Connective Tissue PDF

Connective tissue Dr Pip Garner [email protected] School of Pharmacy and Medical Sciences CLS4011 Connective tissue Learning Objectives; To know the different kinds of connective tissues in the body To understand their roles in the body To understand that properties deriv...

Connective tissue Dr Pip Garner [email protected] School of Pharmacy and Medical Sciences CLS4011 Connective tissue Learning Objectives; To know the different kinds of connective tissues in the body To understand their roles in the body To understand that properties derive from both the cells and the ECM To be able to recognize these different tissue types To understand how structure relates to their function (of both the tissues as a whole and also their constituent parts) To understand what rickets is, and how a change in structure has resulted in a lack of functionality  Connective tissue Connective tissue is one of four sets of tissues found in the body (the others are neural, muscle and epithelial) Is comprised of 2 components: Extracellular matrix and Cells Different types of CT are dependant on the abundance and type of both the ECM and Cells (specialised: cartilage and bone or proper) -Connective Tissue is involved in: 1) Packaging and dividing, 2) Providing support, 3) Energy storage 4) Space filling Connective tissue Deep tissues – never exposed to environment outside of body. Support and bind other tissues (cartilage). Store nutritional substances (fat). Produce protective and regulatory substances (ECM). Most diverse tissue (bone, blood, fat etc)  Connective tissue 3 basic components: Secretecollageis Specialised cells - Fibroblast, osteocyte bone cell responsible for ↳ maintaining matrix bony Protein fibres - Collagen Ground substance Fills all spaces between cells. Fibres and ground substance = matrix Largest volume of CT  Support cells Fixed , do not migrate Fibroblasts collagen Chondrocytes cartilage tissue Osteocytes bone Myofibroblasts muscle Adipocytes Fat Adipose Tissue , Extracellular Matrix Elastin = elastic - Structural carbohydrates Cell Cell - Structural protein - eg collagen Cell - Fibre All bathed in ground substance, a clear, colourless fluid  Connective tissue fibres bones , tendons ligaments Collagen , liver + spleen need Long, straight, branched, strong, more support = more reticular tissue flexible Reticular Liver , spleen Thinner than collagen, forms branching interwoven network Elastic Heart Branched, wavy, after stretching returns to normal  Classification Different types of CT are dependant on the abundance and type of both the ECM and Cell Classification- Proper Cells (embedded); Fibroblasts Adipocyte Mesenchymal cells (MSC) Cells (migrating) Macrophages Mast cells Lymphocytes Plasma cells Produces collagen, elastic and reticular fibres. Dense Regular CT Dense regular Appears white Densely packed collagen fibres parallel to direction of force Few cells (fibroblasts) Poor vascularity – repairs slowly Tendons and ligaments Prevents constant breaking · but when It breaks , takes What property? to heal + recover long Dense Irregular CT Dense irregular Densely packed collagen fibres Fibres in multiple directions due to multiple axis of stress Few cells (fibroblasts) Dermis of skin Fibrous joint capsules What properties? Elastic CT Elastic fibres that can stretch 1.5 times and return. walls of large arteries What properties? · strong Loose CT Loose Flexible strength in all directions Role Fills spaces between organs Supports epithelia Protects Specialized cells in organs Reticular CT Jellylike matrix Reticulin fibres (Collagen III) form fine network around epithelial cells. Forms framework of high cellularity organs such as liver and spleen Adipose CT Cells store fat droplets. Acts as food reserve, protects organs and insulator. Areolar CT Loose Fibres “empty space” = ground substance Cell types Fibroblasts Macrophages Mast cells Roles Fills space Binds skin to underlying organs Site of tissue fluid (water and salt reserve) Classification Specialised - Cartilage -cartilage Cell – chondrocyte Semisolid matrix with elastic properties Supportive and protective CT frequently associated with bone Avascular (difficult to heal) Three types – based on type and amount of fibres embedded within matrix Cartilage Three major types: 1. Hyaline cartilage 2. Fibrocartilage 1. Elastic cartilage Hyaline cartilage Translucent matrix Most common type Player of dense Irregular CT Covered by dense perichondrium tissue that surrounds cartilage Matrix contains closely packed collagen fibres Provides tough but flexible support Elastic cartilage Contains elastic fibres: resilient and flexible Tolerates distortion Outer ear, epiglottis Epiglottis = sheet of small leaf-shaped that protects elastic cartilage and helps you swallow larynx Fibrocartilage Matrix dominated by large collagen fibres which are densely interwoven Tough and durable: Resists compression Absorbs shocks Prevents damaging bone to bone contact Absorbs Shock Specialised – Bone Function of bones Complex and dynamic living tissue. Continuously going through a process called bone remodelling. Contributes to homeostasis of the body. Bone Cells – osteoblast, osteoclast, osteocyte Rigid – hardness due to calcium phosphate Flexibility due to collagen fibres Metabolically active Rich vascular supply Two types: Compact or dense (hard outer layer) Spongy or cancellous (porous, vascular inner layer that provides space for marrow and blood cells. Histology of Bone Four types of cell are present in bone tissue: 1. Osteoprogenitor cells- tissue from which almost all connective tissue are formed 2. Osteoblasts- Secrete collagen fibres to build extracellular matrix of bone tissue. 3. Osteocytes- entombed osteoblast, mechanosensory and mechotransmission role, maintain daily metabolism of bone tissue, such as exchange of nutrients with blood. 4. Osteoclasts- releases powerful enzymes that digest the protein and mineral components of the extracellular matrix.  OsteoBlasts Build bone (Secrete collagen fibres to build ECM) And osteoClasts Consume bone. (Release enzyme to digest protein and minerals in ECM) Compact Bone Functional unit: osteon/haversian system Osteocytes arranged in concentric layers around central canal with blood vessels Lamellae of osteon form cylinders around central canal Blood vessels supply blood to osteons Surrounded by periosteum A fibrous sheath that covers bones ( Spongy Bone Lamellae form rods – trabeculae Frequent branching thin trabeculae create open network Nutrients via canaliculi (pores] Red marrow is found between S trabeculae makes red blood cells Rickets What is this? weak /softened bones in children connective Tissue Which connective tissue does this relate to? supporting How does it present? Painful bones Spontaneous Cramps , muscle weakness , problems + spasms, breaks, dental growth slowed , What causes it? Lack Sunlight (UV) Vitamin D of > - deficiencies + calcium Why is it on the increase? increased (due Sun exposure sun risk) protection being inside due to of zo melanoma children , lack more Treatments? Exposure to sun 1 hour day a , vitamin supplements Ur radiation Activation of calcium mineralises * > > - bones Vitamin D - on skin Summary Diverse tissue Basic components Classification Connective tissue proper Fluid connective tissue Supporting connective tissue Recommended reading Guyton and Hall textbook of Medical Physiology. Physiology (Linda Costanzo).