Connective Tissue – General/Blood Flashcards Preview

Histology > Connective Tissue – General/Blood > Flashcards

Flashcards in Connective Tissue – General/Blood Deck (46):
1

General characteristics of connective tissues

Few cells, large amounts of extracellular matrix, provides structural support, stores metabolites, defense/protection of the body (immunity, inflammatory, allergic reactions), repairs other tissues

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Collagen characteristics

Most abundant protein in the body; flexible/tensile strength; produced by fibroblasts

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Collagen type I

Can form collagen bundles; found in [dermis, tendons, ligaments, fascia, bone, most connective tissue]

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Collagen type II

found in cartilage

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Collagen type III

Assemble into reticular fibers

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Collagen types IV

Sheet like mesh-work that is found in the basal lamina

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Reticular fibers

Made of type III collagen, cross-link to form reticular tissue

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Elastic fibers

Made of elastin and fibrillin, responds to stretch/distention

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Elastin

hydrophobic domain, cross-linked by covalent bonds, fibers have variable lengths OR lamellar layers (like in blood vessels)

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Fibrillin

Thin microfibrils that surrounds developing elastic fibers

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Hyaluronic acids

Do not attach to protein cores to form proteoglycans, but will attach to existing proteoglycans to create a hydrophilic aggregate

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Role of proteoglycans

Forms aggregates with hyaluronic acids to create a "gel" that resists compression without losing compressibility

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Multiadhesive glycoproteins

Cross-links collagen, ECM, and cells; stabilizes/binds ECM to transmembrane integrins; BINDING SITES

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2 types of multiadhesive glycoproteins

Fibronectin and Laminin

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Fibronectin

Most abundant glycoprotein, contains binding sites for ECM molecules

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Laminin

Present in the basal membrane, contains binding sites

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Types of resident cells

Fibroblasts, Adipocytes, Macrophages, Mast Cells

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Fibroblasts

Principle type of resident cell, produce components of the ECM, Types: active, inactive, myofibroblasts, mesenchymal

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Active fibroblasts

Abundant cytoplasm/RER/Golgi and has euchromatic nucleoli, commonly in loose connective tissue

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Inactive fibroblasts

Limited cytoplasm, heterochromatic, common in dense connective tissue

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Myofibroblasts

Have the ability to contract, are commonly found in wound sites

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Mesenchymal fibroblasts

present in embryonic connective tissue, give rise to many types of connective tissue

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Adipocytes

Store energy as fat, produce hormones; Types: unilocular, multilocular

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Unilocular adipocytes

Most common type, forms white adipose tissue, usually large lipid droplet with a flattened nucleus

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Mulitlocular adipocytes

Rare in adults, multiple fat droplets and a large amount of mitochondria, generates heat, aka brown adipose tissue

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Macrophages

Phagocytic cells derived from monocytes, have a kidney-shaped nucleus – functions: phagocytosis of bacteria/senescent cells/cell debris, presents antigens to immune cells, produces cytokines to active the immune system

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Mast cells structure

Largest cells in connective tissue, oval w/ centrally placed nucleus, many big basophilic granules, surface contains IgE receptors

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Mast Cell Functions

Mediates Inflammatory/hypersensitivity reactions: activates during first exposure to antigen, IgE activation causes degranulation of mast cells

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Effects of histamines

Vasodilation, increase in vascular permeability, bronchoconstriction, increase in mucous production

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Types of transient cells

Plasma cells, Leukocytes

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Plasma cells

Antibody producing cells derived from B-lymphocytes, most numerous in areas of inflammation, have a "clock-face" pattern

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Types of Leukocytes

aka WBCs, Lymphocytes, monocytes, neutrophils, eosinophils, basophils [Everyone's Blood Needs More Leukocytes]

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Lymphocytes

Round, dark heterochromatic
Produce antibodies/regulate immune response

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Monocytes

Kidney shaped nucleus (is a macrophage when enters tissue), phagocytic cell

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Neutrophils

phagocytes for bacteria
elongated, segmented, multi-lobed nucleus

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Eosinophils

React to parasitic infections
Intense staining granules and bi-lobed nucleus

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Basophils

Rare cells that are involved with allergic response
Bi-lobed nucleus and basophilic granules

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Embryonic connective tissue

Mesenchyme and Mucous connective tissue

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Mesenchyme tissue

Forms a 3D network, abundant in ground substance, but has few collagen/reticular fibers

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Mucous connective tissue

Found only in umbilical cord (aka Wharton's jelly)
large amounts of hyaluronic acid

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Loose connective tissue

Highly cellular, thin/relatively sparse collagen type I fibers, abundant ground substance, large amounts of transient cells, acts as a filter tissue

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Dense connective tissue

Lots of collagen type I fibers, little ground substance

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Dense regular connective tissue

Densely packed collagen bundles, oriented in the same direction, have many inactive fibroblasts

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Dense irregular connective tissue

Collagen bundles are in different directions, fibroblast are mostly inactive, resists stress in all direction

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Specialized connective tissue

Adipose, reticular, cartilage, bone

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Reticular tissue

loose connective tissue found in the stroma of organs
Has thin, branching, interconnected threads