• A group of closely associated cells that perform related functions and are similar in structure

• Between cells: nonliving extracellular material

• Four basic types of tissue…function–Epithelium…covering–Connective tissue…support–Muscle tissue…movement–Nervous tissue…control

Epithelium: sheet of cells that covers a body surface or lines a body cavity; also form most of the body’s glands

Roles: as interfaces and as boundaries Functions:

Protection AbsorptionSensory reception Ion transportSecretion Filtration

Formation of slippery surfaces for movement

CellularityCellularity Specialized contactsSpecialized contacts PolarityPolarity

Free upper (apical) surfaceFree upper (apical) surface Lower (basal) surface contributing Lower (basal) surface contributing

basal lamina to basement basal lamina to basement membrane membrane

Support by connective tissue Support by connective tissue Avascular but innervatedAvascular but innervated

Without vesselsWithout vessels With nerve endings With nerve endings

RegenerationRegeneration

• According to thickness• “simple” - one cell layer

– “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer)

• According to shape• “squamous” – wider than tall

– “cuboidal” – as tall as wide– “columnar” - taller than wide

to protect

where diffusion is important

where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements

“ciliated” literally = eyelashes(see next page)

Rare…

Stratified: regenerate from below

Rare…

EndotheliumEndothelium A simple A simple

squamous squamous epithelium that epithelium that lines the interior lines the interior of the circulatory of the circulatory vessels and vessels and heartheartMesothelium

Simple squamous epithelium that lines the peritoneal, pleural and pericardial cavities and covers the viscera

Epithelial cells form themEpithelial cells form them Production & secretion of needed Production & secretion of needed

substancessubstances Are aqueous (water-based) productsAre aqueous (water-based) products The protein product is made in The protein product is made in

rough ER, packed into secretory rough ER, packed into secretory granules by Golgi apparatus, granules by Golgi apparatus, released from the cell by exocytosisreleased from the cell by exocytosis

By where they release their productBy where they release their product•Exocrine: external secretion onto Exocrine: external secretion onto body surfaces (skin) or into body body surfaces (skin) or into body cavitiescavities

•Endocrine: secrete messenger Endocrine: secrete messenger molecules (hormones) which are molecules (hormones) which are carried by blood to target organs; carried by blood to target organs; “ductless” glands“ductless” glands

By whether they are unicellular or By whether they are unicellular or multicellularmulticellular

Exocrine glandsExocrine glandsunicellular or multicellularunicellular or multicellular

Unicellular:Unicellular: goblet cell goblet cell scattered within scattered within

epithelial lining of epithelial lining of intestines andintestines and

respiratory tubesrespiratory tubes

Product:Product: mucinmucin

mucus is mucin & watermucus is mucin & water

Multicellular exocrine Multicellular exocrine glandsglands

Epithelium-walledEpithelium-walled

ductduct and a and a

secretory unitsecretory unit

Examples of exocrine gland Examples of exocrine gland productsproducts

Many types of mucus secreting glandsMany types of mucus secreting glands Sweat glands of skinSweat glands of skin Oil glands of skinOil glands of skin Salivary glands of mouthSalivary glands of mouth Liver (bile)Liver (bile) Pancreas (digestive enzymes)Pancreas (digestive enzymes) Mammary glands (milk)Mammary glands (milk)

Ductless glandsDuctless glands

Release hormones into Release hormones into extracellular spaceextracellular space Hormones are messenger Hormones are messenger moleculesmolecules

Hormones enter blood and Hormones enter blood and travel to specific target organstravel to specific target organs

Epithelial surface featuresEpithelial surface features

Lateral surfaceLateral surface Adhesion proteinsAdhesion proteins Tongue and groove wavy contoursTongue and groove wavy contours Cell junctions: see next slideCell junctions: see next slide

Basal surfaceBasal surface Basal lamina: noncellular sheet of protein Basal lamina: noncellular sheet of protein

together with reticular fibers form basement together with reticular fibers form basement membranemembrane

Cell JunctionsCell Junctions► Tight junctionsTight junctions

So close that are So close that are sometimes sometimes impermeableimpermeable

► Adherens junctionsAdherens junctions Transmembrane linker Transmembrane linker

proteinsproteins

► DesmosomesDesmosomes Anchoring junctionsAnchoring junctions Filaments anchor to the Filaments anchor to the

opposite sideopposite side

► Gap junctionsGap junctions Allow small molecules Allow small molecules

to move between cellsto move between cells

Microvilli – maximize surface areaMicrovilli – maximize surface areaFingerlike extensions of the Fingerlike extensions of the plasma membrane of apical plasma membrane of apical epithelial cellsepithelial cells

On moist and mucus secreting On moist and mucus secreting epitheliumepithelium

Longest on epithelia that absorb Longest on epithelia that absorb nutrients (small intestine) or nutrients (small intestine) or transportions (kidneys)transportions (kidneys)

