Locomotion

• Movement

  • One of the significant features of living beings
  • Animals and plants exhibit a wide range of movements
• Types of movement

  • Streaming of protoplasm in Amoeba
  • Movement of cilia, flagella and tentacles
  • Movement of limbs, jaws, eyelids, tongue
• Locomotion

  Voluntary movements that result in a change of place or location
• Locomotory movements

  • Walking
  • Running
  • Climbing
  • Flying
  • Swimming
• Locomotory structures need not be different from those affecting other types of movements
• Movements and locomotion cannot be studied separately
• Reasons for locomotion

  • Search of food, shelter, mate, suitable breeding grounds, favourable climatic conditions
  • Escape from enemies/predators
• Types of movement in human body

  • Amoeboid
  • Ciliary
  • Muscular
• Amoeboid movement


  Effected by pseudopodia formed by the streaming of protoplasm
• Ciliary movement


  • Coordinated movements of cilia in the trachea help in removing dust particles and some foreign substances
  • Facilitates passage of ova through the female reproductive tract
• Muscular movement

  Contractile property of muscles effectively used for locomotion and other movements
• Locomotion requires a perfect coordinated activity of muscular, skeletal and neural systems
• Muscle

  • Specialised tissue of mesodermal origin
  • 40-50% of the body weight of a human adult is contributed by muscles
  • Have properties like excitability, contractility, extensibility and elasticity
• Types of muscles based on location

  • Skeletal
  • Visceral
  • Cardiac
• Skeletal muscles

  • Closely associated with the skeletal components of the body
  • Striated appearance under the microscope
  • Activities under voluntary control of the nervous system
  • Involved in locomotory actions and changes of body postures
• Visceral muscles

  • Located in the inner walls of hollow visceral organs
  • No striations, smooth appearance
  • Activities not under voluntary control of the nervous system
  • Assist in transportation of food through digestive tract and gametes through genital tract
• Cardiac muscles


  • Muscles of the heart
  • Striated appearance
  • Involuntary in nature, not directly controlled by the nervous system
• Skeletal muscle structure

  • Muscle fibre is a syncitium with many nuclei
  • Presence of parallelly arranged filaments called myofilaments or myofibrils
  • Myofibrils have alternate dark and light bands
• Actin and myosin


  • Proteins that give the striated appearance to muscle fibres
  • Actin is the thin filament, myosin is the thick filament
• Sarcomere


  Functional unit of contraction in a myofibril
• Sliding filament theory


  Contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments
• Muscle contraction

  1. Neural signal from CNS

  2. Release of neurotransmitter at neuromuscular junction

  3. Generation of action potential in sarcolemma

  4. Release of calcium ions into sarcoplasm

  5. Binding of calcium to troponin

  6. Exposure of actin binding sites

  7. Formation of cross-bridges between actin and myosin

  8. Sliding of thin filaments over thick filaments

  9. Shortening of sarcomere

  10. Pumping back of calcium ions into sarcoplasmic reticulum
• Red and white muscle fibres

  • Red fibres have high myoglobin content and mitochondria, are aerobic
  • White fibres have low myoglobin and mitochondria, are anaerobic
• Repeated muscle activation can lead to accumulation of lactic acid, causing fatigue
• Skeletal system


  • Framework of bones and cartilages
  • Significant role in movement
  • 206 bones and a few cartilages in human beings
• Divisions of skeletal system

  • Axial skeleton
  • Appendicular skeleton
• Axial skeleton

  • 80 bones distributed along the main axis of the body
  • Includes skull, vertebral column, sternum and ribs
• Skull

  • Composed of 22 bones
  • 8 cranial bones form the cranium
  • 14 facial bones form the front part of the face
• Skeletal system


  Framework of bones and a few cartilages
• Skeletal system

  • Significant role in movement shown by the body
  • Consists of 206 bones and a few cartilages
  • Grouped into two principal divisions - the axial and the appendicular skeleton
• Axial skeleton


  • Skull
  • Vertebral column
  • Sternum
  • Ribs
• Skull

  Composed of two sets of bones - cranial and facial, totaling 22 bones
• Cranial bones

  8 in number, form the hard protective outer covering, cranium for the brain
• Facial region


  Made up of 14 skeletal elements which form the front part of the skull
• Hyoid bone

  Single U-shaped bone at the base of the buccal cavity, included in the skull
• Ear ossicles


  Three tiny bones - Malleus, Incus and Stapes, in the middle ear
• Vertebral column

  Formed by 26 serially arranged units called vertebrae, dorsally placed
• Vertebrae


  Each has a central hollow portion (neural canal) through which the spinal cord passes
• Regions of vertebral column

  • Cervical (7)
  • Thoracic (12)
  • Lumbar (5)
  • Sacral (1-fused)
  • Coccygeal (1-fused)
• Vertebral column


  • Protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back