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Connective Tissue
Week 4
Question | Answer |
---|---|
tissue that supports, binds or separates more specialized tissues and organs | Connective organs |
Connective tissue consists of | cells and ECM |
protein fibers (collagen, elastic, and reticular) and an amorphous component containing specialized molecules (proteoglycans, multi-adhesive glycoproteins, and GAGs) that constitute the ground substance | ECM |
Connective tissue in bound by | basal laminae of epithelia |
Support Binds tissue repair defense (immune function) Nutrition Insulation Protection | Functions of connective tissue |
Forms the stroma of organs | support |
functional unit; epithelium, nerve, muscle | Parenchyma |
ground substance and fibers | ECM |
-highly vascularized and innervated -directly supplied by lymphatic vessels -all derived from messenchyme | General features of connective tissue |
exception to vascularized connective tissue | cartilage |
-Fibroblasts -Myofibroblasts -Macrophages -Adipocytes -Stem cells -Mast cells | Resident/permanent cells |
-Lymphocyte -Plasma cell -Neutrophil -Monocyte -Basophil -Eosinophil | Wandering/transient cells |
consists primarily of cells that have migrated into tissue from blood in response to specific stimuli | Wandering/transient cells |
-most common cell in connective tissue -reside close to collagen fibers -synthesize all extracellular fibers -synthesize and maintain ground substance | Fibroblasts |
In H&E, only nucleus is visible -appears as elongated or disc-like structure -cytoplasm not usually visible | Fibroblasts |
-Derived from monocytes -migrate to connective tissue and differentiate to macrophages -Phagocytic; produce cytokines -Antigen presenting cells; multinuclear giant cells | Macrophages |
Kupffer cells Microglia Osteoclasts Histiocytes Langerhans cells | Different macrophage titles -Liver, brain, bone, connective tissue, and skin |
indented or kidney-shaped nucleus, lysosomes abundant in cytoplasm irregular CM/ cytoplasmic extensions (pseudopodia) | Macrophages |
-originate in bone marrow (then lack cytoplasmic granules) -migrate to connective tissue or lamina propria or mucosae -proliferate and accumulate cytoplasmic granules in connective tissue -secretory products contained w/in granules | Mast cells |
-Secretory products w/in granules include histamine, heparin, proteases, eosinophil, neutrophil, and chemotactic factors -_________________ & basophils circulating in blood derived from same progenitor in bone marrow | Mast cells |
-Has IgE antibodies on surface (allergic reactions) -exhibits metachromasia -PAS + because of glycoprotein nature | Mast cells |
-granules w/in mast cells stain different color from color of dye initially used -due to change in electronic structure of dye after binding granule | metachromasia |
Functions: -mechanical support -structural support -influence extracellular communication -tensile strength -act as biochemical barrier and regulate metabolic functions of cells surrounded by matrix -stores water | Ground substance |
-clear, viscous substance w/slippery feel and high water content -found btw cells and fibers- space filler -can be fluid, semi-fluid, gelatin-like or calcified -contains GAGs, proteoglycans, and MAG | ground substance |
-most abundant polysaccharide in ground substance -long & unbranched -highly negative -has carboxyl and sulfate group on sugar molecules -stains well w/basic dyes -permits rapid diffusion of water-soluble molecules | Glycosaminoglycans (GAGs) |
-extremely long and rigid GAG -can hold large amount of water -only GAG that IS NOT sulfated and not modified posttranslationally -abundant in cartilage | Hyaluronan |
are responsible for physical properties of ground substance | GAGs |
-composed of GAGs covalently attached to core proteins -functions to link cells to ECM | Proteoglycans |
within ______________, GAGs extend perpendicularly from core protein in brush-like manner -core protein has sites for multiple GAG attachments | Proteoglycans |
contains both chondroitin sulfate and keratan sulfate (proteoglycans) | Aggrecan |
-have binding site for ECM proteins like collagen -have binding sites for other ECM components like GAGs and proteoglycans | Multi-adhesive glycoproteins (MAGs) |
Function: -stabilize ECM and link it to surface of connective tissue cells -regulate cell movement and migration -regulate cell differentiation and proliferation | Multi-adhesive glycoproteins (MAGs) |
MAG that is the most abundant glycoprotein -aids in cell to ECM attachment | Fibronectin |
MAG that is present in basal lamina | Laminin |
-MAG present in bone tissue -helps attach osteoclasts to bone surface | Osteoponin |
-MAG that is important in wound healing -most important during embryogenesis | Tenascin |
-strong and resilient to pulling and stretch -most abundant type of fibers in connective tissue -long, unbranched, thick and wavy -type I is most abundant | Collagen |
