Muscles and motility

• What is a lever?


  A simple machine that amplifies the input force about an axis point to overcome resistance
• What is a joint?


  A junction between two or more bones
• What type of skeleton do vertebrates have?


  An endoskeleton
• How are muscles anchored to bones?

  Muscles are anchored to bones by tendons
• What role do bones play in relation to muscles?


  Bones act as levers as muscles contract
• What type of skeleton do arthropods have?


  A chitinous exoskeleton
• What connects bones in synovial joints?

  Synovial joints connect bones with a fibrous capsule
• What are the structures found in a synovial joint?


  • Muscles contract to generate force for movement
  • Bones act as levers, anchored to muscles
  • Cartilage reduces friction and absorbs shock
  • Synovial fluid lubricates cartilage and provides nutrients
  • Synovial capsule seals fluid and promotes stability
  • Tendons anchor muscles to bones
  • Ligaments connect bones to bones and stabilize joints
• What type of joint is the hip joint?

  A synovial ball and socket joint
• How does the ball fit into the hip joint?


  The ball on the femur fits into the acetabulum on the pelvis
• What covers the socket area and femoral head in the hip joint?


  Cartilage
• What stabilizes the hip joint?

  The joint capsule
• What is the function of synovial fluid in the hip joint?


  It lubricates the joint
• What is the range of motion in hip joints?


  Hip joints allow movement in one direction
• What type of joint allows the widest range of motion?

  Ball and socket joints
• What are the characteristics of intercostal muscles?


  • Antagonistic muscles
  • Internal intercostals are diagonal and deeper, increasing control and force
  • External intercostals are parallel and surface-level, increasing movement speed
  • Internal contraction lowers ribcage and stretches external
• What is goniometry?


  Measurement of range of joint movements
• What are some reasons for locomotion in animals?

  • Ants forage for food
  • Pronghorns escape danger
  • Male birds of paradise search for a mate
  • Monarch butterflies migrate
• What are the common characteristics of all mammals?


  • Have lungs
  • Are endotherms
  • Have body hair at some stage
  • Produce milk from mammary glands
• What are adaptations of marine mammals for movement?


  • Streamlined bodies to reduce drag
  • Modified pentadactyl limbs for swimming
  • Fluke or tail for propulsion
  • Dorsal fins for stability
  • Blubber for buoyancy
  • Modified airways for breathing between dives
• What is the function of blowholes in marine mammals?


  They allow breathing while mostly underwater
• How do muscular control of nostrils benefit marine mammals?


  It prevents water from entering
• What is the purpose of large lung capacity in marine mammals?


  It increases oxygen store
• What is the role of rigid bronchial tubes in marine mammals?


  They withstand high water pressure
• What is movement defined as?


  A change in position of the body or a body part
• What are some adaptations for movement in different organisms?

  • Single-celled organisms like paramecia have cilia
  • Plants exhibit phototropism
  • Adult barnacles are sessile but can move their coral fans
  • Mammals have muscles attached to bones
• What are the components involved in muscle contraction?

  1. Sarcolemma: plasma membrane of muscle fibers
  2. Sarcoplasm: cytoplasm of muscle fiber
  3. Sarcoplasmic reticulum: stores calcium ions
  4. Mitochondria: site of aerobic respiration
  5. Myofibrils: contractile units of muscle
  6. Sarcomeres: strands of actin and myosin proteins
• What is the sliding filament theory?


  • Myosin pulls actin towards the sarcomere center
  • Shortens the sarcomere and muscle fiber length
  • Myosin heads bind to actin, creating cross bridges
  • Actin slides along myosin with energy from ATP
• What are the stages of sarcomere contraction?


  1. ATP attaches to myosin head
  2. Myosin head detaches from actin
  3. ATP is hydrolyzed to ADP and Pi
  4. Myosin head attaches to actin binding site
  5. Myosin head pushes actin during power stroke
  6. Myosin head detaches and reattaches to next binding site
  7. Cycle repeats
  8. ATP is used to break cross bridges and move myosin heads
• What is the role of tropomyosin and troponin in muscle contraction?


  • Calcium ions bind to troponin
  • Tropomyosin moves, exposing myosin binding sites on actin
  • Myosin heads form cross bridges and pivot actin towards the center
• How does skeletal muscle contract?

  1. Sliding filament model
  2. Action potential arrives at neuromuscular junction
  3. Acetylcholine is released and binds to receptors
  4. Sodium ions flow in, causing action potential
  5. Sarcoplasmic reticulum releases calcium ions
  6. Myosin forms cross bridge
  7. Myosin moves actin using ATP
  8. ATP binding releases myosin from actin
  9. Cycle repeats
• What is the function of titin in muscle fibers?

  • A long fibrous elastic protein
  • Acts as a molecular spring
  • Prevents over-extension
  • Helps sarcomeres recoil
• What is the role of a motor neuron?


  • Transmits action potential from CNS to effector
  • Dendrites receive information from other neurons
  • Cell body processes information and decides on action potential
  • Axon covered in Schwann cells for action potential travel
  • Myelin sheath maintains action potential strength
  • Axon terminals release neurotransmitters
• What is a neuromuscular junction?


  A synapse between an axon terminal of a motor neuron and muscle fiber
• What is a synapse?


  A junction between two neurons or a motor neuron and muscle fiber