Skeletal system

HistologySTissuesGroups of cells with common embryonic origin and functions4 basic types:EpithelialConnectiveMuscularNervous

EPITHELIAL TISSUESTissues that line and cover body surfaces and may also form glandsDerived from the all three embryonic germ layersTWO MAIN GROUPSMEMBRANE EPITHELIAGLANDULAR EPITHELIACells are closely packed, there is little intercellular space; may be present in one or more layers of cells. Supported by a basement membrane; avascular; 4EPITHELIAL TISSUESArrangement of cells in layersSimple epithelium: 1 layer of cellsStratified Epithelium: more than 1 layer of cellsCell Shapes Squamous Cuboidal Columnar Transitional (change shape)

Classification based on the number of cellsSimplestratified

Simple EpitheliumSquamous= single layer of flat cells.Important for filtration (kidneys) or diffusion (lungs, capillaries) Seen in: Bowmans Capsule, Endothelium, Air Sacs, MesotheliumSimple Squamous Epithelium

Simple Squamous Epithelium

Simple Squamous Epithelium

Single layer of flat cells

Simple Cuboidal EpitheliumSingle Layer of Cuboidal CellsFunction: Secretion, Absorption, TransportationSources: Kidney Tubules, Thyroid Follicle Simple Cuboidal Epithelium

Cube-shaped cells, rounded nuclei

Simple Cuboidal Epithelium

Cube-shaped cells, rounded nuclei

SIMPLE CUBOIDAL EPITHELIUM

SINGLE LAYER OF CUBE LIKE CELLS FUNCTION IS FOR ABSORPTION, SECRETION AND TRANSPORTAtionTissue sources EXCRETORY DUCTS AND TUBULES, SECRETORY DUCTS, THYROID FOLLICLE, KIDNEY TUBULES 15SIMPLE COLUMNAR EPITHELIUM

TALLER THAN WIDE CELLS - GALL BLADDER;;; with Cilia - oviductFUNCTIONS: PROTECTION, LUBRICATION, ABSORPTION, SECRETION COLUMNAR EPITHELIUM MAY POSSESS APICAL SPECIALIZATIONS 16SIMPLE COLUMNAR EPITHELIUM WITH GOBLET CELLS AND MICROVILLI

ILEUM OF SMALL INTESTINE17PSEUDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM WITH GOBLET CELLS

VARIANT OF SIMPLE COLUMNAR EPITHELIUMAPPEAR TO BE Stratified but is actually composed of a single cell; cells different heights, nucleus-TRACHEA FUNCTION SECRETION, TRANSPORTATION, ABSORPTIONOTHER SOURCES PRIMARY BRONCHI, AUDITORY TUBE, NASAL CAVITIES, LACRIMAL SAC 18PSEUDOSTRATIFIED COLUMNAR EPITHELIUM WITH STEREOCILIA

EPIDIDYMIS19Pseudostratified Columnar

Appears stratified; nuclei at various levels

Stratified Squamous EpitheliumApical layer cells are flatDeep layers vary from cuboidal to columnarCells in the basal layer divide and move upward toward apical surfaceFound in areas of surface wear and tearStratified Squamous Epithelium

Stratified Squamous Epithelium

NON KERATINIZING USUALLY WET, CELLS ON THE UPPERMOST LAYER RETAIN THEIR NUCLEIFUNCTION: PROTECTIONUPPER LAYER FLAT CELLSMIDDLE POLYHEDRAL CELLS; BASE COLUMNAR; VAGINAL, TONGUE, MOUTH, 24

STRAT EPITH EPIDERMIS OF SKIN CORNEOCYTES ( RESISTS FRICTION AND IS IMPERMEABLE TO WATER) 25TRANSITIONAL EPITHELIUM

TRANSITIONAL EPITHELIUM UMBRELLA SHAPED UPPER LAYER, PYRIFORM CELLS MIDDLE LAYER; COLUMNAR/POLYHEDRAL CELLS AT THE BASEFUNCTION: UROTHELIUM; TRANSPORTATION AND PROTECTION; DISTENTED OR RELZEXED 26STRATIFIED CUBOIDAL EPITHELIUM

