Biology

• Skeleton


  The framework of the body which gives support and shape to an Organism
• Types of Skeleton


  • Hydrostatic skeleton
  • Exoskeleton
  • Endoskeleton
• Hydrostatic Skeleton


  Formed by fluid excreted to fill the spaces in the body, possessed by soft bodied animals. The fluid presses against the muscular body wall, causing muscles to contract, exerting a force against the fluid. This helps to maintain the shape and form of the animal
• Organisms with Hydrostatic Skeleton

  • Earth worm
  • Tape worm
  • Round worm
• Exoskeleton


  The type of skeleton that is found outside or external part of the body of some animals. Most invertebrates do possess cuticle which is composed of chitin strengthened by deposits of protein and mineral especially CaCO3. Calcerous exo skeletons is common in aquatic crustaceans like crabs and prawns.
• Organisms with Exoskeleton


  • Can only grow by a process called Moulting or ecdysis
• Endoskeleton


  The type of skeleton which is found inside the body of animals. Endoskeleton exists in bony or cartilaginous skeleton of fishes, toad, lizards, birds and mammals. Endoskeleton in vertebrates is made of cartilage and bones.
• Biological Significance Of Skeleton

  • Protection
  • Movement
  • Support
  • Shape
  • Attachment
  • Breathing
  • Mineral Reserve
  • Red blood cells
• Forms and Components of Skeleton

  • Fluid (in Hydrostatic skeleton)
  • Cuticles
  • Bones
  • Cartilages
• Cuticles


  Composed of a protein called Chitin and a thin water proof layer of wax
• Bones


  A tissue and a major component of vertebral skeleton. It consists of living cells (osteocytes), protein fibres (collages) and minerals mainly CaCO3 and CaPO4. Bone is more rigid and stronger than cartilage and bone cells replace cartilage as the young vertebrate grows by a process known as Ossification. A bone usually consists of a hard outer layer (shaft) and a spongy or hollow cavity filled with bone marrow.
• Cartilages


  A tissue found in the skeleton of complex vertebrates. It consist of living cells (Choridroblasts), carbohydrates and protein fibres. It is tough and flexible tissue that has great tensile strength. It acts as a shock absorber, cushioning the effect of bones moving against bones during movement
• Types of Cartilages


  • Hyaline cartilage
  • Fibrio - cartilage
  • Elastic cartilage
• Bone


  Made up of living cells
• Cartilage


  Made up of mainly living cells
• Bone


  Not flexible
• Cartilage


  Very flexible both in adults and young ones
• Bone


  Made up of hard substance
• Cartilage


  Made up of soft substance
• Bone


  Can never be replaced by a cartilage
• Cartilage


  Can easily be replaced by bone
• Bone


  Made up of mainly of mineral salts
• Cartilage


  Not made up of mainly mineral salts
• Mammalian Skeleton


  Two major parts: Axial and Appendicular skeleton
• Axial Skeleton


  • Skull
  • Vertebral column
  • Ribs
  • Sternum
• Appendicular Skeleton


  • Limb girdle (pectoral and pelvic girdles)
  • Limbs (forelimbs & hind limbs)
• Skull


  • Contains cranium, facial bones, and jaws
  • Cranium protects the brain
  • Facial bones carry the nose, eyes and upper cheek
• Vertebral Column


  • Made up of vertebrae
  • Vertebrae form a hollow tube through which the spinal cord passes
  • Five types of vertebrae: Cervical, thoracic, lumber, sacral and caudal
• Typical Vertebra


  • Centrum
  • Neural arch
  • Neural canal
  • Neural spine
  • Two transverse processes
  • Facets for articulation (Zygapophyses)
• Ribs


  • 12 pairs
  • Lie in the wall of the thoracic vertebrae
  • Attached dorsally to the rib curve and ventrally to the sternum
  • Form the bony cage that protects the heart and lungs
  • Articulate with thoracic vertebrae via capitulum and tuberculum
• Pectoral Girdle


  • Made of two halves
  • Each half has a scapula, coracoids, and clavicle
  • Glenoid cavity where the head of the humerus fits
• Pelvic Girdle


  • Made of two halves fused at the pubis symphysis
  • Each half is an innominate bone composed of ilium, ischium, and pubis
  • Obturator foramen between pubis and ischium
  • Acetabulum where the head of the femur fits
• Forelimb


  • Humerus, radius, ulna, carpals, metacarpals, phalanges
• Hindlimb


  • Femur, tibia, fibula, tarsals, metatarsals, phalanges
• Forelimbs and hindlimbs are built on the same basic pentadactyl pattern
• Food


  Any substance which when absorbed to the body cells yields energy, material for growth, repairs of damaged tissues and regulation of body processes without harming the living organism
• All animals depend on plants directly or indirectly for their food
• Food classes


  • Carbohydrates
  • Fats and oil
  • Protein
  • Mineral salts
  • Vitamins
  • Water
• Carbohydrates


  Made up of: carbon, oxygen and hydrogen e.g. sugars, starch, cellulose, glycogen. For energy
• Fats and oils


  Made up of: carbon, oxygen, hydrogen. e.g. fatty acids and glycerol. Produce more energy than carbohydrates, insulation of the body; part of cell membrane