-provide mechanical strength (tendons, bonds- type I) -provides resistance to pressure (cartilage- type II) -provides scaffolding for cells (reticular-type III) | Fibrillar collagen |
collagen type IV collagen, VI, VII | Basement membrane collagen |
-appears eosinophilic w/H&E dyes -produced by fibroblasts: chondrocytes (cartilage), osteoblasts (bone), and pericytes (blood vessels) | Collagen |
scar raised more than normal, but w/in original wound boundary | Hypertrophic scar |
increased collagen production leads to scar extending into surrounding tissue (beyond original wound boundary) | Keloid scar |
-long, thin, and branching -allow tissues to respond to stretch and distension -composed of cross-linked elastin molecules and network of fibrillin microfibrils w/associated proteins (EMILIN-1 & MAGP-1) | Elastic |
composed of AA: glycine, proline, desmosine and isodesmosine (lysine-like) | Elastin molecules |
elastin molecules are connected by | desmosine and isodesmosine |
elastic property of the elastin molecule is related to unusual polypeptide backbone (abundant hydrophobic regions), which causes | random coiling |
found in large arteries, elastic cartilage, vocal ligament, bronchi, ligamentum flavum, suspensory ligament of penis, skin | Elastin |
special staining required- orcein, resorcin, or Verhoeff's | elastin |
produced by smooth muscle cells (blood vessels), endothelial cells (blood vessels), and chondrocytes (cartilage) | elastin |
-contains type III collagen fibers -short, thin and highly branched -argyrophilic- high affinity for silver nitrate stains -stains well w/PAS -1st type of collagen synthesized during wound healing | Reticular fibers |
-forms basement membrane & basal lamina -secreted by fibroblasts -secreted by reticular cells (hemopoietic & lymphatic tissues), Schwann cells (peripheral nerves), & smooth muscle cells (tunica media of blood vessels; and muscularis of alimentary canal) | Reticular fibers |
Functions: -form supporting network for cellular constituents of various tissues and organs -hemopoietic and lymphatic tissue (bone marrow, lymph nodes, spleen) -liver -endocrine tissue -nerve tissue | reticular fibers |
embryonic connective tisse | mesenchyme and mucous connective tissue |
loose connective tissue dense connective tissue -regular -irregular | connective tissue proper |
-cartilage -bone -adipose tissue -blood -hemopoietic tissue -lymphatic tissue | specialized connective tissue |
-gives rise to all connective tissue types -primarily found in embryo -________ cells: -stem cells -small, spindle-shaped, grossly homogenous -tapered ends that make contact w/neighbor cells via gap junctions | Mesenchyme |
-ground substance: viscous and abundant -reticular fibers (sparsely arranged) | Mesenchyme ECM |
-more viscous mesenchyme -in unbilical cord of fetus (whartons jelly), developing heart (cardiac jelly), vitreous humor of eye ______ cells -mesenchymal stem cells -spindle-shaped -great distance btw cells tapered ends are thinner and hard to see | Mucus (embryonic connective tissue) |
Ground substance: almost gelatin-like, composed of hyaluronan, imparts gelatinous consistency to the matrix fibers: very thin collagen fibers | Mucus ECM |
-abundance of varying cells and sparse, loosely arranged fibers -most cells are wandering -abundant ground substance -rich blood supply (exchange of gases and nutrients) -diffusion of hormones and growth factors | Loose connective tissue |
Location: lamina propria of mucous membranes (urinary, respiratory, and digestive tracts) surrounds blood vessels and glands | Loose connective tissue |
-abundant fibers (collagen I) and few cells (fibroblasts) -little ground substance | dense |
parallel rows of collagen fibers (unidirectional stress) tendons, ligaments, aponeuroses | dense regular |
collagen fibers haphazardly arranged (tension from all directions) dermis of skin, periosteum, organ capsules | dense irregular |
substance of tendon surrounded by thin connective tissue capsule | epitendineum |
tendon subdivided into fascicles by | endothendineum |
fibroblasts w/in tendons are called | tendinocytes |
-large cells -peripheral nucleus -one (unilocular) lipid droplet -highly vascularized -function- fat storage, energy source, insulation, protection | white adipose connective tissue |
-smaller cells -central nucleus -multilocular lipid droplet function: heat production (thermogenesis) | Brown adipose connective tissue |
small quantity of fluid btw cells of connective tissue- for solvation and diffution | Interstitial fluid |
swelling due to increased tissue fluid | edema |
_______ favored by: -increased intravascular (capillary) hydrostatic pressure -decreased intravascular oncotic pressure -increased vascular permeability | edema |
used to stain reticular fibers; stains them black | silver stain |
stains elastic fibers ex: Orcein, Verhoeff's | elastic stain |
differentiates btw nucleus, cytoplasm, and connective tissue fibers | trichrome stain |