1. Structure of Bone & Cartilage Sanjaya Adikari Department of Anatomy

2. Connective tissue Cells Cells producing extracellular material Other cells (immune cells, fat cells) Extracellular material Ground substance – matrix of organic material Fibres

3. Connective tissues

4. Ground substance Glycosaminoglycan Hyaluronic acid with protein Barrier to the spread of micro-organisms Soluble proteins & glycoproteins Tissue fluid/extracellular fluid is loosely bound to the ground substance

5. Cartilage A semi-rigid tissue Variable amounts of collagen and elastic fibres Three types – Hyaline cartilage (consist of collagen fires) – Elastic cartilage (consist of collagen and lot of elastic fires) – Fibrocartilage

6. Cartilage Nerves Blood vessels Perichondrium cells diffusion

7. Chondroblasts Lacuna/ space Chondrocytes

8. Cartilage… Grow by – Interstitial growth (chondrocytes dividing & forming clusters) – Appositional growth (chondroblasts differentiating into chondrocytes) Adults have a limited distribution of cartilage Newborns have more extensive distribution

9. Hyaline Cartilage Most common type Found in, nasal septum, larynx, tracheal rings, costal cartilages and articular surfaces of sinovial joints Newborns have more extensive distribution since they act as templates for most of the long bones

10. Elastic Cartilage Found in, external ear, external auditory canal, epiglottis and wall of Eustachian tubes. Differ from hyaline cartilage by having numerous elastic cartilage bundles in the matrix

11. Hyaline cartilage Elastic cartilage

12. Fibrocartilage Found in, intervetebral discs, some articular cartilages and pubic symphysis. Features appear intermediate between cartilage and dense fibrous connective tissue There are alternating layers of hyaline like cartilage and thick layers of collagen fibres.

13. Fibrocartilage

14. Bone A specialized connective tissue Extracellular components are mineralized - rigid Supporting and protective functions Function as a calcium ion store Growth and resorption throughout life - dynamic

15. Bone…… Cells – – Osteoblasts: secrete extracellular matrix (osteoid) – Osteocytes: maintain bone matrix – Osteoclasts: remove bone matrix Extracellular matrix – – glycoprotein ground substance, collagen fibres, mineral component by calcium hydroxyapatite

16. epiphysis diaphysis periosteum endosteum cavity (contains yellow marrow) growth plate red marrow

18. Microscopic structure Haversian canals with vessels and nerves They are arranged parallel to the long axis Connected by canals running across, called Bone cells are arranged around Haversian canals in circles The cells lay down bone in circles called lamellae

19. Microscopic structure Cortical bone Volkmann’s canal Haversian system

20. Canaliculi

21. Cortical bone Interstitial system (old Hav Sys) New Haversian system

23. Bone Woven bone Lamellar bone Compact bone Cancellous bone immature bone. Random organization of fibrous elements mature bone forms walls of the shaft & a thin layer around the epiphysis of long bones found in the epiphysis or around the medullary cavity

24. Resorption Apositional growth Osteoclast Osteoblast Periosteum PTH Reduced calcium ions Increased calcium ions Calcitonin _ + + +