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Cartilage and Bone (PowerPoint)

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					CARTILAGE &
BONE
 Intoduction: Skeletal System
• The hard structure that provides a frame for
  supporting the soft tissues and protecting the
  internal organs.
• Skeletal system includes
   – Bones
   – Cartilages
   – Ligaments
   – Other connective tissues that stabilize or
     connect the bones (eg tendon)
 Functions of skeletal system
• Support the body weight.
   – Bones provide a framework for attachment of soft
     tissues
• Storage of minerals and lipids.
   – Calsium, phosphate ions, lipids
• Blood cell production.
   – (RBC, WBC, platelets)
• Protection of soft tissues and organ.
   – Ribs the heart, lungs
• Leverage
   – Bones acting as levers for muscle movements.
 Glossary
• Osteology
   – Greek osteon = bone, and logy = a field of study
   – Osteology is the scientific study of bones that deals
     with the structure of bones, the process of
     ossification.
• Arthrology
   – The study of the structure and function of joints.
   – Joint - where the ends of two or more bones meet.
• Cartilage
   – A tough, rubbery, fibrous, dense connective tissue
     found in various parts of the body, such as the
     joints, outer ear, and larynx.
   – Chondral - pertaining to cartilage.
    Bones
• Also called osseous tissue, (Latin: "os")
• Is a type of hard endoskeletal connective tissue
• Provide the body structure,
• Facilitate movement(in conjunction with muscles).
• Protect the internal organs.
• Involved with cell formation, calcium metabolism, and
  mineral storage.
• The adult human body has 206 of them.
• Bone has a different composition than cartilage, and
  both are derived from mesoderm
 Divisions of the Skeleton
• The human skeleton is divided into two
  distinct parts
• The axial skeleton
   – consists of bones that form the axis of the
     body and support and protect the organs of
     the head, neck, and trunk.
     •   The Skull
     •   The Sternum
     •   The Ribs
     •   The Vertebral Column
 (cont.)
• The appendicular skeleton
   – is composed of bones that anchor the
     appendages to the axial skeleton.
     •   The Upper Extremities
     •   The Lower Extremities
     •   The Shoulder Girdle
     •   The Pelvic Girdle (the sacrum and coccyx are
         considered part of the vertebral column)
The axial skeleton &
The appendicular
skeleton
  Bone Shapes
• Long bones
    – Longer than they are wide and work as levers. Eg bones of
      the upper and lower extremities (humerus, tibia, femur, ulna,
      metacarpals, etc.)
• Short bones
    – Short, cube-shaped, and found in the wrists and ankles.
• Flat bones
    – Have broad surfaces for protection of organs and attachment
      of muscles (eg ribs, cranial bones, bones of shoulder girdle).
• Irregular bones
    – All others that do not fall into the previous categories. They
      have varied shapes, sizes, and surfaces features and include
      the bones of the vertebrae and a few in the skull.
• Sesamoid bones
    – Small, flat and shaped like a sesame seed.
 Structure of long bone
• Proximal and distal epiphyses (singular is epiphysis)
  which are the dilated “ends” of the bone.
• Diaphysis - the tubular shaft of the bone.
• Proximal and distal metaphyses – the area between
  each epiphysis and the diaphysis.
   – In a child’s, metaphysis is called an epiphyseal
     plate and consists of growing hyaline cartilage.
   – In an adult, the metaphyses are called epiphyseal
     lines and consist of osseous connective tissue.
Typical structure of a long bone
 Structures of long bone
• Periosteum - connective tissue.
• Proximal and distal articular cartilages –
  hyaline cartilage
• Spongy bone (aka cancellous or trabecular
  bone)
• Compact bone – forms the tubular
  diaphysis.
• Medullary cavity – the space within the
  diaphysis.
• Endosteum – connective tissue.
• Nutrient artery and nutrient foramen.
Structures of long bone
 Cartilage & Bone
• Make up the skeletal system
• A type of connective tissue
  – Have cells, fibers & ground substances
     (amorphous)
  – Ground substance = substances in
     between the cells
• Can withstand high pressure/force
• Supporting & protecting soft tissues
 Cartilage (chondral)
• Cartilage is a structural tissue like bone.
• A semi-rigid tissue & pressure-tolerant (unlike bone).
• It can be found on the ends of bone.
   – e.g. hyaline cartilage.
• Has an amorphous cellular structure.
   – Allows for diffusion of nutrients to the cartilage
      cells.
• Consists of
   – Cartilage cells (chondrocytes), and
   – A dense network of collagen fibers and elastic
      fibers embedded in chondroitin sulfate (a gel-like
      component of ground substance).
 (cont.)
• Cartilage undergoes both
   – Interstitial (growth within the tissue) and
   – Appositional (growth at surfaces) growth.
• Cartilage has no blood vessels, nerves or lymphatic
  vessels.
   – Receives nutrient from nearby blood vessels of
     connective tissue or from body fluid (eg sinovial
     fluid).
• 3 types (based on fibers & matrix):
   – Hyaline cartilage
   – Elastic cartilage
   – Fibrocartilage
    Function of cartilage
•   Support – skeleton of foetus.
•   Movement – articular cartilage.
•   Growth & development of bones.
•   Healing – fracture
 Perichondrium
• Layer of dense irregular connective tissue.
• Seen as 2 layers:
   – Outer layer –  collagen fiber.
   – Inner layer –  chondrogenic cells (from
     mesenchymal).
• Function:
   – Development of cartilage.
   – Maintainance of cartilage.
   – Fracture healing – fibroblast & mesenchymal cells.
• Covers most of the cartilage except for the articular
  surface.
 Chondrocyte
• Cells of mature cartilage.
• Oval shape (immatured), spherical (matured)
• Can be found in cartilage matrix inside a
  lacuna (space within cartilage tissue)
   – Peripheral lining: parallel to the
     perichondrium
   – Internal lining: groups within lacunae
• High mitotic activities.
Chondrocytes
 Hyaline cartilage
• The most abundant cartilage in the body.
• Consists of
   – A bluish-white, shiny ground substance
   – Fine collagen fiber (type II).
   – Many chondrocytes.
• Ground substance is made of proteoglican
  (polisacharide) which is rich in sulfate
   – Sulphate gives the dark blue appearence arround
     the lacuna through H&E staining (territorial matrix).
• Perichondrium is present.
• Location: long bones (articular surfaces), nasal
  septum, larynx, bronchus, trachea, fetal skeleton.
Hyaline cartilage
           Hyaline Cartilage. H&E.




