(Other) Muscular System

• Smooth Muscle:

  • Fibres are thin and spindle-shaped
  • No striations (stripes)
  • Mostly involuntary
  • Contracts slowly
  • Found in the circulatory system, lining of blood vessels, digestive system (oesophagus, stomach, intestines), respiratory system (controls breathing), urinary system (urinary bladder, controls urination)
• Cardiac Muscle:

  • Found only in the heart
  • Contractions pump blood throughout the body and account for the heartbeat
  • Healthy cardiac muscles NEVER fatigue
  • Involuntary
• Skeletal Muscle:

  • Fibres are long and cylindrical
  • Voluntary
  • Fast and slow twitch fibres
  • Fast contract forcefully but fatigue quickly
  • Slow contract less forcefully but fatigue slower
• Functions of the muscle:

  • Major functions: movement, maintenance of posture and muscle tone, heat production
  • Minor functions: protect the bone and internal organs
• Movement:

  • Muscles move bones by pulling, not pushing
  • Tendons anchor muscles firmly to bones (made of dense fibrous connective tissue)
  • Any movement is generally accomplished by muscles working in pairs
  • Prime Mover (agonist) is the muscle most responsible for movement
  • Antagonist is the muscle or group of muscles that work in opposite to the agonist (usually relaxes)
• Functions of Skeletal Muscle:

  • Movement: e.g. biceps contract and flex the arm (agonist), triceps relax and extend the arm (antagonist)
  • Maintenance of posture or muscle tone
  • Heat production
• Movement of Muscles:

  • Origin: attachment of the muscle to the bone that remains stationary
  • Insertion: attachment of the muscle to the bone that moves
  • Belly: fleshy part of the muscle between the tendons of origin and/or insertion
• Movement of the skeletal muscle:

  • Muscles move when the brain sends messages to the muscle
  • Always work in pairs (agonist and antagonist)
  • 2 movements of skeletal muscle: Contraction (shorten muscle) Concentric, Extension (lengthen muscle) Eccentric