6-CONNECTIVE TISSUE Flashcards by 횐호 강

CONNECTIVE TISSUE GENERAL TYPES

EMBRYONIC
ADULT

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EMBRYONIC CONNECTIVE TISSUE types

Mesenchyme
Mucous tissue

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ADULT CONNECTIVE TISSUE types

Ordinary/ Connective Tissue Proper
Specialized Connective Tissue

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Ordinary/ Connective Tissue Proper types

Loose Connective Tissue
Dense Connective tissue (regular/ irregular)

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Specialized Connective Tissue types

Cartilage
Bone
Blood
hematopoietic tissue`

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COMPONENTS OF THE CONNECTIVE TISSUE

cells
fibers
ground substance

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Major constituent of connective tissue is the

extracellular matrix (ECM)
made of: Protein fibers Ground substances

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EXTRACELLULAR MATRIX (ECM) protein fibers

collagen, reticular, and elastic fibers

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ECM Ground substance is a highly hydrophilic, viscous complex of

anionic macromolecules
Multiadhesive glycoproteins

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anionic macromolecules in ecm

(glycosaminoglycans and proteoglycans)

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Multiadhesive glycoproteins in ecm

(laminin, fibronectin, and others)

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FUNCTIONS if connective tissue

SUPPORT AND PACKAGING
STORAGE
TRANSPORT
DEFENSE
REPAIR

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connective tissue SUPPORT AND PACKAGING example

Tendons, ligaments, areolar tissue
Bone and cartilage

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connective tissue STORAGE tissue examples

Lipids are stored in ADIPOSE TISSUE

LOOSE CONNECTIVE TISSUE stores water and electrolytes

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serves as the medium through which nutrients and metabolic wastes are exchanged between cells and their nourishing blood supply

connective tissue matrix

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DEFENSE EXAMPLE OF CONNECTIVE TISSUE

▪ Related to its content of phagocytic (macrophage) and antibody producing cells (plasma cells).

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CELL TYPES in connective tissue

WANDERING OR MOBILE CELLS
FIXED CELLS

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Permanent resident population
▪ Responsible for production and maintenance of extracellular components
▪ Storage for reserve fuel (fibroblasts, fat cells, undifferentiated mesenchymal cells, reticular cells)

FIXED CELLS

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Transient emigrants from the bloodstream
▪ Concerned with the short term tissue reaction in injury

WANDERING OR MOBILE CELLS

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WANDERING OR MOBILE CELLS EXAMPLES

(neutrophils, monocytes, lymphocytes, mast cells, plasma cells, macrophages)

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Embryonic tissue where all types of connective tissues originate

MESENCHYME

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Formed by elongated undifferentiated cells that are characterized by oval nuclei with prominent nucleoli and fine chromatin

MESENCHYME

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______________ develops mainly from the middle layer of the embryo, the ________

MESENCHYME; mesoderm

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Develops into other types of structures, such as blood cells, endothelial cells, and muscle cells.

MESENCHYME

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CELLS OF CONNECTIVE TISSUE

Fibroblast ▪ Adipocytes ▪ Macrophages and the Mononuclear Phagocyte System ▪ Mast Cells ▪ Plasma Cells ▪ Leukocytes

Originate locally from undifferentiated mesenchymal cells and spend all their life in connective tissue

FIBROBLASTS

Synthesize collagen, elastin, glycosaminoglycans, proteoglycans and multiadhesive glycoproteins

FIBROBLASTS

are the most common cells in connective tissue

FIBROBLASTS

typically show large active nuclei and eosinophilic cytoplasm tapering off in both directions along the axis of the nucleus, a morphology usually called "spindle-shaped

FIBROBLASTS

Two stages of activity of fibroblasts

Active (fibroblast) Quiescent (fibrocyte)

are large cells with large, euchromatic nuclei and basophilic cytoplasm (fibroblasts)

ACTIVE FIBROBLASTS

are smaller with less prominent, heterochromatic nuclei

INACTIVE FIBROBLAST or fibrocytes

Also known as fat cells

ADIPOCYTES

Connective tissue cells that have become specialized for storage of neutral fats or for the production of heat.