Note the ovoid chondrocytes residing within their
lacunae, a well-stained intercellular matrix.
    Hyaline Cartilage, Larynx. H&E. 400x.




Note several chondrocytes residing within their lacunae.
The interterritorial matrix and the pericellular matrix
that immediately surrounds the lacunae.
 Elastic cartilage
• Looks a lot like hyaline cartilage.
• Consits of chondrocytes located in a
  threadlike network of elastic fibers within the
  matrix.
• Provides strength and elasticity to maintain
  the shape of certain structures.
• Yellowish in color due to the elastic fibers.
• Perichondrium is present.
• Location: epiglottis, external ear, auditory
  tube.
Elastic cartilage
  Elastic Cartilage Epiglottis. H&E. 100x.




Note presence of elastic fibers in the ground substance.
 Elastic Cartilage Epiglottis. H&E. 400x.




Note the presence of elastic fibers in the cartilage
matrix and the chondrocytes within their lacunae.
 Fibrocartilage
• Main feature: combination of hyline cartilage
  and dense connective tissue.
• Consists of chondrocytes scattered among
  bundles of collagen fibers within the matrix.
   – Chondrocytes are arranged in column.
• Collagen fibers are made of type I collagen.
• Amorphous ground substance is limited
  arround the lacuna.
• Lacks a perichondrium.
• Location: intervetebral disc, some ligaments,
  symphisis pubis.
Fibrocartilage
Fibrocartilage. H&E.
 Cartilage growth
• Appositional growth (outside)
   – Chondrogenic cells (from perichondrium)
     differentiate into chondroblasts
   – Chondroblasts synthesis the cartilage
     matrix and turn into chondrocytes.
• Intestitional growth (inside)
   – Mitosis of chondrocytes occurs to form new
     cartilage cells (chondroblasts).
   – Chondroblasts produce fibers and ground
     substances (cartilage matrix).
    Bone (oseus)
• Organ composed of different connective tissues:
   – Bone/oseus tissue.
   – Periosteum & endosteum.
   – Bone marrow.
• Classification according to organization of cells & matrix
   – Spongy bone (with cavity) – canselus bone.
   – Compact bone (without cavity) – lamellated bone.
• Consists of
   – Bone cells – osteoblasts, osteocytes, osteoclasts &
     osteoprogenitor.
   – Matrix (fibers and ground substance).
   – Periosteum & endosteum.
Bone. H&E. 100x.
 Function of bone
• Supports soft tissue
• Protects delicate structure – cranium protect
  the brain
• Works with skeletal muscle to generate
  movement
• Stores mineral – calcium & phosphorus
• Produces blood cells – bone marrow.
   – Eg erythrocyte, leukocyte (neutrophil,
     lymphocyte)
Type of bone cells
 Osteoprogenitor
• Osteogenic cells.
• undergo cell division and develop into
  osteoblasts.
 Osteoblast
• Produces matrix of bones.
   – Bone building cells.
   – Synthesize collagen fibers & organic
     component
   – Initiate calcification.
• Surround themselves with matrix and become
  osteocytes.
• Contains abundant of alkaline phosphatase
 Osteocyte
• Mature bone cells
• Maintain bone tissue
   – Exchange of nutrients and wastes with
     blood
• Do not undergo cell division
• Usually found in lacunae
• Without osteocyte structure of bone tissue
  become porous (osteoporosis)
Bone Cells. Unstain. 20x.
 Osteoclast
• Huge cells ~100um
• Derived from fusion as many as 50
  monocytes.
   – Multinuclei
• Concentrated in the endosteum.
• Mobile with phagocytic activities.
• Secrete lysosomal enzyme & acid.
   – Digest protein & mineral in bone matrix
     (resorption)
• Found in lacuna of Howship.
Osteoclast
