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Connective tissue Dr. Maria Zahiri 3

Four basic tissue types:  Epithelial tissue (surfaces and glands)  Connective tissue  Muscle tissue (contractile cells)  Nervous tissue 4Dr. Maria Zahiri

Main roles of connective tissue o Mechanical support o binding cells into tissues o Binding tissues to each other o Protection and Defense o Serving as a medium for exchange o Storage (water, ions, minerals, Growth factor) o Energy supply Dr. Maria Zahiri5

What's the contents of connective tissue? connective tissue cellsECM (Extra cellular matrix) Fibers Ground substance Fluid Dr. Maria Zahiri6

Classification Dr. Maria Zahiri7  CONNECTIVE TISSUE PROPER  SPECIALISED CONNECTIVE TISSUES  adipose tissue  haemopoietic tissue (bone marrow, lymphoid tissue)  blood  bone and cartilage

The cells Cells of connective tissue MesenchymeAdult Fixed Cells Fibroblast Macrophage Adipose cells Mast cells Undifferentiated mesenchyme cell Wandering Cells Lymphocytes Plasma cells Blood cells Dr. Maria Zahiri8

Mesenchymal cells  Small fusiform or stellate cells  Have delicate chromatin pattern  Pluripotential Dr. Maria Zahiri9

Fibroblast  are most common cells of C.T.  Produce and secrete ECM  Active fibroblast has more cytoplasm include of developed RER, Golgi apparatus and euchromatic nucleus = activated (wound healing)  Inactive fibroblast (Fibrocyte) has flattened nuclei, sparse cytoplasm  Fibroblasts may differentiate to adipose cells or chondrocytes Dr. Maria Zahiri10

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wound healing Dr. Maria Zahiri12

 Myofibroblast : are modified fibroblasts They have bundle of actin similar to smooth muscle cells Abundant in wound healing ( wound contraction)  Activated Fibrocyte = fibroblast wound healing Dr. Maria Zahiri13

Macrophage  Origin: bone marrow monocyte ( in blood) Macrophage in C.T.  Irregular membrane surface; nucleus may be oval and is eccentric  Size: micro  Phagocytosis of cell debris and micro organisms  Presenting antigens to lymphocytes  RBC turnover in spleen  Secretion of cytokins, enzyme Dr. Maria Zahiri14

The mononuclear phagocyte system (MPS) (also called Reticuloendothelial System or Macrophage System) Dr. Maria Zahiri15  is a part of the immune system  consists of the phagocytic cells  located in reticular connective tissue

Antigen-presenting cell ( APC ) or accessory cell Dr. Maria Zahiri16  These cells process antigens and present them to T-cells.

Epithelioid cells or multinuclear giant cells Dr. Maria Zahiri17  In chronic inflammation  is a mass formed by the union of several distinct cells (usually macrophages), often forming a granuloma.  It can arise in response to an infection  Granulomas form when the immune system attempts to wall off substances it perceives as foreign but is unable to eliminate.

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Mast cell  Cytoplasm full of granules containing heparin, histamine, proteases, chemotactic factors, chondroitin sulphate  Size: micro  Centeric nucleus  Originate from bone marrow stem cell Dr. Maria Zahiri19

- Immediate hypersensitivity reaction - Slow reaction Dr. Maria Zahiri20

'Eosinophil Chemotactic Factor Dr. Maria Zahiri21  a peptide that is chemotactic for eosinophilic leukocytes and is released from disrupted mast cells

Anaphylaxis Dr. Maria Zahiri22

Plasma cell  Common in intestinal lamina propria and glands secreting immunoglubulins such as lacrimal glands, salivary glands, and mammary gland  Oval cell with basophilic cytoplasm, clock face nucleus  Differentiate from B - lymphocytes  Life span days Dr. Maria Zahiri23

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Adipocyte Dr. Maria Zahiri25

Others  Neutrophils  Eosinophils  Basophils  Lymphocytes - small, heterochromatic nucleus Dr. Maria Zahiri26

Fibers  Collagen fibers  Elastic fibers  Reticular fibers Dr. Maria Zahiri28

Collagen fibers  Staining ( Eosin - pink; Mallory’s - blue; Masson’s – green)  Physical feature Dr. Maria Zahiri29

Chemical components  prolin  lysin  Hdroxy prolin  Hydroxy lysin Dr. Maria Zahiri30

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Biosynthesis Dr. Maria Zahiri32

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Disorders:  Osteogenesis imperfecta (gene or amino acid)  Progressive systemic Sclerosis (fibrose- keloid)  Vitamin C is a co-factor for prolin hydroxylase Dr. Maria Zahiri35

Reticular Fibers (Collagen type III)  Staining (Argylophilic- PAS)  Physical feature  Formative cell  Disorders ( ehlers-Danlos IV) Dr. Maria Zahiri36

Ground substance Dr. Maria Zahiri37  is the background material within which all other connective tissue elements are embedded.  consist of a complex of glycosaminoglycans (GAGs), proteoglycans, and glycoproteins

Classification Dr. Maria Zahiri38  CONNECTIVE TISSUE PROPER  loose irregular connective tissue  dense irregular connective tissue

CONNECTIVE TISSUE PROPER loose irregular connective tissue Dr. Maria Zahiri39  includes areolar tissue, reticular tissue, and adipose tissue  is the most common type of connective tissue in vertebrates  It holds organs in place and attaches epithelial tissue to other underlying tissues.  It also surrounds the blood vessels and nerves.  fibroblasts are widely dispersed in this tissue

Areolar tissue Dr. Maria Zahiri40  is a common type of loose connective tissue (and the most widely distributed type of connective tissue in vertebrates  Many adjacent epithelial tissues (which are avascular) get their nutrients from the interstitial fluid of areolar tissue; the lamina propria is areolar in many body locations.  Its fibers run in random directions and are mostly collagenous, but elastic and reticular fibers are also present.

Function Dr. Maria Zahiri41  hold organs in place and attaches epithelial tissue to other underlying tissues  It also serves as a reservoir of water and salts for surrounding tissues. Almost all cells obtain their nutrients from and release their wastes into areolar connective tissue.

Location Dr. Maria Zahiri42  is found beneath the dermis layer and is also underneath the epithelial tissue  It is also a component of the lamina propria of the digestive and respiratory tracts,  the stroma of glands  the hypodermis of the skin  It is also found in the mesentery which is surrounding the intestine

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Dense connective tissue Dr. Maria Zahiri47  is enriched in collagen fibers with little ground substance  If the closely packed bundles of fibers are located in one direction, it is called regular (tendons)  if oriented in multiple directions, it is referred to as irregular (dermis)

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Scars Dr. Maria Zahiri50  are areas of fibrous tissue (fibrosis) that replace normal skin after injury.  A scar results from the biological process of wound repair in the skin and other tissues of the body.

Dr. Maria Zahiri51  Scar tissue is composed of the same protein (collagen) as the tissue that it replaces, but the fiber composition of the protein is different  This collagen scar tissue alignment is usually of inferior functional quality to the normal collagen randomised alignment.  For example, scars in the skin are less resistant to ultraviolet radiation, and sweat glands and hair follicles do not grow back within scar tissues.

Dr. Maria Zahiri52  A myocardial infarction, commonly known as a heart attack, causes scar formation in the heart muscle, which leads to loss of muscular power and possibly heart failure.  However, there are some tissues (e.g. bone) that can heal without any structural or functional deterioration.

Types Dr. Maria Zahiri53  Hypertrophic  Keloid  Atrophic  Stretch marks