ADIPOCYTES

Connective tissue cells Incapable of mitotic division

ADIPOCYTES

ADIPOCYTES Can be stained with

osmic acid

ADIPOCYTES FUNCTIONS:

Storage of neutral fats or for the production of heat key regulators of the body’s energy metabolism Shock absorbers As insulators For protecting organs in the form of soft, elastic pad For aesthetic purposes

TWO TYPES OF ADIPOSE TISSUE

White adipose tissue Brown adipose tissue

the more common type ▪ composed of cells that, when completely developed, contain one large central droplet of whitish- yellow fat in their cytoplasm

White adipose tissue

▪ Contains cells with multiple lipid droplets interspersed among abundant mitochondria, which give these cells the darker appearance. ▪ has a much more limited distribution

Brown adipose tissue

o originate from hematopoietic stem cells in bone marrow o are transient cells of most connective tissues o also originate in the bone marrow and move to the connective tissue where they reside for a few days o usually die by apoptosis

MAST CELLS, MACROPHAGES, AND PLASMA CELLS

were discovered and initially characterized by their phagocytic ability

Macrophages

Macrophages in EM are characterized by

an irregular surface with pleats, protrusions, and indentations Generally have a well-developed Golgi apparatus, many lysosomes, and rough ER

MACROPHAGES AND THE MONONUCLEAR PHAGOCYTE SYSTEM FUNCTIONS:

o Important agents of defense o Act as scavengers because of their mobility and phagocytic activity, engulfing extravasated blood cells, bacteria, foreign bodies and dead cells. o Play a fundamental role in the development of immunity

Macrophages are Referred to as ________ once the phagocytosed particle, enclosed within the invaginated cell membrane.

phagosome

o macrophages that are stimulated o change their morphological characteristics and metabolism

ACTIVATED MACROPHAGES

o has an increase in capacity for phagocytosis and intracellular digestion o exhibit enhanced metabolic and lysosomal enzyme activity

ACTIVATED MACROPHAGES

Kupffer cells location and main function

Liver Same as macrophages

Microglia cells cells location and main function

Nerve Tissue of the CNS same as macrophages

Langerhans Cell cells location and main function

Skin Antigen processing and presentation

Dentritic cells location and main function

Lymph nodes Antigen processing and presentation

Osteoclast cells location and main function

Bone (fusion of several macrophages) Digestion of bone

Multinuclear giant cells location and main function

Connective tissue (fusion of several macrophages) Segregation and digestion of foreign bodies

Placenta macrophages

Hofbauer Cells

Adipose tissue macrophages

Adipose Macrophages

Are large, oval or round connective tissue cells, 20-30 m in diameter Cytoplasm is filled with basophilic secretory granules. Spherical nucleus is centrally situated and may be obscured by the cytoplasmic granules

MAST CELLS

displayed by mast cells because of high content of acidic radicals in their sulfated glycosaminoglycans

METACHROMASIA

which means that they can change the color of some basic dyes (eg, toluidine blue) from blue to purple or red.

METACHROMASIA

A PARTIAL LIST OF IMPORTANT MOLECULES RELEASED FROM TE GRANULES INCLUDES

Heparin Histamine Serine proteases Eosinophil and neutrophil chemotactic factors Leukotrienes C4, D4, and E4 (SRS-A)

a sulfated glycosaminoglycan that acts locally as an anticoagulant

Heparin

promotes increased vascular permeability and smooth muscle contraction

Histamine

activate various mediators of inflammation

Serine proteases

attracts those leukocytes

Eosinophil and neutrophil chemotactic factor

triggers smooth muscle contraction

Leukotrienes C4, D4, and E4 (SRS-A)

mast cells near small blood vessels in skin and mesenteries

PERIVASCULAR MAST CELLS

mucosa lining digestive and respiratory tracts

MUCOSAL MAST CELLS

TYPES OF MAST CELLS

PERIVASCULAR MAST CELLS MUCOSAL MAST CELLS

are large, ovoid cells that have a basophilic cytoplasm due to their richness in rough ER

