TissuesTissues

Types of Tissues in the BodyTypes of Tissues in the Body

TissuesTissues

Histology is the study of tissuesHistology is the study of tissues Tissues are groups of specialized cells with Tissues are groups of specialized cells with

limited number of functionslimited number of functions There are 4 PRIMARY types of tissues in There are 4 PRIMARY types of tissues in

the human bodythe human body Epithelial tissueEpithelial tissue Connective tissueConnective tissue Muscle tissueMuscle tissue Nervous tissueNervous tissue

Epithelial tissueEpithelial tissue

Epi- means uponEpi- means upon Epithelial tissue covers all exposed Epithelial tissue covers all exposed

surfaces and lines body cavitiessurfaces and lines body cavities Various types of epithelial tissues Various types of epithelial tissues

each with specific functionseach with specific functions

Characteristics of Epithelial Characteristics of Epithelial TissueTissue

Tightly packed cellsTightly packed cells Polarity – epithelial cells have a “top” Polarity – epithelial cells have a “top”

and “bottom” orientation. Surface and “bottom” orientation. Surface that faces the surface of the body or that faces the surface of the body or internal space is the APICAL layerinternal space is the APICAL layer

Attachment – basement membraneAttachment – basement membrane Avascularity – no blood supplyAvascularity – no blood supply RegenerationRegeneration

Functions of Epithelial Functions of Epithelial TissueTissue

Physical protectionPhysical protection Control of permeabilityControl of permeability SensationsSensations SecretionsSecretions

Classification of epitheliaClassification of epithelia

ShapeShape Squamous = flat Squamous = flat

cellscells Cuboidal = squareCuboidal = square Columnar = tall Columnar = tall

and thinand thin

NumberNumber Simple epithelial = Simple epithelial =

one layer of cellsone layer of cells Stratified epithelial Stratified epithelial

= several layers of = several layers of cellscells

Epithelial TissueEpithelial Tissue

Epithelial TissueEpithelial Tissue

Simple Squamous Simple Squamous epitheliumepithelium

Single layer of flat cellsSingle layer of flat cells

Simple Squamous Simple Squamous EpitheliumEpithelium

Endothelial cellsEndothelial cellsSimple squamous epitheliumSimple squamous epithelium

Simple cuboidal epitheliumSimple cuboidal epithelium

Simple cuboidal epitheliaSimple cuboidal epithelia

Single layer of square cellsSingle layer of square cells

Simple columnar epitheliumSimple columnar epithelium

Simple columnar epitheliaSimple columnar epithelia

Single layer of tall thin cellsSingle layer of tall thin cells

Stratified Squamous EpitheliaStratified Squamous EpitheliaNon-keratinizedNon-keratinized

Several layers of flat cellsSeveral layers of flat cells

Stratified squamous epithelium Stratified squamous epithelium non-keratinized non-keratinized

Stratified squamous epitheliumStratified squamous epitheliumnon-keratinizednon-keratinized

Stratified Squamous EpitheliaStratified Squamous EpitheliaKeratinizedKeratinized

Several layers of flat cells with a top Several layers of flat cells with a top layer of dead keratinized cellslayer of dead keratinized cells

Transitional epitheliaTransitional epithelia

SeveralSeveral layers of cells. Apical cells layers of cells. Apical cells rounded in shape. rounded in shape.

Transitional epitheliumTransitional epithelium

Pseudostratified ciliated Pseudostratified ciliated columnar epithelia (PSCC)columnar epithelia (PSCC)

Not truly stratifiedNot truly stratified All cells touch the basement All cells touch the basement

membrane but not all reach the membrane but not all reach the surfacesurface

GlandsGlands

Epithelial tissues often have Epithelial tissues often have associated cells that produce associated cells that produce secretionssecretions

Two types of secretionTwo types of secretion ExocrineExocrine EndocrineEndocrine

Exocrine secretionExocrine secretion

Secretion onto a surface via a tube or Secretion onto a surface via a tube or DUCTDUCT

