| 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 |
