Lect 3 107 2024-Connective tissue final (handout).pdf

BioSci 107 Lecture 3 Connective Tissues 2024 Anthony Phillips 1 The Tissues of the Body (ii): Connective Tissue 1. It binds, supports and strengthens other body tissues. 2. A major transport system of the body (blood is a connective tissue). 3. A major site of stored energy reserves (fat or adipose...

BioSci 107 Lecture 3 Connective Tissues 2024 Anthony Phillips 1 The Tissues of the Body (ii): Connective Tissue 1. It binds, supports and strengthens other body tissues. 2. A major transport system of the body (blood is a connective tissue). 3. A major site of stored energy reserves (fat or adipose tissue is a connective tissue). 2 Features of Connective Tissues Unlike Epithelia CT is NOT found on body surfaces – (Think of where bones, cartilage, blood are located…) CT can be highly vascular – (Exceptions: cartilage which is avascular and tendons with very little blood supply) Like Epithelia CT is supplied by nerves – (Exception: cartilage) 3 Connective tissue (CT) is composed of: EXTRACELLULAR MATRIX (ECM) and CELLS CT = ECM + Cells 4 CT = ECM + Cells 5 Connective Tissue Extracellular Matrix (ECM) The ECM is composed of : i) Ground Substance (GS) in association with ii) Protein Fibres (3 major types in different proportions) CT = ECM + Cells ECM = GS + Fibres The protein fibres of the ECM are secreted by the cells in the ECM/CT The structure of the ECM largely dictates the connective tissue qualities e.g. – Cartilage: ECM is firm and rubbery – Bone: ECM hard and inflexible. 6 Connective Tissue Extracellular Matrix (ECM) ECM = GS + Fibres Ground Substance 7 Connective Tissue Extracellular Matrix (ECM) ECM = GS + Fibres Ground Substance – you can make it at home ! 8 Connective Tissue Extracellular Matrix (ECM) ECM = GS + Fibres Ground Substance Ground substance is composed of a mixture of : Water Proteins (gelatin in jelly!) Polysaccharides (sugars) GS = H2O + proteins+ polysaccharides The sugars are: Glycosaminoglycans (GAGS or mucopolysaccharides). GAGS join with core proteins to form proteoglycans. 9 Some Terminology Glycosaminoglycans (GAGS) – Other name “mucopolysaccharides” – They are long unbranched polysaccharides” Repeating disaccharide unit Amino sugar e.g.: N acetylglucosamine Uronic sugar e.g. glucuronic acid Proteoglycans: Core Protein + Glycosaminoglycan (GAG) 10 Glycosaminoglycans (GAGS) Sulphated GAG examples: Dermatan sulphate Heparin sulphate Keratan sulphate Chondroitin sulphate These bind to core proteins to form proteoglycans (PGs) Non-sulphated GAG example: Hyaluronic acid Hyaluronic acid does not bind directly to protein backbone but is joined to various PGs 11 Hyaluronic acid (Bound to protein core) (no protein core) https://doi.org/10.1155/2015/834893 The glycosaminoglycan hyaluronic acid is unusual in that it is not sulphated or covalently bound to a core protein. Highly polar and attract water so collectively, the glycosaminoglycans trap water to make the ground substance more jelly-like. Glucuronic acid and Nacetylglucosamine (Dissacharide in hyaluronic acid) 12 Applications of GAGS Hyaluronic Acid: viscous slippery substance binds cells together, lubricates joints and maintains shape of eyeball Hyaluronidase: produced by white blood cells, sperm and some bacteria. This makes ground substance more liquid so they can move more easily in it or makes access to the egg easier for sperm. 13 Application of GAGS as part of ground substance Chondroitin Sulphate: support and provide the adhesive features of cartilage, bone, skin, blood vessels. Keratan Sulphate: found in bone, cartilage, cornea of the eye Dermatan Sulphate: found in skin, tendons, blood vessels, heart valves Sometimes can get abnormal ECM ground substance 14 Periorbital ECM deposition and thyroid disease (Exophthalmos) Indian J Dermatol Venereol Leprol 2013;79:41-51 15 NO more detail needed than this slide Abnormal Periorbital ECM and thyroid disease (Exopthalmos) Most common in younger women Goitre (swollen thyroid gland) Autoimmune over-activation of thyroid (goitre) Autoimmune action on fibroblasts in ECM of eye (exophthalmos) The deposition of glycosaminoglycans and the influx of 16 Indian J Dermatol Venereol Leprol 2013;79:41-51 water increase the orbital contents NO more detail needed than this slide http://medicine.academic.ru/pictures/medicine/562.jpg N Engl J Med 1993; 329:1468-1475 Panel A thick periorbital tissues Panel B normal tissues 17 RECALL: CT = ECM + Cells ECM = GS + Fibres The ECM is composed of : i. Ground Substance in association with ii. Three different major types of Protein Fibres* in different proportions (*proteins secreted by the cells in ECM). 