Unicellular and multicellular glandsUnicellular and multicellular glands Unicellular exocrine gland is the Unicellular exocrine gland is the

GOBLET CELLGOBLET CELL

Goblet cellGoblet cell(unicellular exocrine gland)(unicellular exocrine gland)

Secrete mucus, often found in the Secrete mucus, often found in the gut and lining the tracheagut and lining the trachea

Goblet cellGoblet cell

Endocrine glandsEndocrine glands

Secrete directly into the bloodSecrete directly into the blood Ductless glandsDuctless glands HormonesHormones

Gland structureGland structure

Modes of secretionModes of secretionMerocrine, apocrine, holocrineMerocrine, apocrine, holocrine

Connective TissueConnective Tissue

Second major tissue type in Second major tissue type in the bodythe body

Connective TissueConnective Tissue

Found throughout the bodyFound throughout the body NEVER exposed to the outsideNEVER exposed to the outside Three basic componentsThree basic components

Specialized cells - fibroblastsSpecialized cells - fibroblasts Extracellular protein fibersExtracellular protein fibers Ground substanceGround substance MATRIX = fibers + ground substance MATRIX = fibers + ground substance

Functions of connective Functions of connective tissuetissue

Structural frameworkStructural framework Transport of fluids and chemicalsTransport of fluids and chemicals ProtectionProtection Energy storageEnergy storage Mineral storageMineral storage ImmunityImmunity

Connective Tissue ProperConnective Tissue Proper

Two typesTwo types Loose CTLoose CT Dense CTDense CT Three types of fibersThree types of fibers

Collagen – long straight fibers, very strongCollagen – long straight fibers, very strong Reticular fibers – thinner fibers, branching Reticular fibers – thinner fibers, branching

interwoven networkinterwoven network Elastic fibers – branching, wavy fibers that Elastic fibers – branching, wavy fibers that

stretchstretch

Connective Tissue ProperConnective Tissue Proper

Loose CT

Areolar CT Adipose CT Reticular CT

Areolar CTAreolar CT

Very common CTVery common CT Open frameworkOpen framework All three types of fibersAll three types of fibers Found under the dermis of the skin, Found under the dermis of the skin,

around muscles and blood vessels.around muscles and blood vessels. Distorts without damageDistorts without damage

Areolar CTAreolar CT

Areolar CTAreolar CT

Adipose CTAdipose CT

Adipocytes are the dominant cell Adipocytes are the dominant cell typetype

Collagen fibers presentCollagen fibers present Found under the skin and around Found under the skin and around

organsorgans Protection and energy storageProtection and energy storage

Adipose CTAdipose CT

Reticular CTReticular CT

Open frame work Open frame work tissue tissue

Composed Composed primarily of primarily of reticular fibersreticular fibers

Structure of liver Structure of liver and spleenand spleen

Dense CTDense CT

Tissue is composed mostly of Tissue is composed mostly of collagen fiberscollagen fibers

Types of dense CTTypes of dense CT Dense regular CTDense regular CT Elastic CTElastic CT Dense irregular CTDense irregular CT

Dense Regular CTDense Regular CT

Tightly packed collagen fibers Tightly packed collagen fibers running parallel to each otherrunning parallel to each other

Very strong tissueVery strong tissue Fibroblasts presentFibroblasts present Tendons and ligamentsTendons and ligaments

Dense Regular CTDense Regular CT

Dense Regular CTDense Regular CT

Dense Irregular CTDense Irregular CT

Collagen fibers in less organized fabricCollagen fibers in less organized fabric Meshwork, no consistent patternMeshwork, no consistent pattern More elasticMore elastic Strength to areas of the body that are Strength to areas of the body that are

stressed from many directionsstressed from many directions Found in the dermis of the skin and Found in the dermis of the skin and

around many organsaround many organs

Dense Irregular CTDense Irregular CT

Elastic CTElastic CT

Type of dense regular CTType of dense regular CT Composed mostly of elastic fibersComposed mostly of elastic fibers Allows for stretchAllows for stretch Found between the vertebrae and Found between the vertebrae and

walls of large blood vesselswalls of large blood vessels

Elastic CTElastic CT

Supportive CTSupportive CT

CartilageCartilage Strong frame work for supportStrong frame work for support Matrix contains numerous fibersMatrix contains numerous fibers Three typesThree types

