Skeletal system

• Invertebrate animals

  • Jellyfish
  • Worms
• Exoskeleton

  • External
  • Found in invertebrates
  • Consists of chitin
  • Advantages: Provides support and protection, place for muscle attachment, prevents body from desiccation
  • Disadvantage: Limits size
• Endoskeleton

  • Internal
  • Consists of bone and cartilage
  • Advantages: Can grow to large size, protects organs, provides support and shape, makes movement possible
  • Disadvantages: vulnerable to dessication and injuries
• Functions of skeleton

  • Movement
  • Protection
  • Support
  • Blood cell formation
• Appendicular skeleton

  • Pectoral girdle
  • Pelvic girdle
  • Lower and upper limbs
• Bone types

  • Compact bone: hard, dense, provides strength and support
  • Spongy bone: softer, lighter, exerts resistance against forces
• Bone marrow

  • Yellow bone marrow: contains fat cells and leukocytes
  • Red bone marrow: produces erythrocytes
• Joints

  • Immovable
  • Semi-movable
  • Freely (synovial) movable
• Structure of synovial joint

  • Covered with hyaline cartilage
  • Enclosed by joint capsule
  • Lined with synovial membrane that secretes synovial fluid
• Types of synovial joints

  • Ball and socket - Allows movement and rotation in all directions
  • Hinge - Allows movement in 1 plane only
  • Pivot - 1 bone rotates around another
  • Gliding - 1 bones flat articular surface slides on another
• Antagonistic muscles

  When one contracts, the other relaxes
• Rickets

  Bones weaken, shortage of vitamin D
• Osteoporosis

  Decrease in bone density, shortage of calcium, pain
• Arthritis

  Causes severe pain and loss of movement, inflammation in joints
• Osteoarthritis

  Cartilage that forms part of a joint ages and disintegrates
• Rheumatoid arthritis

  Synovial membranes in joints thicken and produce too much synovial fluid, autoimmune disease
• Hydrostatic skeleton

  . Provides support coz the fluid is kept under pressure

  . Doesn't need specialised support system

  . Flexible

  . Rapid healing

  . Can't walk

  . Limits size

  . Found in moist environments
• Skeletal muscles

  Attached to skeleton, allows movement by contraction and relaxation
• Functions of skull

  Protects brain and sense organs
• Functions of rib cage

  Plays a role in breathing and protection
• Functions of vertebral column

  •protection

  •support

  •attachment for muscles

  •flexibility
• Axial skeleton

  • skull

  •vertebral column

  •rib cage