Plasma cells

Nucleus of the plasma cell is generally

spherical but eccentrically placed

Plasma cells There is alternating areas of compact, peripheral regions of heterochromatin and lighter areas of euchromatin, giving the nucleus a

clock-face appearance (Cartwheel Appearance)

Average lifespan of plasma cells

10-20 days.

migration of leukocytes from the blood vessels to the connective tissue

DIAPEDESIS-

classic signs involve redness and swelling with heat and pain (rubor et tumor cum calore et dolore).

Inflammation-

substances of various origin that induce some of the events characteristic of inflammation o Chemotactic factors

chemical mediators of inflammation

Leukocytes do not return to the blood after arriving in connective tissue except for the

lymphocytes

is responsible for the migration of large quantities of specific cell types to regions of inflammation

CHEMOTAXIS-

happens under the influence of chemotactic factors

CHEMOTAXIS-

most abundant connective fibers

COLLAGEN

COLLAGEN Various types are present in the

skin, bone, cartilage, smooth muscle, and basal lamina.

TYPES OF COLLAGEN

1. COLLAGEN THAT FORM FIBRILS 2. FIBRIL-ASSOCIATED COLLAGENS 3. COLLAGEN THAT FORMS ANCHORING FIBRILS 4. COLLAGEN THAT FORMS NETWORK

Type I collagen is the most abundant and has a widespread distribution such as

tendons, organ capsules, and dermis.

COLLAGEN THAT FORM FIBRILS TYPE I REPRESENTATIVE TISSUES AND MAIN FUNCTION

skin, tendon, bone, dentin resistance to tension

COLLAGEN THAT FORM FIBRILS TYPE II REPRESENTATIVE TISSUES AND MAIN FUNCTION

cartilage, vitreous body resistance to pressure

COLLAGEN THAT FORM FIBRILS TYPE III REPRESENTATIVE TISSUES AND MAIN FUNCTION

skin, muscle, blood vessels, frequently together with type I structural maintenance in expansible organ

COLLAGEN THAT FORM FIBRILS TYPE V REPRESENTATIVE TISSUES AND MAIN FUNCTION

fetal tissues, skin, bone, placenta, most interstitial tissue participates in type I collagen function

COLLAGEN THAT FORM FIBRILS TYPE XI REPRESENTATIVE TISSUES AND MAIN FUNCTION

cartilage participate in type II collagen functionn

short structures that bind the surfaces of collagen fibrils to one another and to other components of the ECM.

FIBRIL-ASSOCIATED COLLAGENS

FIBRIL-ASSOCIATED COLLAGENS Molecules are also known as FACIT collagens or

fibril-associated collagens with interrupted triple helices

they do not form fibril however they are associated to our collagen fibrils

FIBRIL-ASSOCIATED COLLAGENS

FIBRIL ASSOCIATED COLLAGEN TYPE IX REPRESENTATIVE TISSUES AND MAIN FUNCTION

cartilage, vitreous body bound glycosaminoglycans, associated with type II collagen

FIBRIL ASSOCIATED COLLAGEN TYPE XII REPRESENTATIVE TISSUES AND MAIN FUNCTION

Embryonic tendon and skin interacts with type I collagen

FIBRIL ASSOCIATED COLLAGEN TYPE XIV REPRESENTATIVE TISSUES AND MAIN FUNCTION

Fetal skin and tendon -

type of collagen that are present in the anchoring fibrils that bind the basal lamina to reticular fibers in the underlying connective tissue

COLLAGEN THAT FORMS ANCHORING FIBRILS

COLLAGEN THAT FORMS ANCHORING FIBRILS TYPE VII REPRESENTATIVE TISSUES AND MAIN FUNCTION

epithelia acnhors skin epidermal basal lamina to underlying stroma

molecules assemble in a meshwork that constitutes a major structural component of the basal lamina

COLLAGEN THAT FORMS NETWORK

refers to the production of the collagen

COLLAGEN SYNTHESIS-

collagens are produced by the

fibroblast

found in cartilage which also produce collagen

chondroblast-

cells found in the dental pulp

odontoblast

polypeptides initially formed on ribosomes of the rough ER

PROCOLLAGEN CHAINS

each procollagen molecule is composed of two

a1 and one a2 peptide chains, each with a molecular mass of approximately 100 kDa

present in all basement membranes, assembles as a lattice-like network in the basal lamina.