HyalineHyaline ElasticElastic Fibrocartilage (Fibrous cartilage)Fibrocartilage (Fibrous cartilage)

Hyaline cartilageHyaline cartilage

Most commonMost common Matrix of collagen fibersMatrix of collagen fibers Chondrocytes = Chondrocytes =

cartilage cellscartilage cells Lacuna = chamber Lacuna = chamber

around the cartilage around the cartilage cellcell

Perichondrium presentPerichondrium present LocationsLocations

End of long bonesEnd of long bones Tracheal ringsTracheal rings Costal cartilageCostal cartilage

Perichondrium of hyaline Perichondrium of hyaline cartilagecartilage

Elastic cartilageElastic cartilage

Contains elastic Contains elastic fibers in the matrix fibers in the matrix for stretchfor stretch

Found in the pinna Found in the pinna of the ear, and of the ear, and epiglottisepiglottis

Perichondrium Perichondrium presentpresent

Fibrocartilage (Fibrous Fibrocartilage (Fibrous cartilage)cartilage)

Matrix of collagen Matrix of collagen fibersfibers

Densely woven fibersDensely woven fibers Very tough and Very tough and

durabledurable No perichondriumNo perichondrium Found:Found:

Intervertebral discsIntervertebral discs Meniscus of the kneeMeniscus of the knee Pubic symphysisPubic symphysis

FibrocartilageFibrocartilage

BoneBone

Type of supportive CTType of supportive CT Bone cells are osteocytesBone cells are osteocytes Bone forming cells are osteoblastsBone forming cells are osteoblasts Matrix is mineralized collagen fibersMatrix is mineralized collagen fibers

BoneBone

Fluid CTFluid CT

BloodBlood LymphLymph

MembranesMembranes

Combination of epithelial tissues and CTCombination of epithelial tissues and CT Consists of epithelial sheet and underlying Consists of epithelial sheet and underlying

CTCT Membranes cover and protect Membranes cover and protect Four typesFour types

Mucous membranesMucous membranes Serous membranesSerous membranes Cutaneous membraneCutaneous membrane Synovial membraneSynovial membrane

Mucous membranesMucous membranes

Line passageways that communicate Line passageways that communicate with the outsidewith the outside Digestive, respiratory, reproductive, Digestive, respiratory, reproductive,

urinary tractsurinary tracts Important barriers to prevent entry Important barriers to prevent entry

of pathogensof pathogens Usually a simple epithelial lining but Usually a simple epithelial lining but

NOT alwaysNOT always

Serous membranesSerous membranes

These membranes line the subdivisions of These membranes line the subdivisions of the ventral body cavitythe ventral body cavity

Simple squamous epithelial (mesothelium) Simple squamous epithelial (mesothelium) and areolar CTand areolar CT

Very thin and attached to the body wall Very thin and attached to the body wall and organs coveredand organs covered PleuraPleura PeritoneumPeritoneum Pericardial Pericardial

Cutaneous membraneCutaneous membrane

SkinSkin Covers the surface of the bodyCovers the surface of the body Keratinized stratified squamous Keratinized stratified squamous

epithelial and underlying CT epithelial and underlying CT

MembranesMembranes

Other Tissue TypesOther Tissue Types

Muscles tissueMuscles tissue Skeletal muscleSkeletal muscle Cardiac muscleCardiac muscle Smooth muscleSmooth muscle

Nervous TissueNervous Tissue

Skeletal muscleSkeletal muscle

Cardiac muscleCardiac muscle

Smooth muscleSmooth muscle

Nervous tissueNervous tissue

Nervous TissueNervous Tissue