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Chapter 2 - Biological Tissue

Chapter 2 - Biological Tissue. Each type of tissue has a specialized function and a distinctive organization. Types of Tissue. Tissue is classified as one of four types: Epithelial Nervous Muscle Connective (Bone, tendon, ligaments, cartilage). Types of Tissue:Epithelial. Lining tissue

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Chapter 2 - Biological Tissue

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  1. Chapter 2 - Biological Tissue Each type of tissue has a specialized function and a distinctive organization

  2. Types of Tissue Tissue is classified as one of four types: • Epithelial • Nervous • Muscle • Connective (Bone, tendon, ligaments, cartilage)

  3. Types of Tissue:Epithelial • Lining tissue • layers of cells • subject to wear • cells regeneration • role in diffusion and and bio-electrical conduction

  4. Type of Tissue: Nerve • Forms the nervous system (brain, spinal cord etc.) Basic Cell Neuron • Communication • Irritability • Conductivity • Not load bearing • Injured under too much tension or compression

  5. Type of tissue: Muscle • Smooth: involuntary and no striations • Skeletal: voluntary and striated • conductivity, extensibility, elasticity, contractility • Cardiac: involuntary and striated

  6. Type of Tissue: Connective • Fibers (collagenous, reticular and elastic) • Cells • Other macromolecules

  7. Types of Tissue: Connective • Density & Arrangement • Loose (fascia) • Dense (tendon, lig etc) • Irregular • Regular

  8. Types of Loose Tissue: Fibroeslatic • Loose network of fibers • Extensible: collagen fibers mesh • Elastic fibers

  9. Type of Loose tissue: Areolar • Very abundant • Mesh of fibers filled with holes (fluid) • Limited strength (weak)

  10. Type of Loose tissue: Reticular • Reticular fibers and cells • Near Lymph, bone marrow, liver, & spleen • Also found around nerves, muscles and blood vessels

  11. Type of Loose Tissue: Adipose • Any loose CT can accumulate fat • Very vascular • Heat dissipation • Cushion

  12. Components of Connective Tissue • Extracellular matrix • Fibers: collagen & elastic • glycoproteins • fluid

  13. Types of Tissue: Connective • Cells • resident: produce and maintain extracellular matrix • Fibroblasts: form fibers • migratory: reaction to injury (immune response) • macrophages • mast cells • Lymphocytes

  14. Collagen: 30% of proteins in human Tissue specific & wide organizational arrangement Produced by many cells Fibroblasts, chondrocytes, osteocytes Fibers: chains of amino acids with peptide links Tropocollagen: microfibrils and fibrils Bundle of fibrils form collagen fibers Extracellular matrix: Collagen

  15. Extracellular matrix: Collagen • Cross-linking: stiffness and inextensibility • Classification • Type I: skin, tendon, ligament etc. • Type II: cartilage • Type III: loose connective tissue, skin, blood vessels

  16. Extracellular matrix: Elastic • Slender & extensible • Capable of stretching over 150% of original length • Similar chemical composition collagen

  17. Proteoglycan Glycosaminoglycans Fill spaces between fibers (ground substance) negative ions hydrophilic Cells-associated glycoprotein: cell adhesion Fibronectin: cell migration Chondronectin Anchorin CII Complex glycoproteins

  18. Tissue Fluid • Filtrate of blood • Transport of materials: food, O2, waste removal • Blockage in lymphs: edema • Gives matrix gel characteristics

  19. Bone • Functions • protect • storage • levers • blood production • Dynamic: remodels and adapts to mechanical, hormonal and calcium changes • Cortical and trabercular types of bone

  20. Bone Development • Intramembranous ossification (fast) • Endochondral ossification: (limb & axial bones) • cartilage calcification • primary & secondary center of ossification • Growth plate • Zone of ranvier (circumferential growth)

  21. Bone Development • Longitudinal growth • chondrocytes activity • Three regions • growth: active cell division • maturation: synthesize & secrete EXM • transformation: calcification

  22. Bone Development • Intramembranous & endochondral ossification can occur in the same bone • Primary ossification center present at birth • Affected by loading and hormones • Trauma or fracture can affect bone growth (growth plate closure or deformities)

  23. Bone components • Osteoblast & Osteocytes • Bone formation • Osteoblast (bony surface) • Osteocyte: surrounded by matrix • Haversian, Volksman and caniliculi • Osteoclasts: bone-reabsorbing cells

