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HistologyHistology is the study of tissues. As a massage therapist you might

be asking yourself, “Why is it important form me to understand thestructure and function of tissues?” You might think that the only tissuethat is important for you to know about is muscle tissue. While it isimportant to understand the structure and function of muscle tissue, thefact is, connective tissues and nervous tissue are more greatly impactedby massage work than is muscle tissue. Having a strong understandingof tissue structure and function is very important to the good massagetherapist. For example, if you are massaging a person with significantedema (swelling) what should be your concerns? Where is this fluidbuildup occurring and why? As you begin to learn about the structure oftissues, the functional aspects of these tissues will become much clearerand more apparent. One of the most important tissues, of which themassage therapist should have a strong knowledge, is the collagenousconnective tissue family. This is the principal building material of theskin, fascia, ligaments, tendons, joint capsules, and believe it or not,muscles. In this chapter, you will begin to establish a strong foundationknowledge of tissues, which you will continue to build upon throughoutthe course.

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Introduction to TissuesFour principal tissues

Epitheliumepi = upon + thele = nipple

General structure and functionTightly packed cells functioning as covering and lining tissues

General distributionAlways found as a surface tissues

Connective tissue

General structure and functionFew cells with lots of extracellular material; many functions

General distributionWide distribution — bone, tendon, fat, blood, cartilage

Muscle

General structure and functionElongated cells specialized to shorten

General distributionThe skeletal muscles of the body and many body organs

Nervous tissue

General structure and functionWirelike cells specialized for conduction of electrical signals

General distributionBrain, spinal cord, and nerves

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Epithelial TissuesClassification and Function

Classification of epithelial tissuesCell shape

Squamous (Flat)squama = scale

Cuboidalcubus = a cube + eidos = shape

Columnar

Number of layersSimple

Stratified

Functions of epithelial tissuesExchange surfaces

Secretion

Absorption

Excretion

Protection

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Epithelial TissuesStructure, Distribution, and Function

Simple Epithelial TissuesStructure

Thin lining and covering layers

Relationship to connective tissue blood vessels

Distribution

Functions

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Simple EpitheliaSimple squamous epithelium

This tissue consists of a single layer of flat cells having avery smooth appearance when viewed with the unaidedeye. It is primarily found in two major locationsthroughout the body. It forms the inner lining of thecardiovascular system, lining blood vessels, thechambers of the heart, and lymphatic vessels. Therefore,it is the tissue that the blood is always in contact with asit moves through the body. A second area it is commonlyfound is lining the cavities that house the heart, lungs,and abdominal organs. In addition, the outside of theseorgans is covered with this simple epithelium. These arethe two major areas of distribution for this tissue.Additionally, it is found in the walls of the smallest airspaces of the lungs, forming the walls of some smallurinary tubes within the kidney.

Simple cuboidal epitheliumThis tissue is a single layer of polygonal cubed cells. It isoften referred to as glandular epithelium because of itsprominent distribution in the lining of many glands ofthe body.

Simple columnar epitheliumThis tissue consists of a single layer of tall columnarshaped cells. In some locations within the body thesurface of the cells is covered with small hairlikeprocesses termed cilia. The major site of distribution ofthis tissue in the body is the inner lining surface of thedigestive tract from the beginning of the stomach to theanus. Throughout this location it has no cilia. It is foundas a cilia covered surface lining the bronchi of the lungsand the uterine tubes.

Pseudostratified columnar epitheliumThis is an interesting tissue that fooled anatomists untilthe resolution of microscopes had evolved considerably.It is a simple epithelium but, as its name suggests, itlooks stratified. All the cells attach to the basal lamina,but they do not all reach the surface. This gives the tissuethe appearance of having cells stacked in multiple layers.This is the tissue forming the inside lining of the upperrespiratory tract. In these areas the surface is coveredwith cilia.

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Stratified Epithelial TissuesStructureThick lining and covering layers

Relationship to connective tissue blood vessels

Distribution

Functions

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Stratified squamous epitheliumThis tissue, comprised of many cell layers, is the thickestepithelial tissue in the body. The bottom layer of cellshave a cuboidal shape but as the cells progress towardsthe surface they become thin and flat. It is the many flatlayers of surface cells from which the tissue derives itsname. This thick protective layer of cells forms thecovering of the body called the epidermis. It can also befound lining the inside of the mouth and nose, lining theesophagus and anus, and covering the surface of the eye.

