MUSCLES

• Skeletal muscle


  • Composed of bundles/fascicles of muscle fibres/cells
• Connective tissue

  Holds the bundles together
• Connective tissue


  1. Tapers to form a tendon

  2. Tendon attaches the muscle to the bone
• Muscle fibres/cells

  • Running parallel to each other inside the bundle
• Sarcoplasm


  The substance inside the muscle cells
• Sarcoplasm


  • Contains myofibrils
• Myofibrils

  Contain myofilaments
• Types of filaments

  • Thin filament (made of actin)
  • Thick filament (made of myosin)
• Myofibrils

  • Divided into contractile units of filaments called sarcomeres
• The myofibrils are divided into contractile units of filaments called sarcomeres
• Thick filament is made up of a protein called myosin
• Thin filament is made up of a protein called actin
• There are two types of filaments made up of proteins
• Each myofibril contains myofilaments
• Within the sarcoplasm of each fibre are myofibrils
• The cells contain sarcoplasm and are wrapped in a sarcolemma
• Inside the bundle of fibres are many cells running parallel to each other
• The connective tissue tapers to form a tendon, which attaches the muscle to the bone
• These bundles are held together by connective tissue
• Skeletal muscle is composed of bundles/fascicles of muscle fibres/cells
• Properties of muscles are contractibility, extensibility, elasticity, excitable and irritable
• Connective tissue sheath called the perimysium surronds the bundles together to allow them to function as a singular unit > also allows adjacent bundles to slide pass other fibres
• Each individual cell has its own plasma membrane (sarcolemma) that surrounds it
• sheaths of connective tissue called epimysium surround muscle fibres
• muscle cell > called muscle fibre is elongated cylinder with many nuclei also a lot of mitochondria
• cells between 10-100 mircometres in diameters, but can be few millimetres to several centimetres long
• muscle cell made up of unit called myofibrils
• each myofibril is surrounded by sarcoplasmic reticulum
• myofibril contains protein filaments which are responsible for contraction
• abduction is movement away from the midline of the body
• Adduction is movement towards the midline of the body
• rotation is twisting around an axis
• Synergists are muscles that help the prime mover
• When a synergist immobilises a joint in this way, it is called a fixator
• A fixator muscle acts as a stabiliser of one part of the body during movement of another part