Overview of TissuesOverview of Tissues

Learning ObjectivesIdentify the four primary tissuesCompare and contrast primary tissue structure and function Identify examples of epithelial and connective tissue and where they are locatedCompare and contrast the structure and function of epithelial and connective tissue typesIdentify the three types of epithelial membranes

HistologyHistology

The science that deals with the The science that deals with the study of tissues.study of tissues.

Hist –Hist – tissue tissue ologyology – – study ofstudy of

Types of TissueTypes of Tissue

EpithelialEpithelial ConnectiveConnective MuscleMuscle NervousNervous

Overview of Epithelial Overview of Epithelial TissueTissue

Covering and Lining EpitheliumCovering and Lining Epithelium Covers body surfacesCovers body surfaces Lines body cavities, hollow organs Lines body cavities, hollow organs

and ductsand ductsGlandularGlandular Forms glandsForms glands

Epi – Epi – on top on top thelium - thelium - coveringcovering

General Features of General Features of EpitheliumEpithelium Consists of packed cells with little Consists of packed cells with little

extracellular material between themextracellular material between them Cells are arranged in continuous sheets, Cells are arranged in continuous sheets,

in either single or multiple layersin either single or multiple layers Have a free surface and a basal surfaceHave a free surface and a basal surface

– Lumen – the hollow space in an organ or tubeLumen – the hollow space in an organ or tube Are Are avascular : a- avascular : a- without without vascular-vascular-

blood vesselsblood vessels Have nerve supplyHave nerve supply High capacity for renewal by cell divisionHigh capacity for renewal by cell division

Functions of Functions of EpitheliumEpithelium ProtectionProtection SecretionSecretion AbsorptionAbsorption ExcretionExcretion Sensory receptionSensory reception Generation of gametesGeneration of gametes

Types of Epithelial Tissue

Covering and Lining Covering and Lining EpitheliumEpithelium

Classification by shapeClassification by shape Squamous - flatSquamous - flat Cuboidal – cubes or hexagonsCuboidal – cubes or hexagons Columnar – tall, rectangular and Columnar – tall, rectangular and

cylindricalcylindrical Transitional – range in shape from Transitional – range in shape from

flat to columnar and often change flat to columnar and often change shapeshape

Classification by Arrangement of LayersClassification by Arrangement of Layers Simple – single layer in areas of diffusion, Simple – single layer in areas of diffusion,

osmosis, filtration, secretion and osmosis, filtration, secretion and absorptionabsorption

Stratified – two or more layers used for Stratified – two or more layers used for protecting underlying tissuesprotecting underlying tissues

Pseudostratified columnar – contains one Pseudostratified columnar – contains one layer, appears to have several layers but layer, appears to have several layers but not all cells reach the surface, ciliated or not all cells reach the surface, ciliated or secrete mucoussecrete mucous

Simple Squamous Simple Squamous EpitheliumEpithelium

Single layer, flat cells, central nucleusSingle layer, flat cells, central nucleus

Lines the heart, blood vessels, lymphatic Lines the heart, blood vessels, lymphatic vessels, alveoli, glomerular capsules, and vessels, alveoli, glomerular capsules, and

forms the epithelial layer of serous membranesforms the epithelial layer of serous membranes

Function: filtration, diffusion, osmosis, Function: filtration, diffusion, osmosis, secretion in serous membranessecretion in serous membranes

Simple Cuboidal EpitheliumSimple Cuboidal Epithelium

Single layer, cube shaped, central nucleusSingle layer, cube shaped, central nucleus

Lines the tubes and smaller ducts of the Lines the tubes and smaller ducts of the kidneyskidneys

Function: secretion and absorptionFunction: secretion and absorption

Noncilialted Simple Columnar Noncilialted Simple Columnar EpitheliumEpithelium

Single layer, nonciliated, rectangular, cylindrical Single layer, nonciliated, rectangular, cylindrical cells, nucleus at base, contain goblet cells, some cells, nucleus at base, contain goblet cells, some have microvillihave microvilli

Goblet cells make and secrete mucusGoblet cells make and secrete mucus

Lines GI, respiratory, reproductive and urinary Lines GI, respiratory, reproductive and urinary tractstracts

Function: secretion and absorptionFunction: secretion and absorption

Ciliated Simple Columnar EpitheliumCiliated Simple Columnar Epithelium

Single layer, ciliated, rectangular, cylindrical cells, Single layer, ciliated, rectangular, cylindrical cells, nucleus at base, some goblet cellsnucleus at base, some goblet cells

