Functions:
◘ Support soft tissues (nose, ear, trachea).
◘ Shock-absorbing and sliding areas for joints, facilitate bone movements.
◘ Essential for the development and growth of long bones.
Cartilage composition
CellsChondrocytes: located within matrix; lacunae
Chondroblasts: located at periphery; secrete extracellular matrix
Fibers Collagen and elastic fibersGround substanceRich in glycosaminoglycans and proteoglycans
Cartilage composition
Perichondrium is a layer of dense irregular connective tissue.
It is essential for the growth and maintenance of cartilage.
Perichondrium
More Features of Cartilage
Avascular; Nutrients diffusion from perichondrium or syn
ovial fluid; No innervation; No lymphatic vessels; Chondrocytes have low metabolic activity
Classification:
Hyaline cartilage: most common, much type II most common, much type II collagencollagenElastic cartilage: elastic fiberselastic fibers
Fibrocatilage: dense network of type I collagendense network of type I collagen
Properties of extracellular matrix
Hyaline Cartilage
Blue-white and translucent distribution : Joint surfaces, nose, larynx, trachea, bronchi,
ends of ribs adjacent to sternum
Structure
Cells: chondrocytes
Extracellular matrixfiberground substance
PerichondriumPerichondrium is a layer of dense irregular connective tissue.
It is essential for the growth and maintenance of cartilage.
Found around all HC except joint HC
Rich in fibroblasts, chondroblasts, blood vessels,
and nerves.
1. Chondrocyte
(1) In hyaline cartilage, yaline cartilage, chondrocytes are distribchondrocytes are distributed either singly or in uted either singly or in clustercluster
lacunae :isogenous nest : chondrocytes arranged in pair or group of four or six
(2) chondrocytes are specialized cells that prochondrocytes are specialized cells that produce and maintain the extracellular matrixduce and maintain the extracellular matrix
2. Matrix
(1) Hyaline cartilage matrix is produced by chonHyaline cartilage matrix is produced by chondrocytes and contains three major classes of modrocytes and contains three major classes of molecules:lecules:
①Collagen molecules
②Proteoglycans
③Nocollagenous proteins
fiber—— mainly type collage fiber Ⅱ
ground substance
(2) Grounds substance componenGrounds substance components of hyaline cartilage matrix are ts of hyaline cartilage matrix are not distributed uniformlynot distributed uniformly
Capsusle/territorial matrix (TM) :matrix surrounding each chondrocyte
Interterritorial matrix (IM) :matrix between the territorial matrix
Elastic CartilageElastic Cartilage
• Auricle of ear, external auditory canal, epigAuricle of ear, external auditory canal, epiglottislottis
• Similar to HC, many elastic fibers in the mSimilar to HC, many elastic fibers in the matrixatrix
• PerichondriumPerichondrium
FibrocartilageFibrocartilage
• Found in Intervetebral disks, tendon and Found in Intervetebral disks, tendon and ligament attachment to bone, symphysiligament attachment to bone, symphysis pubiss pubis
• Combination of HC and dense regular cCombination of HC and dense regular connective tissueonnective tissue
• Chondrocytes often in rows or groupsChondrocytes often in rows or groups
• Matrix acidophilic due to high collagenMatrix acidophilic due to high collagen
• No perichondriumNo perichondrium
summary
• Cartilage is a semi-rigid form of connective tissue
• 3 types of cartilage• structure of hyaline cartilage
Overview of bone
· Bone is a specialized form of connective tissue.
Cells
Extracellular matrix: mineralization
· Functions of bone:
Support: Provides attachment for tendoProvides attachment for tendons of skeletal musclesns of skeletal musclesProtection: Protects internal organsProtects internal organs
Storage: calcium ,phosphate
1. Matrix· Organic matter
type I Collagen: 90%
Ground substance: 10%
· Inorganic matter ( bone mineral )The inorganic matter is calcium phosphate in the form of hydroxyapatite crystle [Ca10(PO4)6(OH)2]
Structure of bone
endosteum : lined on internal surfaceperiosteum : lined on external surface
-- Resting cell that can transform into osteoblast.
-- Found on the external and internal surfaces of bones.
-- Only bone cells that undergoes cell division, daughter cells becomes osteoblasts
A. osteoprogenitor cell
C. osteocyte-- mature cell and is enclosed by bone matrix
-- osteocytes are found in matrix.
Lacuna
Canaliculi
D. osteoclast
-- responsible for bone resorption.
-- rest directly on bone where resorption is taking place.
Compact bone--has no cavities.
--forms the outside of the bone.
Spongy bone
--has numerous interconnecting cavities.
--forms the interior of the bone.
Compact Bone
Functional Unit is the Functional Unit is the OOsteonsteon or or Haversian SysHaversian Systemtem—concentric rings —concentric rings of lamellae around a Ceof lamellae around a Central Canal, with connentral Canal, with connecting Peripheral Canalscting Peripheral Canals
1.osteon
2.outer circumferential lamellae
3.inner circumferential lamellae
4.interstitial lamellae
Compact Bone
HistogenesisHistogenesis
Intramembranous ossification: flat boneIntramembranous ossification: flat bone
Endochondral ossification: short and long Endochondral ossification: short and long bonebone
Summary
· Matrix:
organic matter, inorganic matter and a little water
· Cells : osteoprogenitor cell, osteoblast, osteocyte and osteoclast
· Structure of long bonesperiosteum and endosteum, epiphysis, diaphysis
ossification