 Bone matrix
• The matrix contains
   – Water - 25%
   – Collagen fibers - 25%
   – Crystallized mineral salts (hydroxyapatite) – 50%
• Formed from inorganic & organic substance.
   – Inorganic (70%)
      • Calsium carbonate & kalsium phosphate (hydroxyapatite
        crystal), sitrat, Mg, K, Na, Fl, Cl.
      • Provides compresive strength
   – Organic (30%)
      • Made up of type I collagen fibers & amorphous
        substance.
      • Provides tensile strength (flexsible)
 Periosteum & Endosteum
• Dense connective tissue on bone surfaces
   – Periosteum – external
      • Fibrous layer
      • Cellular layer (contain osteoprogenitor cells)
   – Endosteum – internal (very thin)
      • Inside the trabeculae
• Contains osteogenic cells – fibroblasts
• Blood vessels, lymphatic vessels, and nerves from
  periosteum penetrate the compact bone through
  tranverse perforating canal (Volkman canal).
• Place for tendon, muscle & ligament attachment.
• Not present on the articular surfaces.
 Compact bone
• Bone tissue without cavities.
• Arranged in units called osteon, Harvesian system.
   – Lamellae + Harversian canal = Harversian system.
• Blood vessels, lymphatic vessels, and nerves from the
  periosteum penetrate the compact bone through
  Volkmann’s canal (perforating canal).
   – Vessels and nerves from this canal connect with
     those of the medullary cavity, periosteum & central
     canal.
• Harvesian canals run longitudinally through the bone
  surrounded by concentric lamellae.
 (cont)
• Harversian canal (central canal) - contains
  blood vessel, nerves, and loose connective
  tissue.
• Lamellae – parallel consentric rings of hard
  calcified matrix.
• Osteocyte can be found in between the
  lamellae.
• Osteocyte communicte with each other
  through a structure call canaliculi.
Ground bone. Unstain.
 Arrangement of Harvers
 System
• Lamella arrangement in the diaphysis
   – Harversian lamellae
   – Intermediate/interstitial lamellae
   – Outer circumferential lamellae
   – Inner circumferential lamellae
Lamellae
of bone
 Spongy bone
• Also called trabecular or canselus bone.
   – Contains trebekulae – an irregular
     latticework of thin columns of bones.
   – Spaces between trabeculae contain bone
     marrow (medullary cavity).
• Osteocytes lie in lacunae within each
  trabeculae.
   – Receive nutrient directly from circulating
     blood vessels in the medullary cavities.
• Does not contain osteon (Harvers system).
• Found in the epiphysis of long bones.
Spongy bone
Tulang spongiosa
Bone marrow
 Bone formation - ossification
• Started ~ second month intrauterus
• 2 types of ossification
   – Intramembranous ossification
     • Bones formed directly from mesenchymal tissue
       (osteoprogenitor cells).
     • Occurs mostly in flat bones (cranium, mandible)
  – Endochondral ossification
     • Bones developed from hyaline cartilage.
     • Occurs mostly in long bones (femur, humerus)
Osifikasi intramembran
Bone formation
Endochondral ossification
 Growth of bone
• Types of growth
   – Horizontal
     • New chondral cells produced from mitosis at
       both sides epiphisial plate, cells in the diaphisys
       side died  ossification.
     • Stop at the age of 18 (Female), 20 (Male).
  – Circumferential
     • Osseus tissue in bone marrow cavity died.
     • New osteoblasts from periosteum form into
       osteocytes  ossification.
• Ends of growth differs according to
  ossification centres.
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