Lines portions of trachea and upper respiratory tract, Lines portions of trachea and upper respiratory tract, Fallopian tubes, uterus, some paranasal sinuses Fallopian tubes, uterus, some paranasal sinuses and central canal of the spinal cordand central canal of the spinal cord

Function: moves mucus and other substances Function: moves mucus and other substances

Stratified Squamous EpitheliumStratified Squamous Epithelium

Several layers, cuboidal or columnar deep, Several layers, cuboidal or columnar deep, squamous superficial, basal cells replace squamous superficial, basal cells replace surface cellssurface cells

Keratinized epidermis, nonkeratinized lines Keratinized epidermis, nonkeratinized lines the mouth, esophagus, vagina and tonguethe mouth, esophagus, vagina and tongue

Function: protectionFunction: protection

Stratified Cuboidal EpitheliumStratified Cuboidal Epithelium

Two or more layers, superficial cells cube-Two or more layers, superficial cells cube-shapedshaped

Ducts of adult sweat glands and part of male Ducts of adult sweat glands and part of male urethraurethra

Function: protection and limited secretion and Function: protection and limited secretion and absorptionabsorption

Stratified Columnar EpitheliumStratified Columnar Epithelium

Several layers, irregularly shaped cells, Several layers, irregularly shaped cells, columnar cells superficialcolumnar cells superficial

Lines part of urethra and large excretory ductsLines part of urethra and large excretory ducts

Function: protection and secretionFunction: protection and secretion

Transitional EpitheliumTransitional Epithelium

Variable cell shapes, superficial cells Variable cell shapes, superficial cells squamous when stretched, cuboidal when squamous when stretched, cuboidal when relaxedrelaxed

Lines urinary bladder and portions of ureters Lines urinary bladder and portions of ureters and urethraand urethra

Function: permits organs to stretch without Function: permits organs to stretch without rupturingrupturing

Pseudostratified Columnar Pseudostratified Columnar EpitheliumEpithelium

Not true stratified tissue, cells at different Not true stratified tissue, cells at different layers, all cells attached to basement layers, all cells attached to basement membrane, only some reach surfacemembrane, only some reach surface

Ciliated lines airways of most of the upper Ciliated lines airways of most of the upper respiratory tract (trachea)respiratory tract (trachea)

Function: secretion and movement of mucusFunction: secretion and movement of mucus

Glandular EpitheliumGlandular Epithelium

Endocrine –Endocrine – ductless glands ductless glands

Pituitary, thyroid, and adrenal glandsPituitary, thyroid, and adrenal glands

Exocrine –Exocrine – glands with ducts glands with ducts

Sweat and salivary glandsSweat and salivary glands

Connective TissueConnective Tissue

General FeaturesGeneral Features Two basic elements: cells and a matrixTwo basic elements: cells and a matrix Does not occur on body surfacesDoes not occur on body surfaces Has a nerve supply, except cartilageHas a nerve supply, except cartilage Usually highly vascular except cartilage Usually highly vascular except cartilage

(avascular) and tendons(avascular) and tendons Various tissue types confer a variety of functionsVarious tissue types confer a variety of functions

Two Major TypesTwo Major Types Embryonic – found in the embryo and fetusEmbryonic – found in the embryo and fetus Mature – present in newborns to adultsMature – present in newborns to adults

Connective Tissue CellsConnective Tissue Cells

FibroblastsFibroblasts MacrophagesMacrophages Plasma CellsPlasma Cells Mast CellsMast Cells AdipocytesAdipocytes LeukocytesLeukocytes

Connective Tissue Matrix

Ground substance

Fibers

Connective Tissue Fibers

Collagen

Elastic

Reticular

Embryonic Connective Tissue

Mesenchyme – tissue from which mature connective tissue will arise

Mucous Connective Tissue – found primarily in the umbilical cord of the fetus

Mature Connective Tissue

Loose Connective Tissue Dense Connective Tissue Cartilage Bone Blood Lymph

Loose Connective Tissue

Areolar Connective Tissue

Adipose Tissue

Reticular Connective Tissue

Areolar Connective Tissue

Fibers and several kinds of cells embedded in a semifluid ground substance

Subcutaneous layer deep to skin, superficial part of dermis, mucous membranes, around blood vessels, nerves and body organs

Function: strength, elasticity, and support