connective tissue

1) structure 2) fat depot for insulation, energy store, and cushioning 3) Defense and protection 4) Nutrition

mesoderm and ectoderm

fixed migratory

1) active fibroblasts- synthesize and elaborate components of ECM so have all the organelles needed: basophillic cytoplasm because have lots of golgi and rER with projections that increase the cell’s surface area of ECM and allow for growth 2) inactive-(quiescent or fibrocytes)- spindle-shaped, decreased level of projections, less golgi and rER, cytoplasm is eosinophillic, nucleus elongated and heterochromatic, nucleoli not visible

decreases activity and causes degradation of the ECM

• mRNA makes three triple helices that make an alpha triple helix together. • hydroxylation of specific prolysl and lysyl residues on alpha helix of collagen fiber in the rER- VITAMIN C DEPENDENT (IMPORTANT) • -There are propeptides that make collagen soluble • collagen processed internally by fibroblasts • triple helix packaged in vesicles and delivered to golgi and then packaged into secretory vesicles that go out to ECM to be made into fibrils and larger fibers • must be made insoluable first- DONE BY PROCOLLAGEN PEPTIDASES THAT ENZYMATICALLY CLEAVE PROPEPTIDES INTO COLLAGEN FIBERS (IMPORTANT)

• resemble fibroblasts and smooth muscle • CONTRACTILE capablity • have actin and myosin • more numerous in wound healing • involved in Dupuytren’s contracture- microvascular ischemia that leads to palmar aponeurosis

microvascular ischemia that leads to trauma in palmar aponeurosis (triangle in hand) hand deformity that causes knots in the tissues due to tissue repair that involves fibroblasts and myofibroblasts that replace Collagen type I with Collagen type III when elongation occurs to repair original wound. excess Collagen III crosslinks with myofibroblasts and causes deformation digits 4 and 5 usually (progressive)

• they are white adipocytes • single droplet not bound by a membrane but ensheathed by vimentin • nucleus pushed to periphery by developing lipid droplet • lipid disintegrates when tissue processed so see void area with a signet ring (cytoplasm) • around signet ring is vimentin ***

• they secrete leptin in well fed state, mutation =mobrid obesity • the lipid also serves as an energy depot and move stored triglycerides out to become free fatty acids in starvation

loss of fat some places and abnormal amount other places

• BROWN multilocular adipocytes • smaller than unilocular cells • have lots of mitochondria • have multiple fat droplets in cytoplasm • no membrane but ensheathed in vimentin • nucleus is spheracle and not displaced peripherally

• claim to fame- metachromatic granules • derived from bone marrow and stem cells • made up of heparin, histamine, leukotrienes etc • located near blood vessels and epithelial tissue in respiratory and GI tract • mediate inflammatory responses • when IgE and antigen complex bind FC receptors on mast cells, cause release of leukotrienes (asthma bronchospasm) and histamines (swelling/mucus), heparin

• monocytes that emigrate from blood to connective tissue where they develop into macrophages • oval nucleus (central) and well endowed with golgi and rER that make lots of lysosomes • typically endented • FXN: present antigens to lymphocytes and they also phagocytose cellular debris and microorganisms • in chronic inflammatory states, activated macrophages fuse together to form epithelial like cells called GIANT multinucleated cells

-macrophages that have fused together to make larger epithelial-like cells that are a response to chronic inflammation

plasma cells and leukocytes

• derived from B lymphocytes • near antigens in connective tissue • large, oval shaped nucleus • 1) CLOCK-LIKE APPEARANCE OF NUCLEUS- projections that are made up of heterochrom. at periphery and euchrom. at center • 2) large negative golgi 3) Major basophilia because have lots of rER due to synthesis of IMMUNOGLOBULINS (antibodies) that are released constitutionally to plasma membrane (therefore no storage vesicles)

• sites of inflammation attract them • first wave- mainly neutrophils (day 1) • second wave- mainly monocytes (day 2)

1) mesenchymal 2) mucus

loose dense- regular- collagenous and elastic/irregular

• cartilage • bone • bone marrow • blood • adipose

• theyre a mesenchymal MMMMess! • abundant, gel-like- amorphous with glycoproteins and glycosaminoglycans • fibers:scattered • cells- mesenchymal • location: embryonic intermembranous bone formation

• jelly like • contains hyaluronic acid and glycoproteins • Fibers: collagen I and III • cells: fibroblasts • Location: umbilicle cord as wharton’s jelly

• abundant, viscous, amorphous with hyaluronic acid, glycosaminoglycans, proteoglycans, and glycoproteins • Fibers: ***loose collagen, reticular and elastic fibers arrangement • cells: fibroblasts, macrophages, adipose cells, mast cells, undifferentiated cells • Location:immediately deep to epithelium surrounding blood vessels