Collagen type IV,

COLLAGEN THAT FORMS ANCHORING FIBRILS TYPE IV REPRESENTATIVE TISSUES AND MAIN FUNCTION

all basement membranes support of delicate structures, filtration

order of collagen turnover rate from slowest to fastest

normal connective tissue some organs, such as tendons and ligaments periodontal ligament surrounding teeth

members of an enzyme class, matrix metalloproteinases or MMPs

COLLAGENASES

COLLAGENASES are members of an enzyme class

matrix metalloproteinases or MMPs

- specific enzymes initiating degradation of collagen - Clip collagen molecules rendering them susceptible to further degradation by nonspecific proteases

COLLAGENASES

consist mainly of collagen type III, which forms extensive networks of extremely thin (diameters 0.5-2 m) and heavily glycosylated fibers in certain organs

RETICULAR FIBERS

RETICULAR FIBERS can be easily stained black by

impregnation with silver salts

RETICULAR fibers are particularly abundant in the framework of hematopoietic organs like

spleen, lymph nodes, red bone marrow

RETICULAR FIBERS constitute a network around the parenchymal cells of various organs like

liver, endocrine glands

Very flexible and have recoiling properties o Are thinner than the average collagen o Form sparse networks interspersed with collagen bundles in many organs subject to much bending or stretching, such as the wall of large arteries

ELASTIC FIBERS

Elastic fibers or________add the resiliency to connective tissue

lamellae (sheets)

ELASTIC FIBERS are usually demonstrated using ___________ which stains elastin a ___________

aldehyde fuscin dark magenta.

are secreted by fibroblasts in connective tissue and by smooth muscle cells in the walls of blood vessels

elastin

Elastin molecules are_______ in shape with a molecular mass of

globular 70 kDa

are produced when covalent cross-links are formed among four lysine residues in different elastin molecules

DESMOSINE AND ISODESMOSINE

effectively cross-link the subunits of elastin and help account for the rubberlike qualities of this protein

DESMOSINE AND ISODESMOSINE

is resistant to digestion by most proteases

Elastin

easily hydrolyzed by pancreatic elastase

Elastin

a family of proteins related to the scaffolding necessary for the deposition of elastin - forms a core of 10-nm microfibrils in the first stage of elastic fibers development

FIBRILLIN

results from mutations in the fibrillin gene - a disease characterized by a lack of resistance in the tissues rich in elastic fibers

MARFAN SYNDROME

highly hydrated, transparent, complex mixture of macromolecules

EXTRACELLULAR MATRIX: GROUND SUBSTANCES

EXTRACELLULAR MATRIX: GROUND SUBSTANCES o principally in three classes:

o glycosaminoglycans (or GAGs) o proteoglycans o multiadhesive glycoproteins

TEM: connective tissue extracellular matrix reveals ground substance as either ________________ that fills spaces between the collagen and elastic fibers and surrounds fibroblast cells and processes

empty or containing fine granular material

linear polysaccharides formed by repeating disaccharide units usually composed

GLYCOSAMINOGLYCANS

GLYCOSAMINOGLYCANS originally called

mucopolysaccharides

2 examples of GLYCOSAMINOGLYCANS (GAGs)

o Uronic acid - Glucuronic or iduronic acid o Hexosamine - Glucosamine or galactosamine

The four main GAGs found in proteoglycans are:

o Dermatan sulfate o Chondroitin sulfates o Keratan sulfate o Heparan sulfate

are composed of a core protein to which are covalently attached various numbers and combinations of the sulfated GAGs

PROTEOGLYCANS

PROTEOGLYCANS function

anchoring cells to the matrix

cell-surface proteoglycans - are present on many types of cells, particularly epithelial cells

SYNDECAN-

one of the most important ECM proteoglycans - the dominant proteoglycan in cartilage

AGGRECAN

Several disorders have been described in which a deficiency in lysosomal enzymes causes glycosaminoglycan degradation to be blocked, with the consequent accumulation of these compounds in tissues. What are these diseases?

