rely on anaerobic respiration?

  They need ATP rapidly for short bursts
• What is the role of myoglobin in slow twitch fibers?

  It stores oxygen for aerobic respiration
• What is the significance of having many mitochondria in muscle fibers?

  They produce ATP for muscle contraction
• What happens to muscle fibers when they are stimulated by the nervous system?

  Calcium ions are released, initiating contraction
• What is the relationship between ATP and muscle contraction?

  ATP is essential for muscle contraction
• What is the effect of muscle contraction on the sarcomere structure?

  The sarcomere shortens as actin slides
• What is the role of the nervous system in muscle contraction?

  It stimulates the release of calcium ions
• What happens to the muscle when ATP is depleted?

  The muscle cannot contract effectively
• What is the importance of aerobic respiration in muscle function?

  It provides sustained energy for contraction
• How does anaerobic respiration affect muscle performance?

  It leads to quick fatigue due to lactic acid
• What is the role of enzymes in muscle contraction?

  They facilitate the hydrolysis of ATP
• What is the significance of the sliding filament theory?

  It explains how muscles contract at the molecular level
• What happens to the muscle fibers during intense exercise?

  They rely on anaerobic respiration for ATP