  24. Bone components • Extracellular matrix: Organic, inorganic and fluid components • Inorganic: Minerals (calcium) 50% volume • Organic: Type I collagen & proteoglycans (39% of the volume) • Fluid (11%) • Mineral = stiffness organic = strength • Collagen fibers most abundant in the matrix • Marrow (canal system)

  25. Bone macrostructure • Woven Bone • disorganized pattern of collagen & osteocytes leading to lower mechanical properties. Deposited in novo for rapid mechanical support (fracture callus) • Primary • Must replace cartilage or woven bone. Multiple thin layers of matrix and cells, organized. Sparse vascular channels • Secondary • Deposited during remodeling, replaces primary bone

  26. Cartilage • Three kinds: • Hyaline • elastic • fibrocartilage • Lack intrinsic blood vessels, nerves and lymphs • Nutrients & waste: Diffusion

  27. Cartilage Growth • Interstitial growth • chondrocyte division in young cartilage • more flexible • Appositional growth • new cartilage cells beneath perichondrium

  28. Hyaline Cartilage • Glassy appearance • Covers most joints and parts of respiratory system • Strength & Stiffness • Type II collagen (90%) • Proteoglycans (Negative Ions and hydrophilic (draw water in the matrix) • tends to swell but resisted by collagen fibrils • Age  PG’s which  resilience

  29. Elastic Cartilage • Ear, larynx, epiglottis •  elastic fibers •  flexibility

  30. Fibrocartilage • Stress points due to friction • Strong & flexible (filler material) •  collagen fibers • Growth like CT • Four classes • Interarticular (meniscus) • Connecting (disks) • Stratiform (protection) • Circumferential (spacer; glenoid labrum)

  31. Tendons • Dense fibrous CT parallel fibers • Major component Type I collagen, few elastic fibers • Tendon sheath (pulley) • Peritenon • Insertion: Sharpey’s fibers (anchoring)

  32. Tendons • Myotendinous Junction • Increase surface area • reduces stress • stronger when loaded in parallel to membrane

  33. Aponeuroses & Fascia • Fibrous ribbon like tendons: Palmar aponeurosis • Fascia: all dense fibrous connective tissue that are not tendon, ligaments or aponeurosis • Interwoven mesh of fibers: stretching in all directions and some cases planes

  34. Ligaments • Dense connective tissue • hold bone to bone, resisting tensile forces • geometry of fibers specific to function •  % of elastic fibers than in tendon • Insertions • direct: similar to tendons • indirect: collagen fibers blend with periosteum • 2/3 of a ligament is water

  35. Ligaments • Sensory receptors: information about movement, position and pain • Ruffini • Pacinian corpuscles • Golgi tendon organ • Free nerve endings • Joint proprioception? • Information about changes in muscle stiffness • Yellow ligaments: mostly elastic fibers (vocal cords, ligamentum flava)

  36. Ligaments and Injury • Ankle Sprains & proprioception • ACL & gait & proprioception

  37. Skeletal Muscle Two basic elements: Contractile proteins and connective tissue

  38. Connective Tissue • Functional stiffness • Improve transmission of tension • reduce wear & tear

  39. Microstructure • Fibers • Myofibrils • Sarcomere • Myofilaments • Actin • Myosin

  40. Microstructure • Myofilaments • Sliding Filament theory

  41. Fibers Types

  42. Muscle fibers • Series & parallel arrangement • Angle of pennation • longitudinal or fusiform (parallel) • pennate (cross-sectional area)

  43. Neural Components • Motor unit: One motor neuron and all the fibers it controls • All-or-none-principle •  muscle tension • recruitment * • frequency of stimulus

  44. Mechanical Components • Muscle length • Velocity of contraction • Type of action • isometric • concentric • eccentric • Passive properties • elastic energy stored • Muscle stiffness: internal resistance by cross-bridges Total Tension Passive active Length

  45. Joints Junction between bone-bone, cartilage-bone, teeth-bone

  46. Synarthrodial Immovable & no joint cavity Amphiarthrodial slightly movable & no joint cavity Diarthrodial (synovial) movable with joint cavity Synovial joints gliding (carpals) hinge (elbow) Pivot (radio-ulnar) Ellipsoid (wrist) Condyloid (metacarparls) Saddle Ball & socket Classification

  47. Components of Synovial Joints • Joint cavity • Synovial membrane • Bursae • Intrinsic & extrinsic ligaments • Articular cartilage • Fibrocartilage

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