Hurler, Hunter, sanfilippo, and Morquio syndromes.

- Bacteria that produce ___________, an enzyme that hydrolyzes hyaluronic acid and other glycosaminoglycans - have greater invasive power because they reduce the viscosity of the connective tissue ground substance

hyaluronidase

o have a frequently branched carbohydrates moiety attached, but in contrast to proteoglycans the protein moiety usually predominates o several such glycoproteins have important roles in the adhesion of cells to their substrate o stabilizes or holds the position of each cells in the extracellular matrix

MULTIADHESIVE GLYCOPROTEINS

is an important example synthesized by fibroblasts and some epithelial cells - with a molecular mass of 22-240 kDa - has binding sites for collagens, certain GAGs, and integrins of cell membranes

FIBRONECTIN-

trimeric, a larger, cross-shaped glycoprotein - participates in the adhesion of epithelial cells to the basal lamina - has binding sites for type IV collagen, GAGs, and integrins - all basal laminae are rich in

laminin

Two general classes of connective tissue

LOOSE CONNECTIVE TISSUE DENSE IRREGULAR CONNECTIVE TISSUE

contains faint ground substance with fine fibers of collagen and is adjacent to epithelium.

LOOSE CONNECTIVE TISSUE

tissue underlies the thinner layer of loose connective tissue and is invariably much richer in larger bundles of collagen

DENSE IRREGULAR CONNECTIVE

o supports many structures which are normally under some pressure and low friction o Usually supports epithelial tissue, forms a layer around small blood and lymphatic vessels, and fills the spaces between muscle and nerve fibers

LOOSE CONNECTIVE TISSUE

LOOSE CONNECTIVE TISSUE Also found in:

- papillary layer of the dermis - hypodermis - linings of the peritoneal and pleural cavitie - in glands - in mucous membranes (wet membranes that line the hollow organs) supporting the epithelial cells.

LOOSE CONNECTIVE TISSUE Also called as

AREOLAR TISSUE

are the most numerous cells IN LOOSE CONNECTIVE TISSUE

Fibroblasts and macrophages

offers resistance and protection o has the same components found in loose connective tissue, but there are fewer cells and a clear predominance of collagen fibers over ground substance

DENSE CONNECTIVE TISSUE

DENSE IRREGULAR CONNECTIVER TISSUE o known as dense irregular connective tissue when the collagen fibers are

arranged in bundles without a definite orientation

collagen fibers form a 3-dimensional network in dense irregular tissue, providing resistance to stress from all directions o often found closely associated with loose connective tissue

DENSE IRREGULAR CONNECTIVER TISSUE

DENSE REGULAR CONNECTIVE TISSUE o collagen bundles are arranged according to a

definite pattern

collagen fibers aligned with the linear orientation of fibroblasts in response to prolonged stresses exerted in the same direction offering great resistance to traction forces

DENSE REGULAR CONNECTIVE TISSUE

are produced and enveloped by the reticular cells, forming an elaborate network through which interstitial fluid or lymph and wandering cells from blood pass continuously.

Reticular fibers of type III collagen

MUCOUS TISSUE o found mainly in the umbilical cord and fetal tissues o principal component of the umbilical cord, referred to as

Wharton's jelly

similar form of connective tissue is also found in the pulp cavity of young teeth

MUCOUS TISSUE

MUCOUS TISSUE has an abundance of ground substance composed chiefly of__________, making it a jellylike tissue containing very few collagen fibers with scattered fibroblasts

hyaluronic acid