Connective Tissue.docx

Connective Tissue Tissue that supports, protects, and gives structure to other tissues and organs in the body. Has abundant ECM. Parenchymal cells – provide main function of a tissue Support cells – provide ‘scaffolding’ for the tissue Connective tissue can be separated into 2 types - loose and den...

Connective Tissue Tissue that supports, protects, and gives structure to other tissues and organs in the body. Has abundant ECM. Parenchymal cells – provide main function of a tissue Support cells – provide ‘scaffolding’ for the tissue Connective tissue can be separated into 2 types - loose and dense there is also specialised types. Specialised connective tissue: Dense regular – found in tendons and ligaments Cartlidge Adipose tissue Haemopoietic tissue Blood Bone 5 Main cells which make connective tissue Fibroblast – secrete ECM components (usually collagen and elastin), creates areola tissue (loose connective tissue) and dense (regular or irregular) tissue Chondrocytes – secrete ECM components for Cartlidge Osteoblasts – secret ECM components for bone Myofibroblasts – secret ECM components and contractile functions Adipocytes – stores lipids (energy store), supporting cells, acts as padding in some anatomic regions Extra features of connective tissue: Embryological derivation from mesenchyme Production of variety of ECM components When mature formation of sparsely cellular tissues where matric is main component Cell adhesion mechanisms that interact with ECM rather than other cells. ECM Composed of fibrillar proteins and ground substance e.g. Collagen and Elastin Ground substance – contains GAGs, hyaluronic acid glycoproteins (aggrecan). It is transparent/ colourless resides in-between fibres and cells Collagen – Most abundant. Flexible, tensile strength, collagen fibrils, wavy Type 1 – Tendons, Ligaments, skin and bone Type 2 – Cartlidge Elastic – Thinner, arranged in branching pattern, allow tissue to stretch and distend, interwoven with collagen. Reticular – Thin and short, form fine meshwork, type 3 collagen Name Denotations of Roles “-blast” = build “-cyte” = maintain “-clast” = remove Fibroblasts Secrete collagen and elastin Least specialised but can differentiate into other cells found in ECM Spindle shaped actively secrete matrix Cytoplasm is basophilic so stains a lot using H&E stain Mature adults’ fibroblasts are less active and called fibrocytes (are stained less using H&E) Bone Made up of osteoblast, osteoclasts and osteocytes ECM of bone is produced by osteoblasts and is called osteoid (majority collagen type 1) Cartlidge Hyaline Cartlidge – rounded irregularly and doesn’t look abundant (sparsely separated) Fibrocartilage – elongated and looks fibrous Elastic Cartlidge – rounded irregularly and looks abundant Adipocyte Intracellular storage of fat 2 types: unilocular (very large lipid droplet) and multilocular (small lipid droplets) If mitochondria present, then adipose tissue will be brown instead of white due to Iron in mitochondria. Myofibroblasts Important for injury response Spindle shaped cells secrete collagen also have contractile functions When glands are present myo-epithelial cells tie between epithelial cells and basement membrane of duct Examples of cells within connective tissue include: macrophages, mast cells and plasma cells