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44 Cards in this Set
- Front
- Back
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dense connective tissues
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regular and irregular
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What is a fibroblast?
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The most common cells in CT. They make collagen, elastin and, proteoglycans and glycoproteins. Elongated cell, irregular cytoplasm, ovoid nucleus with prominent nucleolus.
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What is a fibrocyte?
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Inactive fibroblast. Darker staining nucleus than fibroblast. Spindle shaped.
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What is extracellular matrix?
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Major component of CT. Made of collagens, elastin, glycoproteins (fibronectin and laminin) and proteoglycans.
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What is ground substance?
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Amorphous, viscous intercellular substance, rich in proteoglycans, that serves to regulate the amount of water in CT and acts as a barrier to foreign substances.
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What is an integrin?
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A receptor protein
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What is stroma?
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Supports, divides and organizes the organ.
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What is mesenchyme?
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Stem cells thought to give rise to several kinds of CT and to smooth muscle cells. Most are of mesodermal origin.
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What is the mesoderm?
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The middle layer of the embryo which is the point of origin of CT cells, blood, endothelial and smooth muscle cells.
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What are mast cells?
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secretory cells with many large granules containing heparin and histamine.
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Describe 2 types adipose cells.
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ulilocular- yellow fat consisting of cells with one large drop of fat in the cytoplasm. multilocular- brown fat present in fetuses and newborns with several lipid drops and mito that can produce heat rather than ATP.
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WHat type of cells have ECM? Which don't
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Cells that are attached produce ECM, while cells that are free floating like erythrocytes and lymphoid cells do not.
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What is the role of plasma cells in CT?
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These are rare in CT, but can be found in areas exposed to bacteria and foreign proteins and in areas of chronic inflammation. Derived from B lymphocytes and they make immunoglobulins.
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What is the role of eosinophils, lymphocytes and neutrophils in CT?
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These are white blood cells that are present in CT, particularly during inflammation.
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What is collagen?
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Multigene family of proteins of 25+ molecular types. Type is determined by composition of polypeptide chain. Specialized for diff functions and sythesis is developmentally regulated.
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Describe Collagen I
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fibers, bundles in skin, tendon, ligament, organ capsules, bone teeth. Most abundant.
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Describe Collagen II.
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microscopic fibrils found in cartilage, provides Resistance to pressure.
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Describe Collagen III.
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fibrils in many organs and blood vessels. Reticular. Provides structural maintenance in expandable organs.
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Describe Collagen IV.
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Non-fibrillar network found in all basement membranes. Provides support of delicate structures and filtration.
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What are the 3 main types of connective tissue fibers?
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Collagen, reticular and elastic fibers.
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What is a fibril?
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Closely packed microfibril bundles of tropocollagen.
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Describe reticular fibers.
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Made of type III collagen. They form a complex web in support of epithelial components of glands and some organs. Stained black by silver salts. Found in smooth muscle, endoneurium, and organs subjected to changing form or volume.
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Describe reticular layer.
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Thicker layer of dermis composed of irregular dense CT and therefore has more fibers and less cells than papillary layer.
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Describe papillary layer.
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outermost layer of dermis made of loose CT, fibroblasts, mast cells and macrophages. Papillae are projections that interdigitate with epidermal projections. Looks like fingers reaching toward surface.
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Describe elastic fibers.
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Fibers that stretch in response to tension. Looks thinner on slide than collagen fiber and stains. darker. Made of elastin protein. Found in blood vessels, skin, ligaments, etc.
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Describe elastin
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a fibrillar, rubbery protein found in distensible tissues like aorta, ligaments and skin. In e microscope looks like blob with smal microfibrils on periphery.
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Describe fibronectin
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Aids in attachment of fibroblasts to collagen and in anchoring epi cells to ECM proteins
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What is laminin?
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A large cruciform protein that binds to type IV collagen, to h.s. proteoglycan and to cells. Found ONLY in basement membrane.
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Describe basement membrane.
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Specialized ECM. Sheetlike structures b/w endo and epithelium or b/w epi and connective tissue.
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What is the role of a macrophage?
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Defenseof the body by phagocytosis of cellular remians, degraded intercellular substances and foreign particles. Most common in loose connective tissue.
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Describe loose connective tissue.
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CT that provides a flexible layer next to dense CT and is found b/w more rigid structures. Lots of fibroblasts and macrophages. Amounts of ground substance and fibers is equal. Examples- hypodermis and mesenteries.
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Describe dense CT.
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Same elements as loose CT, but with higher proportion of fibers and lower proportion of cells and little ground substance.
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What's the diff b/w regular and irregular dense CT?
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Irregular has random arrangement of fibers, well suited to resist stress (found in dermis of skin, submucousa of gut, capsules and septae. Regular has parallel arrangement of fibers suited to tension and is found in ligaments and tendons.
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What is embryonic CT?
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CT found only in embryo and umbilical cord, it is composed of mesenchymal celss in a loose, watery, ECM. Also called Wharton's jelly.
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What is fascia?
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A sheet of dense CT surrounding the body beneath the skin that encloses bones, muscles, and organs.
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Name the functions of connective tissue.
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connection, support, protection, defense, force transduction, storage and diffusion.
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What are parenchyma cells?
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specific functional cells of an organ, usually derived from epithelium.
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What holds together parts of the intestine?
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Mesentery cells.
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What are the main parts of ECM?
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ground substance and fibers.
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What are the main parts of CT?
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cells and ECM.
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What are gags?
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repeating dissacharide strand, holds water in tissue
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What are adhesion proteins?
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multiadhesive, modular glycoproteins fibronectin, laminin, osteonectin, etc., that bind to cells (integrins), collagen and proteoglycan together.
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What are resident cells?
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Fibroblasts- make ECM and migrate to injury site and adipose cells for storage,
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What are transient cells?
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Macrophages, Mast cells and plasma cell that are specialized to go to a locaton and then become permamnent resident and differentiate into new cell. Also, circulating white blood cells to kill and eat invaders.
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