CiliaCilia Whiplike motile Whiplike motile

extentions of the extentions of the apical surface apical surface membranesmembranes

FlagellumFlagellum Long isolated Long isolated

ciliumcilium Only found as Only found as

sperm in humansperm in human

EpitheliumEpithelium• Connective tissueConnective tissue

Connective tissue proper Connective tissue proper (examples: fat tissue, fibrous (examples: fat tissue, fibrous tissue of ligaments)tissue of ligaments)

CartilageCartilage BoneBone BloodBlood

• Muscle tissueMuscle tissue• Nervous tissueNervous tissue

Classes of Connective Tissue: note the cell types and great variety of subclasses

• Originate from embryonic tissue called Originate from embryonic tissue called mesenchymemesenchyme

• Most diverse and abundant type of tissueMost diverse and abundant type of tissue• Many subclasses (see previous slide)Many subclasses (see previous slide)• Function: to protect, support and bind Function: to protect, support and bind

together other tissuestogether other tissues– Bones, ligaments, tendonsBones, ligaments, tendons– Areolar cushions; adipose insulates and Areolar cushions; adipose insulates and

is food sourceis food source– Blood cells replenished; body tissues Blood cells replenished; body tissues

repairedrepaired• Cells separated from one another by large Cells separated from one another by large

amount of nonliving extracellular matrixamount of nonliving extracellular matrix

Nonliving material between cellsNonliving material between cells Produced by the cells and then Produced by the cells and then

extrudedextruded Responsible for the strengthResponsible for the strength Two componentsTwo components

1.1.Ground substanceGround substanceOf fluid, adhesion proteins, Of fluid, adhesion proteins,

proteoglycansproteoglycansLiquid, semisolid, gel-like or very Liquid, semisolid, gel-like or very

hard hard 2.2.Fibers: collagen, elastic or reticularFibers: collagen, elastic or reticular

Support and binding of other tissuesSupport and binding of other tissues

Holding body fluidsHolding body fluids

Defending the body against infectionDefending the body against infection macrophages, plasma cells, mast macrophages, plasma cells, mast cells, WBCscells, WBCs

Storing nutrients as fatStoring nutrients as fat

Classes of Connective Tissue

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Classes of Connective Tissue

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Classes of Connective Tissue

Classes of Connective Tissue

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Classes of Connective Tissue

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Membranes that combine Membranes that combine epithelial sheets plus epithelial sheets plus underlying connective underlying connective tissue proper (see next tissue proper (see next

slide)slide) Cutaneous membranesCutaneous membranes Skin: epidermis and dermisSkin: epidermis and dermis

Mucous membranes, or mucosaMucous membranes, or mucosa Lines every hollow internal organ that opens to the Lines every hollow internal organ that opens to the

outside of the bodyoutside of the body Serous membranes, or serosaSerous membranes, or serosa

Slippery membranes lining the pleural, pericardial and Slippery membranes lining the pleural, pericardial and peritoneal cavitiesperitoneal cavities

The fluid formed on the surfaces is called a transudateThe fluid formed on the surfaces is called a transudate Synovial membranesSynovial membranes

Line jointsLine joints

(a)Cutaneous membrane

(b)Mucous membrane

(c)Serous membrane

Four basic types of tissueFour basic types of tissue

EpitheliumEpithelium•Connective tissueConnective tissue•Muscle tissueMuscle tissue

SkeletalSkeletalCardiacCardiacSmoothSmooth

•Nervous tissueNervous tissue

EpitheliumEpithelium Connective tissueConnective tissue Muscle tissueMuscle tissue Nervous tissueNervous tissue

NeuronsNeuronsSupporting cellsSupporting cells

Immune: takes longer and is highly specificImmune: takes longer and is highly specific InflammationInflammation

Nonspecific, local, rapidNonspecific, local, rapid Inflammatory chemicalsInflammatory chemicals Signs: heat, swelling, redness, painSigns: heat, swelling, redness, pain

Repair – two waysRepair – two ways RegenerationRegeneration Fibrosis and scarringFibrosis and scarring

Severe injuriesSevere injuries Cardiac and nervous tissueCardiac and nervous tissue

Adenoma – neoplasm of glandular Adenoma – neoplasm of glandular epithelium, benign or malignantepithelium, benign or malignant

Carcinoma – cancer arising in an Carcinoma – cancer arising in an epithelium (90% of all human cancers)epithelium (90% of all human cancers)

Sarcoma – cancer arising in mesenchyme-Sarcoma – cancer arising in mesenchyme-derived tissue (connective tissues and derived tissue (connective tissues and muscle)muscle)

STEM CELLS….STEM CELLS….

STEM CELLS

______ Inner cell mass becomes the baby