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29 Cards in this Set
- Front
- Back
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Cartilage and Bone |
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Tissue Types |
Epithelium
Connective tissue: (loose & dense), cartilage, bone, blood Muscle tissue Nervous tissue |
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Tissue Origins #1 |
Common embryonic origin: mesenchyme Cellular descendants: fibroblast, fibrocyte, chondroblast, chondrocyte, osteoblast, osteocyte, hematopoietic stem cell, blood cells (and macrophages) Class of connective tissue resulting: connective tissue proper, cartilage, osseous (bone), blood |
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Tissue Origins #2 |
Subclasses: Loose connective tissue (areolar, adipose, reticular), Dense connective tissue (regular, irregular, elastic), Hyaline cartilage, Fibrocartilage, Elastic cartilage, Compact bone, Spongy bone (cancellous) |
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Cartilage Definition |
Firm, flexible connective tissue found in various forms in the larynx and respiratory tract, in structures such as the external ear, and in the articulating surfaces of joint. It is more widespread in the infant skeleton, being replaced by bone during growth |
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Cartilage #1 |
Specialised cells called chondrocytes Abundant extracellular matrix: fibers:collagen and elastin (fibro and elastic only), Jellylike ground substance of complex sugar molecules (proteoglycan), 60-80% water (reponsible for the resilience), no nerves or blood/lymph vessels |
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Cartilage #2 |
Hyaline cartilage: flexible and resilient Elastic cartilage: highly bendable Fibrocartilage: resists compression and tension |
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Hyaline Cartilage Description |
Amorphour but firm matrix, collagen fibers form an imperceptible network, chondroblasts produce the matrix and when mature chondrocytes lie in lacunae Only collagen fibers |
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Hyaline Cartilage Function |
Supports and reinforces, has resilient cushioning properties, resists compressive stress |
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Hyaline Cartilage Location |
Forms most of the embryonic skeleton, covers the ends of long bones in joint cavities, forms costal cartilages of the ribs, cartilages of the nose, trachea and larynx |
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Elastic Cartilage |
Similar to hyaline cartilage with more elastic fibers in matrix Maintains the shape of a structure while allowing great flexibility Supports the external ear (pinna), epoglottis |
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Fibrocratilage |
Matrix similar to but less firm than that in hyaline cartilage, thick collagen fibers predominate Tensile strength with the ability to absorb compressive shock Intervertebral discs, pubic symphysis, discs of knee joints |
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Osteoarthritis |
Hyaline cartilage failure leads to degenerate joint disease Unable to dissapate mechanical forces & protects underlying bone Most common form is osteoarthritis (OA) Up to 12 million people suffer from OA in the UK alone Causative factors unclear |
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Articular Cartilage (Hyaline) |
Matrix predominantly collagen Type II (65% dry weight) and glycosaminoglycans (GAGs, 25% dry weight) 5-10% cells - chondrocytes Chondrocytes 100% responsible for matrix turnover |
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Molecular Structure |
Collagen Matrix, Aggrecan Monomer, Hyaluronan Aggrecan Monomer: core protein, chondroitin sulphate chains, keratan sulphate chains, link protein Fixed negative charges (sulphate), Cations (Na+), Water |
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Molecular Form/Function |
Highly fixed negative charge
Increases cation concentration Increases solution osmolarity Water follows by osmosis GAG molecules effectively swell Swelling resisted by collagen network |
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String & Balloon Model |
Collagen fibres, glyocosaminoglycan Collagen fibres restrict GAG swelling Ion concentration not equilibriated Resting osmolarity -380mOsm (synovial fluid 280mOsm) |
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Practical Demonstration |
Papain stimulates release of GAG degredative enzymes from chondrocytes Loss of GAGs (balloons in string and balloon model) |
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Overview of Cartilage Degeneration #1 |
Normal - Matrix synthesis = Matrix breakdown Osteoarthritis - Matrix synthesis < Matrix breakdown |
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Overview of Cartilage Degeneration #2 |
Matrix metalloproteases increase (collagen digesting) Collagen fibres broken down (string snipped) GAG hydration not resisted - tissue swells Loses functionality |
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Bone Definition |
Any of the pieces of hard whitish tissue making up the skeleton in humans and other vertebrates |
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Bone Matrix |
70% inorganic salts and 30% organic matrix Organic component: 95% collagen Type I, 5% proteoglycan + non-collagen molecules Inorganic mainly Ca2+ and PO4- as hydroxyapatite crystals fill gap between collagen fibres |
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Bone Types |
Cancellous (Trabeculla, Spongy) Cortical (compact bone) Medullary cavity |
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Cortical (compact) bone #1 |
Resembles a solid layer of hard bone External layer of all bones Resists stress from weight and movement Arranged in unit called osteons |
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Cortical (compact) bone #2 |
Interstitial lamellae, Circumderential, Lymphatic vessels, Central canal, Perforating canal, Periosteum, Osteum: concentric lamellae, blood vessels, lymphatic vessels |
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Cancellous (Trabecula, spongy) bone |
Branching bone projects from internal surface (trabecular) Fills marrow cavity spaces Trabecular are only a few layers thick Typically no osteons |
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Bone Cells #1 |
Osteogenic cell (develops into an osteoblast), Osteoblast (forms bone matrix), Osteocyte (maintains bone tissue), Osteoclast (functions in resorption the breakdown of bone matrix) |
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Bone Cells #2 |
Osteocytes (sensors), Dendrites Damaged zone: osteoclasts, osteoblasts |
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Bone Remodelling |
Quiescent bone surface covered by lining cells Osteoclasts on the bone surface resorbing old bone Osteoblasts appearing at the resorption site Osteoblasts filling the resorption cavity with osteoid Osteoid becoming mineralised |
