Connective Tissue

Connective tissue

Supports and binds together other structural elements throughout the body; made up of cells and fibers embedded in a gel-like extracellular matrix

Ground substance

Occupies all of space between cells and fibers of CT; colorless, transluscent substance with consistency of highly hydrated gel

Glycosaminoglycans

Major components of ground substance

Adhesion proteins

Bind cells to fibers of CT

Fibronectin

Binding sites for cells, collagen fibers, proteoglycans

Integrins

Able to bind directly to collagen fibers

Laminin

Binding sites for cell membranes, collagen fibers, and heparin sulfate proteoglycan

Basal lamina

Laminin copolymerizes with type IV collagen and entactin to form what?

Protein fibers

Organic ground substance

Fluid

3 components of CT extracellular matrix

Protein fibers

Component of CT produced by fibroblasts

Collagen

White fibers in bundles; resist tensile force

Elastic fiber

Yellow fibers; stretch and recoil

Reticular fiber

Anchors and supports functional cells

Organic ground substance

Stuff between cells and fibers; clear, colorless, viscous fluid; can be minerals

Fluid

Cells and fibers are suspended in __

Collagen fibers

Most abundant fibrous component of CT

Hydroxyproline

Hydroxylysine

2 common amino acids to all collagen fibers

Type I, II, III

Most common types of collagen

Type I

Type of collagen synthesized from skin, bone, tendon, and capsule of organs

Type II

Type of collagen synthesized from ground substance of cartilage, nucleus pulposus, and vitreous body of eye

Type III

Type of collagen fiber synthesized from slender fibers arranged in loose network; smooth muscle cells and liver cells

Type IV

Type of collagen synthesized from copolymerization with laminin and entactin to form basal lamina

Type V to X

Type of collagen quite restricted in their distribution

Reticular fibers

Thin fibers that form networks throughout parenchyma of many organis; composed of fibrils of type II collagen and associated glycoproteins

Argyrophilic

Reticular fibers are described as __ fibers because of their black staining property with silver salts

Hematopoietic and lymphoid tissues

Reticular fibers are most abundant in what tissues?

Elastic fibers

Selectively stained with resorcin-fuschsin; composed of amorphous, rubber-like glycoprotein, elastin

Desmosine

Isodesmosine

Polymers of elastin cross-linked by covalent bond between 2 uncommon amino acids

Fibroblast

Elastic fibers are synthesized by?

Elastic laminae

Elastic fibers are assembled in this fenestrated sheet

-blast

Produces matrix

-cyte

Mature cells that maintain the matrix

-clast

Destroys matrix

Fixed cells

They constitute stable population of relatively immobile cells

Fibroblast

Produce and maintain the extracellular components of CT

Adipose / fat cells

Store lipids after meals and later release them into blood to serve as an energy source during fasting

Macrophages

Motile phagocytic cells found in CT throughout body; participate in maintenance of CT by clearing it of dead cells, debris, and other foreign materials

Neutrophils

They gather in great number at site of infection

Pus

The __ that accumulates at sites of infection are mainly consist of dead and dying neutrophils

Eosinophils

Greatly increased in allergic conditions and parasites, such as nematode worms

Lymphocytes

Involve in protective immunosurveillance

Plasma cells

Develop by further differentation of lymphocytes that have encountered antigen and produced specific antibodies against it

Mast cells

Function as part of immune system; detects foreign proteins in tissues and rapidly releasing potent mediators

Loose

Reticular

Mucous

Dense

Types of CT

Loose CT

Type of CT of loose network of randomly oriented fibers in an abundant ground substance; most widespread of CT

Reticular CT

Type of CT in which a network of argyrophilic fibers are the dominant fibrous component; surrounds functional unit of epithelial organs

Mucous CT

Type of CT that contain large amount of ground substance, rich in hyaluronic acid; principal component of umbilical cord; formerly called Wharton’s Jelly

Irregular dense CT

Collagen make up most of its volume, the fiber bundles are relatively coarse and interwoven in compact meshwork with little space

Regular dense CT

Bundles of collagen are oriented parallel to one another and closely packed with little intervening ground substance

Cartilage

Specialized type of CT in which chondrocytes are distributed in a firm gel-like ground substance; not penetrated by blood vessels

Lacuna / lacunae

Chondrocytes are isolated in these small cavities in ground substance

Growth in length of long bones

Role of cartilage

Hyaline

Elastic

Fibrocartilage

Types of cartilage

Endochondral ossification

Chondrocytes in hyaline cartilage have the ability to replace cartilage bone through this process

Chondroitin sulfate

Keratan sulfate

Principal glycosaminoglycans of cartilage

Elastic cartilage

Cartilage found in external ear and small cartilages of larynx; yellowish color, greater flexibility due to elastic fibers

Fibrocartilage

Cartilage found in vertebral column and sites of insertion of ligaments and tendons into bone; resembles dense regular CT