LAYERS OF 2-3 LAYERS OF CUBOIDAL CELLS; RARE TYPEFUNCTION: TRANSPORTATION; MAY PROVIDE TOUGHER LINING; PROTECTION TISSUE SOURCES: SUBMAXILLARY GLAND, SWEAT GLAND27STRATIFIED COLUMNAR EPITHELIUM

MALE URETHRA, CONJUNCTIVA OF EYE TRANSPORTATION AND PROTECTION 28Glandular Epithelium-Endocrine

Glandular Epithelium-Endocrine

Glandular Epithelium-Exocrine

Glandular Epithelium-Exocrine

Connective TissueMost abundant tissue type; typically found between other tissuesFunction: Binding, Protection, SupportDiverse functions that vary by specific tissue typeHas good blood supply; exception: cartilage is avascularConnective TissueComposition:CellsFibersMatrix

Connective Tissue Cells Vary with Tissue TypeFibroblasts: present in several tissuesSecrete fibers & ground substanceMacrophages: formed from monocytesEngulf bacteria and cell debris by phagocytosisPlasma cells: develop from B lymphocytesMake antibodiesConnective Tissue Cells

Mast cells: near blood cellsPart of an inflammatory reaction: produce histamine that dilates blood vesselsAdipocytes: fat cells or adipose cellsStore triglycerides (fat) for energy and provide protectionExtracellular MatrixFluid, gel or solid plus protein fibersGround substance found between cells and fibersFibers Fibers: 3 typesCollagen fibers: very strong and flexibleElastic fibers: smaller stretch and return to original lengthReticular fibers: provide support and strengthFound in basement membranes and organ support

Connective Tissue

Loose Connective TissueAreolarAdiposeReticularAreolar Connective Tissue

Areola Connective Tissue

Adipose Tissue

Adipose Tissue

Reticular Connective Tissue

Reticular Connective Tissue

ClassificationDense Connective tissueDense regularDense irregularElastic

Dense Regular Connective Tissue

Dense Regular Connective Tissue

Dense Irregular Connective Tissue

Dense Irregular Connective Tissue

Elastic Connective Tissue

Elastic Connective Tissue

CartilageDense network of collagen and elastic fibers embedded in chondroitin sulfateStronger than dense fibrous connective tissueCells: chondrocytes Very few; occur singly or in groupsFound in spaces called lacunae within matrixHas no blood vessels or nervesSurrounded by perichondrium which does have blood vessels and nerves

Classification: CartilageTypesHyaline: appears clear because fibers are not easily visibleExample: at ends of long bones, fetal skeletonFibrocartilage: fibers visibleStrongest typeExample: vertebral discs, knee cartilages (menisci)Elastic: chondrocytes in threadlike elastic networkExample: ear cartilageHyaline Cartilage

Hyaline Cartilage

Fibrocartilage

Fibrocartilage

Elastic Cartilage

Elastic Cartilage

Bone: Osseous TissueForms most of the skeleton Supports, protects, and allows movements; site of blood formation and storage of mineralsDense matrix made rigid by calcium and phosphorus saltsLiquid Connective TissueBlood: found within blood vessels Matrix is plasmaCells: red blood cells, white blood cells, plateletsLymph: found within lymph vesselsMatrix is lymph: similar to plasma but with much less proteinSome white blood cellsMuscular TissueFunctions Produce movements, release heatCellsElongated, contractile (called muscle fibers)

Nervous TissueFunction: conduct nerve impulses

Properties:IrritabilityConductivity

Types of cellsNeurons: convert stimuli into nerve impulses and conduct themNeuroglia: do not generate nerve impulses, but serve supportive functions