the muscular system.pptx

• What do skeletal muscles produce to create movement?

  Movement by exerting a force on a tendon
• How do tendons contribute to movement?

  Tendons pull structures such as bones or skin
• How many joints do most muscles cross?

  At least one joint
• What is the "belly" of a muscle?

  The fleshy portion of the muscle between the tendons
• What happens when muscles that move a body part cross a joint?

  They can cause movement at that joint
• What is the muscle origin?

  The muscular attachment point that is fixed or stable during contraction
• Where is the muscle origin usually located?

  On the proximal end of a muscle or closer to midline
• What is the muscle insertion?

  The attachment point on bone or soft tissue that moves during contraction
• What happens to the insertion point during muscle contraction?

  It moves toward the origin point
• What are lever systems in the context of muscles?

  Bones act as levers and joints act as fulcrums
• What are the two different forces acting on a lever?

  Effort and load (resistance)
• What does the effort represent in a lever system?

  The force exerted by the muscle contraction
• What does the load represent in a lever system?

  The weight of the body part or resistance of an object
• When does motion occur in a lever system?

  When the effort applied to the insertion overcomes the load
• To what percentage can muscles contract from their resting length?

  About 70%
• How are muscle fibers arranged within a muscle fascicle?

  All muscle fibers are arranged in the same orientation
• What are the different patterns of muscle fascicle arrangement?

  • Parallel
  • Fusiform (spindle-shaped)
  • Circular
  • Triangular
  • Pennate (feather-shaped)
• How does the arrangement of muscle fascicles affect muscle performance?

  It affects the muscle’s power and range of motion
• What is the relationship between fiber length and range of motion?

  The longer the fiber, the greater the range of motion
• Can a short fiber contract as forcefully as a long fiber?

  Yes, but it results in less range of motion
• What determines the power of a muscle?

  The cross-sectional area of the muscle
• How does the number of fibers per cross-sectional area affect muscle power?

  The more fibers per cross-sectional area, the more power
• How do muscles coordinate movements?

  • Movements often involve several muscles acting as a group
  • Most muscles are arranged in opposing pairs at joints
  • Example pairs: Flexors-extensors, abductors-adductors
  • Prime mover (agonist) contracts to cause an action
  • Antagonist stretches and yields to the prime mover
• What is the role of synergists in muscle coordination?

  They stabilize joints to prevent unwanted movements
• What happens if opposing muscles contract with the same force?

  No movement occurs
• What are fixators in muscle coordination?

  Muscles that stabilize the origin of the prime mover
• How do fixators contribute to muscle movement?

  They allow for more efficient movement of the prime mover
• What is an example of fixators in action?

  Fixators hold the scapula in place while the deltoid contracts
• What roles do prime movers, antagonists, synergists, and fixators play in muscle movement?

  • Prime movers: cause an action
  • Antagonists: stretch and yield to prime movers
  • Synergists: stabilize joints
  • Fixators: stabilize the origin of prime movers
• What can cause exercise-induced muscle damage?

  Intense exercise
• What can be seen on an electron micrograph after muscle damage?

  Torn sarcolemma, damaged myofibrils, disrupted Z discs
• What elevated blood levels can indicate muscle damage?

  Myoglobin and creatine kinase
• What is delayed onset muscle soreness (DOMS)?

  Soreness, stiffness, tenderness, and swelling after exercise
• When does DOMS typically occur?

  12-48 hours after strenuous exercise
• What is likely associated with DOMS?

  Microscopic muscle damage
• What can occur during microscopic repair of muscle damage?

  New regions of sarcolemma are formed and more muscle proteins are synthesized
• What happens to muscle mass between the ages of 30-50?

  There is a slow progressive loss of muscle mass
• What replaces muscle tissue as it is lost with aging?

  Fibrous connective tissue and adipose tissue
• What percentage of muscle mass is typically lost between the ages of 30-50?

  Approximately 10%
• What factors contribute to the loss of muscle mass with aging?

  Decreased levels of physical activity