18 CT = ECM + Cells ECM = GS + Fibres There are 3 different types of connective tissue fibres in the extracellular matrix (ECM): i) Collagen fibres (thick) Very strong but flexible to resist pulling forces Features vary in different tissues e.g. more water around collagen in cartilage than in bone. Collagen 25% of your body and is most abundant protein! Common in: bone, cartilages, tendons and ligaments Parallel bundles Collagen with a fibroblast 19 ii) Reticular fibres Composed of collagen with coating of glycoprotein Collagen in fine bundles with coating of glycoprotein (more protein than sugar) Made by fibroblasts Provide strength and support Form part of the basement membrane Thinner, branching - spreads through tissue. Form networks in vessels and through tissues especially adipose tissue, nerve fibres, smooth muscle tissues Branching reticular fibres 20 iii) Elastic fibres Thinner than collagen fibres Fibrous network Consist of the protein elastin surrounded by the glycoprotein fibrillin to give more strength and stability. Can be stretched 150% without breaking Found in skin, blood vessels and lung. Elastic fibres 21 Marfan Syndrome A hereditary defect in elastic fibres usually resulting from a dominant mutation in a gene on chromosome 15, which codes for fibrillin. Fibrillin is a large glycoprotein (350 kDa) that contributes to a structural scaffold for elastin. Thumb and little finger overlap, when grasping the wrist of the opposite hand Body produces growth factor Transforming Growth Factor beta(TGFb) – increases growth because does not bind normally to fibrillin to keep it inactive (theory). Individuals with Marfan Syndrome are: usually tall, long limbed, and often with a chest deformity (e.g. protruding or collapsed sternum). Normal life span but need medical vigilance to control BP etc Abraham Lincoln ? Maybe had it? They may have weakened heart valves and arterial walls, which can be life threatening. Occurs in about 1 in 20,000 live births. (THIS SLIDE content is ALL you need to know!) Harpers, 1864 Hand image: By Staufenbiel I, Hauschild C, Kahl-Nieke B, Vahle-Hinz E, von Kodolitsch Y, Berner M, Bauss O, Geurtsen W, Rahman A http://www.ncbi.nlm.nih.gov/pubmed/24165013, CC BY-SA 2.0, 22 Images: wikipedia CT = ECM + Cells 23 Two Common Connective Tissue Cell Types Cell Type Fibroblasts Location Widely distributed in connective tissues; migratory Ariadna Mendoza-Naranjo et al ; doi:10.1371/journal.pone.0037374.s006 Function Secrete components of the matrix (fibres and ground substance) 24 Image: wikipedia Two Common Connective Tissue Cell Types Cell Type Fibroblasts Adipocytes (fat cells) Location Widely distributed in connective tissues; migratory Under skin and around organs Connective tissue fibroblasts Function Secrete components of the matrix (fibres and ground substance) Store fat (triglycerides) 25 Image: wikipedia Other cells found in Solid CT Macrophages (Histiocytes) Phagocytic cells Fixed and wandering forms in connective tissues (CT) Fixed: “Dust cells” (lung); “Kupffer cells” (liver); “Langerhan’s cells” (skin) Wandering in CT: sites of infection/inflammation/ injury Many CT sites but especially in gut and lung, salivary glands, lymph nodes, spleen, red bone marrow Plasma cells From Blymphocyte. These produce antibodies Mast cells Produce histamine that dilates vessels Alongside blood vessels Leucocytes White blood cells E.g. neutrophils, eosinphils Migrate out from blood Images: Wikipedia 26 Classification of Connective Tissue: Embryonic OR Mature 27 a. Embryonic Connective Tissues Type Structure/Location/Function i) Mesenchyme (embryonic) Gives rise to all other connective tissues. Consists of connective tissue cells (mesenchymal cells) in a semi-fluid ground substance containing reticular fibres (see images above). ii) Mucous Mucous CT has widely scattered fibroblasts embedded in jelly-like ground substance. Supports Umbilical cord of foetus. 28 b. Mature Connective Tissues Going to review 5 of them. (Sometimes call Specialised CT’s) 29 Mature Connective Tissue: 1. Loose Connective Tissue (a) Areolar Connective Tissue (most common form of CT) Type Sub-type Structure/Location/Function Loose (Many cells, fewer fibres) Areolar Three types of fibres are present (collagen, reticular and elastic). Widely distributed around almost every structure. Like a “packing material”. Strength, Elasticity, Support. 30 (1. Loose Connective Tissue) (b) Adipose Connective Tissue Buttocks; flanks; abdomen; orbit of eye Type Sub-type Structure/Location/Function Loose (Many cells, fewer fibres) Adipose Adipocytes dominant. Central triglyceride droplet. Found with areolar connective tissue (incl. fibroblasts). White adipose (energy storage) and Brown adipose (heat production). 31 Insulation. Energy source. Temperature control YOU look up c) Reticular connective tissue. 32 2. Dense Connective Tissue Dense Regular Connective Tissue Type Sub-type Structure/Location/Function Dense (More fibres, fewer cells) Regular Tendons (muscle to bone); Ligaments (bone to bone); aponeuroses (muscle to muscle). Regularly arranged collagen e.g. tendons (pulling along the fibre axis). Shiny white colour; Collagen fibres are not a living tissue; Slow healing 33 Attachment. 