Epithelial and Connective TissuesEpithelial tissues

ClassesJunctions Glands

Connective TissuesMatrixCellsTypes

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

4 Types of Tissue

1)Epithelium

2)Connective

3)Muscle

4)Nervous

Human Anatomy, Larry M. Frolich, Ph.D.

Tissues: groups of cells closely associated that have a similar structure and perform a related function

• Four types of tissue– Epithelial = covering– Connective = support– Muscle = movement– Nervous = control

• Most organs contain all 4 types• Connective tissue has non-living

extra-cellular material (matrix) between its cells

EPITHELIAL TISSUESSheets of cellsSpecialized contacts/cell junctions (see below) Basal lamina: protein scaffolding secreted by

epithelial cellsBasement membrane: reticular fibers

(crossed collagen network) that supports epithelium--really associated connective tissue

Connective tissue supportNutrients from capillaries in underlying

connective tissueNerves pass throughEasily regeneratesE.g. skin, lining of gut, mucous membranes

Human Anatomy, Larry M. Frolich, Ph.D.

Classes of EpitheliaSimple: just

one layer or cell shape

Stratified: multiple layers and cell shapes

Human Anatomy, Larry M. Frolich, Ph.D.

Simple EpitheliaType Cell shape Example

Squamous Squashed Endothelium (lines bloodvessels), mesothelium(serous lining of ce lom)

Cuboidal Cubed Walls of glands

Columnar Columns Lining of gut tube;sometimes with cilia likelining of uterine tube

Pseudo-stratified Flat ce lls give riseto columns

With cilia in respiratorytubes to movemucous/particles out oflungs

Human Anatomy, Larry M. Frolich, Ph.D.

Stratified EpitheliaSquamous

E.g. epidermis

Transitional epitheliumE.g. urinary

structures--bladderStretches from 6

cells to 3 cells thick as bladder fills and expands

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

Cell JunctionsDesmosome: binding spots between cells

with proteins called cadherinsTight junctions: impermeable

E.g. gut tube, doesn’t let enzymes from gut into blood stream

Gap junctions: tubes that let small molecules pass between cells

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

Features of Apical Surface of Epithelium

Microvilli: (ex) in small intestine

Finger-like extensions of the plasma membrane of apical epithelial cell

Increase surface area for absorptionCilia: (ex) respiratory tubes

Whip-like, motile extensions Moves mucus, etc. over epithelial surface

1-way Flagella: (ex) spermatoza

Extra long cilia Moves cell

Human Anatomy, Larry M. Frolich, Ph.D.

Features of Lateral Surface of Epithelium

• Cells are connected to neighboring cells via:– Proteins-link cells together, interdigitate– Contour of cells-wavy contour fits together– Cell Junctions

• Desmosomes-adhesive spots on lateral sides• Tight Junctions-at apical area, plasma membrane

of adjacent cells fuse, nothing passes• Gap junction-spot-like junction occurring

anywhere, lets small molecules pass

Human Anatomy, Larry M. Frolich, Ph.D.

Features of the Basal Surface of Epithelium

• Basal lamina: supportive sheet between epithelium and underlying connective tissue– Selective filter

• Basement membrane = basal lamina plus underlying reticular fiber layer– Attaches epithelium to connective tissue below

• Sometimes the two are used interchangeably

Human Anatomy, Larry M. Frolich, Ph.D.

Name that Epithelial Feature!

(name and location on cell)

• Cilia• Tight

junction• Microvilli• Basement

membrane

2

3

4

1

3

1

2

4

Human Anatomy, Larry M. Frolich, Ph.D.

Glands: epithelial cells that make and secrete a water-based

substance• Exocrine Glands

– Secrete substance onto body surface or into body cavity

– Have ducts– E.G., salivary, mammary,

pancreas, liver

• Endocrine Glands– Secrete product into blood stream– Either stored in secretory cells or in

follicle surrounded by secretory cells

– Hormones travel to target organ to increase response

– No ducts

CONNECTIVE TISSUES“Areolar tissue” as modelUniversal in bodyUnderlies epithelium, supports capillaries,

small nn.Always originates from mesenchymeCELLS in MATRIX

Human Anatomy, Larry M. Frolich, Ph.D.

Extracellular matrixFibers

Collagen gives structureReticular fibers (crossed collagen) gives orderElastin gives elasticity

Ground substanceJelly-like material made of sugar-protein

molecules (proteoglycans)

Human Anatomy, Larry M. Frolich, Ph.D.

Cells of Connective TissuesFibroblasts make fibersImmune cells in areolar tissue

MacrophagesPlasma cellsMast cellsNeutrophils, Lymphocytes

Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D.

“Loose” connective tissuesAdipose tissue mostly under skin and in

mesenteriesReticular: organized 3-D network of fibers

that support lots of cellsE.g. marrow, spleen, lymph nodes

Human Anatomy, Larry M. Frolich, Ph.D.

“Dense” Connective tissuesIrregular

Thick fibers running in many planesE.g. dermis, fibrous capsules around organs

RegularAligned parallel fibersResists tensionE.g. tendon, ligaments, aponeurosesSometimes with elastic fibers (e.g.

ligamentum nuchae)

Human Anatomy, Larry M. Frolich, Ph.D.

Other Connective TissuesBoneCartilageBlood

Human Anatomy, Larry M. Frolich, Ph.D.