ExerciseExercise 66

Classification of Classification of TissuesTissues

What is a tissue?What is a tissue?

Group of cells Group of cells Similar structure & functionSimilar structure & function

4 Major Tissue Types4 Major Tissue Types

EpithelialEpithelial Connective Connective MuscleMuscle NervousNervous

Epithelial TissuesEpithelial Tissues

Cover surfacesCover surfaces

Simple or stratified?Simple or stratified? Simple = 1 layer of cells attached to Simple = 1 layer of cells attached to

basement membranebasement membrane Stratified = 2 or more layersStratified = 2 or more layers

Named by “shape” of top layer (apical Named by “shape” of top layer (apical layer), not bottom (basal layer)layer), not bottom (basal layer)

Epithelial TissuesEpithelial Tissues

Shapes of Epithelial CellsShapes of Epithelial Cells SquamousSquamous

FlattenedFlattened CuboidalCuboidal

Cubelike Cubelike ColumnarColumnar

Column-shapedColumn-shaped

Simple squamousSimple squamous

Stratified squamousStratified squamous

Simple cuboidalSimple cuboidal

Stratified cuboidalStratified cuboidal

Simple columnarSimple columnar

Stratified columnarStratified columnar

Epithelial TissuesEpithelial Tissues

Simple squamous epitheliumSimple squamous epithelium

Epithelial TissuesEpithelial Tissues

Simple cuboidal epitheliumSimple cuboidal epithelium

Fig 4-4

Epithelial TissuesEpithelial Tissues

Simple columnar epitheliumSimple columnar epithelium

Epithelial TissuesEpithelial Tissues

Pseudostratified columnar epitheliumPseudostratified columnar epithelium Actually simple columnar: nuclei are at Actually simple columnar: nuclei are at

different levels so there appears to be different levels so there appears to be more than one layermore than one layer

Fig 4-5

Epithelial TissuesEpithelial Tissues

Stratified squamous epitheliumStratified squamous epithelium

Epithelial TissuesEpithelial Tissues

Stratified cuboidal epitheliumStratified cuboidal epithelium

Epithelial TissuesEpithelial Tissues

Stratified columnar epitheliumStratified columnar epithelium

Fig 4-5

Epithelial TissuesEpithelial Tissues

Fig 4-4

Transitional epitheliumTransitional epithelium Stratified squamous epithelium formed of Stratified squamous epithelium formed of

rounded cells that can slide over one rounded cells that can slide over one another, allowing the organ to stretch: another, allowing the organ to stretch:

urinary system onlyurinary system only

CONNECTIVE TISSUESCONNECTIVE TISSUES

Embryonic connective tissueEmbryonic connective tissue mesenchymemesenchyme

Loose connective tissueLoose connective tissue Areolar, adipose, reticularAreolar, adipose, reticular

Dense connective tissueDense connective tissue Dense irregular, dense regularDense irregular, dense regular

Supportive connective tissueSupportive connective tissue Hyaline, elastic, fibrocartilages; boneHyaline, elastic, fibrocartilages; bone

Fluid connective tissueFluid connective tissue Blood, Blood, lymphlymph

CONNECTIVE TISSUESCONNECTIVE TISSUES

Differing proportions of cells & fibers to Differing proportions of cells & fibers to “matrix”“matrix” Matrix Matrix

noncellular, nonliving material between noncellular, nonliving material between connective tissue cellsconnective tissue cells

Different proportions Different proportions strength of tissue strength of tissue

Classification of Connective Classification of Connective TissuesTissues

Fig. 4-8

Many cell types

Syrupy ground substance

Distinct cell types

Watery matrix

Less diverse cell types

More fibrous matrix

EmbryonicEmbryonic Connective Connective TissueTissue

MesenchymeMesenchyme Many star-shaped stem cells Gives rise to all other connective tissues Not present in adults

Fig. 4-10

Loose Connective Tissue: Loose Connective Tissue: AreolarAreolar

Adipose Connective Adipose Connective TissueTissue

Adipose connective tissueAdipose connective tissue (fat) Insulation for the body’s tissues Food storage Little matrix

Fig. 4-11

Reticular Connective Reticular Connective TissueTissue

Reticular connective tissueReticular connective tissue Reticular fibers form a soft internal

skeleton for support

Dense Irregular Dense Irregular Collagenous Collagenous

Connective TissueConnective Tissue

Dense Irregular Elastic Connective Tissue

Dense Regular Collagenous Dense Regular Collagenous Connective TissueConnective Tissue

Dense regular connective tissueDense regular connective tissue Fibers in one direction Tendons, ligaments of body’s joints

Fig. 4-12

Dense Regular Elastic Connective Tissue

Hyaline CartilageHyaline Cartilage Connective Tissue Connective Tissue

Elastic CartilageElastic Cartilage Connective Tissue Connective Tissue

Elastic CartilageElastic Cartilage Maintains shape, but flexible Many elastic fibers

Fibrocartilage Fibrocartilage Connective Tissue Connective Tissue

FibrocartilageFibrocartilage Strength, shock absorption Dense network of collagen fibers

Osseous Connective Osseous Connective TissueTissue

Osseous Connective Tissue (Bone)Osseous Connective Tissue (Bone) Support, protection

Blood Connective TissueBlood Connective Tissue

Lymph Connective Lymph Connective TissueTissue

LymphLymph Fluid of the lymphatic system Like plasma without the big proteins Immune defense

MUSCLE TISSUESMUSCLE TISSUES

SkeletalSkeletal CardiacCardiac SmoothSmooth

Skeletal Muscle TissueSkeletal Muscle Tissue

Cardiac Muscle TissueCardiac Muscle Tissue Only in the heartOnly in the heart Striated tissueStriated tissue Under involuntary controlUnder involuntary control Branching, uninucleate cells with Branching, uninucleate cells with

intercalated discsintercalated discs

Smooth Muscle TissueSmooth Muscle Tissue Found in the walls of hollow organs Found in the walls of hollow organs

(digestive, urinary tracts; blood vessels)(digestive, urinary tracts; blood vessels) 2 layers at right angles for

contraction/dilation of the organ cavity Not striated tissue Uninucleate, spindle-shaped cells

Muscle type Cells striations Voluntary?

Cardiac branchedUninucleateIntercalated discs

yes no

Skeletal Long fibersmultinucleate

yes yes

Smooth Spindle shaped1 nucleus

no no

NERVOUS TISSUENERVOUS TISSUE Brain, spinal cord, nervesBrain, spinal cord, nerves 2 basic cell types:2 basic cell types:

Neuroglia cells Protect, support, insulate neurons

Neurons Receive stimuli & conduct nerve impulses