Cartilage PDF

Cartilage Dr Fraser Philp Intended learning outcomes Cartilage Identify and describe the different types of cartilage indicating their locations Describe the structure and function of cartilage Describe introductory processes related to the growth and repair of cartilage Cartilage Consi...

Cartilage Dr Fraser Philp Intended learning outcomes Cartilage Identify and describe the different types of cartilage indicating their locations Describe the structure and function of cartilage Describe introductory processes related to the growth and repair of cartilage Cartilage Consists of a dense network of collagen fibres firmly embedded in chondroitin sulfate. Chondroitin sulfate is Loading… a gel like component of the ground substance Can endure considerably more stress than loose and dense connective tissue.  High resistance to tensile, compressive and shearing forces Cartilage - Roles support soft tissues; provide a smooth, gliding surface for bone articulations at joints; enable the development and growth of long bones. Classifying cartilage Skeletal connective tissue Bone Cartilage Loading… Hyaline Articular cartilage Fibrocartilage Elastic Features of cartilage types Features Hyaline cartilage Fibrocartilage Elastic cartilage Collagen Thin, fine collagen fibres Thicker bundles of collagen fibres Threadlike network of elastic fibres within extracellular matrix Location of cells Prominent chondrocytes are found in Chondrocytes scattered among thicker chondrocytes are located within a lacunae bundles of collagen fibres threadlike network of elastic fibres within extracellular matrix Presence of Most hyaline cartilage surrounded by Lacks perichondrium Perichondrium present perichondrium perichondrium – except for articular cartilage in joints and epiphyseal plates Characteristics Most abundant, provides flexibility and Strong and rigid Gives support and maintains shape support, at joints reduces friction and (elasticity) absorbs shocks Relative strength Weakest of the three Strongest of the three types of cartilage Second strongest Cartilage Supporting / specialised connective tissue type Relatively avascular –penetrated by vascular channels from surrounding tissues (perichondral blood vessels) – secretes an antiangiogenesis  No nerve supply Components of cartilage - Cells Chondroblasts – immature cells – produce extracellular matrix Chondrocytes – mature cells – maintain extracellular matrix Cells either singly or in groups occupying small spaces called G lacunae in the matrix, which conform to the cell shape Components of cartilage – Fibres and ground substance Fibres Meshwork of Collagen (mainly strong Type 2 fibres) are embedded within the ground substance The meshwork arrangement of the Collagen gives strength and also helps to hold the gel-like ground substance in place Ground substance Proteoglycan Found within the Ground Substance Complex macromolecules = Core protein attached to Loading… Glycosaminoglycans (GAG’s) Proteoglycans bind with water = ‘molecular sponge, allows  compressibility + shock absorbency Loading articular cartilage Onloading - Fluid pressure rises immediately - Cartilage gradually deforms - Water moves out Like squeezing a wet sponge in After removal of load - Fluid pressure drops - Cartilage gradually water returns to normal shape Water moves back in  ‘Collagen Arcade’ of cartilage Superficial horizontal collagen fibres Intermediate layer = collagen arcade Deep vertical collagen fibres Nutrition Articular cartilage receives its nutrition by diffusion from underlying subchondral bone synovial membrane at the periphery of the cartilage synovial fluid in the joint Perichondrium A layer of dense connective tissue that surrounds the perimeter of most cartilage surfaces Articular cartilage (Fibrocartilage & some Hyaline cartilage) is not covered by perichondrium Perichondrium comprised 2 layers: Healing & repair Cartilage is a relatively inactive tissue that grows slowly Cartilage has low ability to regenerate and probably only does so in the young (given it’s avascular nature) In adults damage to cartilage results in formation of fibrous scar tissue - which does not have the same properties as Hyaline cartilage  Healing & repair Growth of cartilage follows two basic patterns 1. Interstitial growth Occurs while the cartilage is young and pliable during childhood and adolescence 2. Appositional Growth Starts later than appositional growth and continues through  adolescence Healing & repair Interstitial growth - rapid size increase due to the division of chondrocytes and continuous deposition of extracellular matrix expands like rising bread as chondrocytes are pushed away from each other as they synthesise the new matrix Appositional Growth - Growth on the outer surface of the tissue Cells in the inner cellular layer of the perichondrium differentiate into chondroblasts Differentiated cells surround themselves with extracellular matrix and become chondrocytes Matrix accumulates beneath the perichondrium on the outer surface of the of the cartilage causing it to increase width Can you now Connective Tissue Describe the classification of different types of connective tissue Describe the structure and function of different types of connective tissue indicating their locations Describe introductory processes related to the growth and repair of cartilage Further reading Principles of anatomy and physiology / Gerard J. Tortora, Bryan Derrickson – available electronically UoL library Page 122 to 134 Nice pictures form 125 to 134 for tissue types