muscles

• What type of muscles are being discussed in the video?

  Skeletal muscles
• What does it mean for muscles to occur in antagonistic pairs?

  One muscle contracts while the other relaxes
• How can muscle movement be initiated?

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

  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 two key proteins make up myofibrils?

  Myosin and actin
• What is the role of myosin and actin in muscle contraction?

  They create the sarcomere structure
• How are myosin and actin arranged in the sarcomere?

  Actin is layered around myosin
• What happens to the I band during muscle contraction?

  It decreases in width
• What is the H zone in the sarcomere?

  Area with only myosin present
• What initiates the sliding filament theory?

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

  They bind to tropomyosin to expose 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 occurs after the myosin head forms a cross bridge with actin?

  It pulls actin filaments, creating tension
• What is released when the myosin head pulls on actin?

  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?

  It remains constant
• What happens to the Z lines during muscle contraction?

  They 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 of power
• What type of exercise are slow twitch fibers best suited for?

  Duration exercise
• Why do fast twitch fibers fatigue quickly?

  They rely on anaerobic respiration
• What is the primary energy source for fast twitch fibers during intense exercise?

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

  Increases proportion for endurance
• What is the significance of high ATP concentrations in muscle contraction?

  Essential for full muscle contraction
• What happens to muscle contraction when ATP is depleted?

  Muscle cannot contract effectively
• What is the role of mitochondria in muscle fibers?

  Produce ATP for muscle contraction
• What is the relationship between aerobic respiration and ATP production during exercise?

  Aerobic respiration produces ATP for endurance
• What happens to the I band and H zone during muscle contraction?

  Both decrease in width
• What is the function of the Z line in the sarcomere?

  Defines the boundaries of a sarcomere
• What is the significance of the M line in the sarcomere?

  It is the midpoint of the myosin filaments
• How does the sliding filament theory explain muscle contraction?

  Myosin pulls actin filaments closer together
• What is the role of the nervous system in muscle contraction?

  Stimulates release of calcium ions
• What happens to muscle fibers during anaerobic respiration?

  They produce ATP rapidly but fatigue quickly
• What is the effect of lactic acid buildup in muscles?

  Causes muscle fatigue
• How does the body adapt to endurance training?

  Increases slow twitch muscle fibers