2. Dense Connective Tissue YOU look up “Dense Irregular” and “Dense Elastic” connective tissues 34 b. Mature Connective Tissues Going to review 5 of them. 35 3. Supporting CT: Cartilage Hyaline Cartilage Type Sub-type Cartilage Hyaline (Dense network of collagen and elastic fibres) Structure/Location/Function Abundant. Relatively weak, resilient gel in which fibres are present but not obvious. e.g. anterior ends of ribs; respiratory cartilage – i.e. nose, trachea, bronchi. Nasal septum, ends of long bones. 36 Flexibility and movement. 3. Supporting CT: Cartilage YOU look up Elastic and Fibrocartilage. 37 4. Supporting CT: Bone or osseous tissue Bones are organs composed of several connective tissue types, including bone tissue (which is either compact or spongy (BM)). Compact bone Outer layer of bone and forms the shaft of long bones. It is also known as cortical bone. Composed of many rod-shaped units known as either Osteons or Haversian systems (see soon). Spongy bone Porous inner bone tissue that lies underneath compact bone. Also known as Cancellous bone Lacks osteons Wikipedia 38 4. Bone or osseous tissue (Bone CT=ECM (mineralised)+ cells) Bones are composed of several connective tissue types, including bone tissue (which is either compact or spongy). Compact bone Type Sub-type Structure/Location/Function Bone Compact Compact contains osteons. Stores calcium & phosphorous. Protection & support. Spongy 39 Lacks osteons, stores triglycerides (yellow marrow) and produces blood cells (red marrow). Bone cells (this is all detail you need to know about these) (Bone CT=ECM (mineralised)+ cells) Four cell types are found in bone. 1. Osteogenic cells: mesenchymal stem cells that develop, starts to lay down collagen; become trapped and become osteoblasts. 2. Osteoblasts: boneforming cells. Lay down more collagen, mineralization process starts. 3. Osteocytes: mature bone cells derived from osteoblasts trapped within the extracellular matrix. Maintain bone tissue. Involved in exchange of nutrients and wastes. Have gap junctions. 40 multinucleated 4. Osteoclasts: Large, Multinucleated cells Formed from the fusion of blood monocytes Break-down bone 41 The Structure of Osteons (Haversian Systems) The basic unit of compact bone is the osteon, with four parts: 1. Lamellae: 2. Lacunae: 3. Canaliculi: 4. Central (Haversian) canal Osteons are aligned along lines of stress (e.g. long axis of bone shaft). 42 Osteon Structure 1. Lamellae: concentric rings of mineral salts for hardness (e.g. calcium phosphate and calcium hydroxide, which together form hydroxyapatite) and collagen (for tensile strength). Marrow site osteocyte 43 Osteon Structure 2. Lacunae: small spaces between lamellae that contain mature bone cells (osteocytes) Marrow site osteocyte 44 Osteon Structure 3. 4. Canaliculi: “minute canals” (containing EC fluid and minute osteocytic processes) that radiate from lacunae and provide routes for oxygen, nutrients and waste. Central (Haversian) canal: blood, lymph and nerves Marrow site osteocyte 45 Osteoclasts reabsorb dead bone Chondroblasts lay down hyaline cartilage callus Osteoblasts lay down new bone Osteoclasts remodel new bone Comminuted mid-shaft humeral fracture (with callus) 46 Wikipedia image Image: Ghiasi et al ; Bone Reports 6 (2017) 87–100 47 b. Mature Connective Tissues Going to review 5 of them. 48 5. Liquid Connective Tissue (Blood CT=ECM (plasma) + Cells) Blood (RBC no nucleus) Type Sub-type Structure/Location/Function Liquid Blood Consists of blood plasma (a liquid extracellular matrix) and formed elements (red cells, white cells and platelets) 49 Images: http://www.atlantaplasma.com/what-is-plasma “Formed elements” of blood Need Mabs to distinguish + Immature mast cells (Granule status) Erythrocytes transport oxygen and carbon dioxide Secrete Abs Leukocytes combat disease: i. Neutrophils and monocytes (macrophages) are phagocytic, engulfing bacteria. ii. Basophils (mobile) and Mast cells (immature circulate; mature are fixed in tissues), release substances (e.g. histamine) that intensify the inflammatory reaction. iii. Eosinophils are effective against certain parasitic worms and in acute allergic response. iv. Lymphocytes are involved in the immune response. Platelets (from megakaryocytes in red marrow): clotting. Image: wikipedia 50 Connective Tissue Structure Connective tissue is composed of cells and the matrix between them 51 Connective Tissue Structure 52 Text Book Resources Tortora and Derrickson: 3rd Asia Pacific Edition pg 161-176 2nd Asia Pacific Edition pg 189-205 Other editions a. 14th Edition Pg 121-131 b. 13th Edition Pg 128-140 Image Acknowledgements: Various editions of the course text books and also from Martini and Ober: (Chapter 4.7 - 4.11 inclusive) 2015 Edition or Wikipedia (free creative commons) were the 53 sources for the images used in BioSci 107 Lectures 1-5 in 2022; unless otherwise stated.