movement in humans

• Skeleton

  Consists of two types of tissues: bone and cartilage
• Bone

  • Tissue formed by living cells
• When bones burn, minerals are left
• Bone is living
• Types of bones


  • Compact bone
  • Spongy bone
• Compact bone


  • Outer shell of bones and shaft of limb bones
  • Dense and hard, providing strength for strong support (body weight)
  • Shaft filled with yellow bone marrow that stores lipids
  • High storage of calcium salts
• Spongy bone


  • The heads of limb bones
  • Porous, providing strength with a minimum of additional weight
  • Filled with red bone marrow that produces red blood cells
• Blood vessels and nerves in bone

  • Blood supplies oxygen and nutrients, supports growth and development, removes carbon dioxide and wastes
  • Nerves give sensation of the bones and help with balance
• Cartilage


  • Formed by living cells
  • Softer and more elastic than bones, contains fewer minerals
  • Present at the end of the bone, reduces friction between bones at the joint during movement and absorbs shock
  • Gives shape and support to some structures (not all)
  • Has no blood vessels or nerves
  • Prevents wearing of bones
• Wearing of cartilages exposes pain receptors, stimulating pain
• Osteoporosis


  • Bone material of a person decreases, higher chance of bone fracture
  • Bones become lighter and more porous
  • Lack of calcium and vitamin D
• Weight exercise stimulates increase in bone mass
• Components of the human skeleton

  • Axial skeleton
  • Appendicular skeleton
• Axial skeleton


  • Lies on the central axis
  • Consists of skull, vertebral column, and ribcage
  • Supports and protects internal organs
• Skull


  • Consists of the cranium and facial bones
  • Cranium is made up of 8 bones fused together at joints called sutures, immovable
  • Protects the brain, eyes and ears
  • Orbit protects the eyeball
  • Jaw forms the framework of the mouth and holds teeth
  • Upper jaw fuses with the cranium, immovable
  • Lower jaw forms movable joints with cranium
• For newborns, bones of the skull are not yet fused together to make birthing easier, will fuse together as they grow
• Vertebral column


  • Made up of 33 vertebrae articulated by joints
  • Supports weight of upper body
  • S-shape acts as a spring to absorb shock
  • Protects spinal cord
  • Contains compressible discs of cartilage between vertebrae (intervertebral discs) that allow bending
  • Provides surfaces for muscle attachments
• The vertebrae are linked together by ligaments to form a column, allowing attachment of muscles
• Contraction of skeletal muscles produces the required force to keep the skeleton in position
• Features of the backbone that allow it to bend

  • The backbone is made up of 33 vertebrae which are articulated by joints
  • There are compressible intervertebral cartilage discs between the vertebrae
• Functions of the vertebral column

  • Supports body weight
  • Protects spinal cord
  • Provides surface for muscle attachment
• Ribcage


  • Consists of 12 ribs connected to the sternum and vertebral column
  • Protects lung and heart
  • Helps to bring about breathing movement
• Rib bone is connected to cartilage, then to the sternum or vertebral column
• Appendicular skeleton


  • Lies on both sides of the body
  • Consists of limb bones and girdles for movement
• Limb bones


  • Form the lever system for effective movement
  • Allow movement
• Pectoral girdle (shoulders)


  • Attach the limb bones to the axial skeleton
  • Shoulder blade provides a large surface area for the attachment of muscles to hold the arm
  • Forms the cavity for the shoulder joints
• Pelvic girdle (hips)


  • Attach the limb bones to the axial skeleton
  • Supports and protects the organs of the lower abdomen
  • Forms the cavity for the hip joints
• Functions of the skeleton

  • Support body weight
  • Allow body to stand upright
  • Give shape to body
  • Allow movement
  • Protect organs
  • Produce blood cells
  • Store minerals and lipids
• The skeleton provides support through the action of muscles, without muscles the skeleton would collapse
• Ligaments


  • Tough and elastic, allow a certain degree of flexibility in the movement of bones
  • Fibrous tissue that holds bones together at a joint
  • Holds bone in position and prevents dislocation
  • Forms a capsule to hold bones together
• Cartilage at joints


  • Covers the end surfaces of bones
  • Elastic and smooth, reduces friction between bones during movement
  • Prevents bones from wearing away
  • Absorbs shock
• Fibrous capsule and synovial membrane


  • Fibrous capsule is the tissue enclosing the joint
  • Synovial membrane is under the fibrous capsule, covers the inner surface of the ligament, and secretes synovial fluid into the synovial cavity to lubricate and nourish the cartilage cells
• Less synovial fluid leads to increased friction, wearing of cartilage, and pain
• In the elderly, decreased synovial fluid secretion in the knee joint leads to cartilage wearing and pain when walking
• Types of movable joints


  • Hinge joint
  • Ball-and-socket joint
  • Fixed joint
• Hinge joint


  • Allows movement of bones in one plane only, e.g. elbow and knee
• Ball-and-socket joint


  • Allows movement of bones in many planes, e.g. shoulder and hip
• Fixed joint


  • Prevents movement of skull bones, forming a rigid and complete case to protect the brain
• Skeletal muscles


  • Muscles attached to the skeleton
  • Tissue made up of bundles of muscle fibres bound together by connective tissue
  • Muscle fibre is a muscle cell with many nuclei and mitochondria
  • Striated muscles contain light and dark bands
• Skeletal muscles never completely relax, keeping the muscle ready for immediate contraction and the body in an upright position