Stratified columnar epitheliumThis is not a very common tissue in the body. It is foundin a few isolated places and has no general area ofdistribution. For example, it can be found in certainregions of the larynx (voice box) and pharynx (throat) aswell as lining the large excretory ducts of some glands.

Transitional (stratified cuboidal) epitheliumStudy of this tissue by the early anatomists revealed thatthe structure of the tissue appeared to undergo changes.Sometimes the cells looked more cuboid andmultilayered, while other times the tissue appearedthinner. This resulted from the stretching or distension ofthe tissue at its site of distribution — the lining of theurinary system. Because of its distribution as a lining ofthe urinary system from the large urinary tubules of thekidney through the ureter, bladder, and urethra, thistissue is often referred to as urinary epithelium.

Stratified Epithelia

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Overview of Connective TissuesFour basic types

General structureExtracellular material forms greater percentage of tissue than cells

FunctionsVaried functions usually related to the extracellular material

Connective tissue properSoft connective tissue

CartilageFirm to rubbery connective tissue

BoneHard connective tissue

BloodFluid connective tissue

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Connective Tissue ProperBuilding Blocks

Cells — first building blockFixed cellsFibrocyte [Fibroblasts] fibra = fiber + –cyto = cell

Cells that produce extracellular fibers

Adipose cellsadeps, adip = fat

Cells specialized to store lipid energy reserves

Wandering cellsBody defense and repair cells of the white blood cell lineage

Macrophage

Mast Cell

Lymphocyte

Plasma Cell

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Connective Tissue ProperBuilding Blocks

Extracellular matrix — second basic building blockInterfibrillar substanceWater with various suspended molecules between the fibers

FibersCollagen fiberskolla = glue + genere = to bear, carry

String-like proteins

Great tensile strength

Importance in connective tissue

Relevance to massage therapy

Elastic fibers

String-like or sheetlike branched proteins

Stretchability

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Connective Tissue ProperFunction and Classification

General functions of connective tissue proper

Classification of connective tissue properNamed after the most prominent feature of the tissue and thearrangement of that feature in the tissue.

Collagenous fibersLoose mesh of collagen

Dense mesh of collagenDense irregular meshes

Dense regular bands

Elastic fibers

Adipose cells

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Connective Tissue ProperStructure, Distribution, and Function

Collagenous connective tissuesLoose collagenous connective tissue

Structure

Distribution

Function

Dense irregular collagenous connective tissueStructure

Distribution

Function

Dense regular collagenous connective tissueStructure

Distribution

Function

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Elastic tissueStructure

Distribution

Function

Adipose tissueStructure

Distribution

Function

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CartilageBuilding Blocks and Classification

IntroductionLacks internal blood supply

Important skeletal and joint tissue

Building blocksCellsChondrocyteschondros = cartilage + –cyto = cell

Extracellular matrixInterfibrillar substance

Proteoglycans

FibersCollagen

Elastic

ClassificationCollagen fibers

Few fibers = hyaline cartilage

Many fibers = fibrocartilage

Elastic fibers

Elastic fibers = elastic cartilage

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Anatomists designate three forms of cartilage, againbased on the type and distribution of fiber in the groundsubstance. The three forms are hyaline cartilage (fewercollagen fibers), fibrocartilage (many collagen fibers), andelastic cartilage (elastic fibers).

Hyaline Cartilagehyalos = glasslike + cartilago = gristle

Hyaline cartilage is the most common cartilage in thebody, and all other cartilages are a modification of thiscartilage type. It consists of thin meshworks of collagenin a rubbery substrate. Hyaline cartilage forms themajority of the embryonic skeleton and after birth itpersists as the skeleton of the external nose, anterior endsof the ribs, in the walls of the upper respiratorypassageways, and as growth plates in the long bones.

Elastic cartilageElastic cartilage does not occur in many placesthroughout the body. As its name implies, it differs fromhyaline cartilage because as a result of the thickmeshworks of elastic fibers present in its matrix. Thishighly elastic tissue forms ths skeleton of the epiglottis(the flap-like door that covers the respiratorypassageways when you swallow) and the skeleton of theexternal ear.

FibrocartilageFibrocartilage receives its name from the large number ofthick collagen fibers that are densely distributed in therubbery matrix. The fibers are so densely packed in thetissue that there is little evidence of the surroundingmatrix. Fibrocartilage forms the strong intervertebraldiscs that separate the vertebrae. They also form articulardiscs, such as the menisci of the knee joint. These strongcartilages function as effective shock absorbers betweenbones.

Types of Cartilage

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