4. tissues: living communities

Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc.

Tissues: Living CommunitiesTissues: Living Communities


Learning ObjectivesLearning Objectives Describe the functions of epithelial tissues.Describe the functions of epithelial tissues. Differentiate between the three major types of cellular junctions Differentiate between the three major types of cellular junctions

found between epithelial cells.found between epithelial cells. Describe the structure of the basement membrane.Describe the structure of the basement membrane. List and describe the characteristics used to classify different List and describe the characteristics used to classify different

epithelial tissues. epithelial tissues. List and describe the characteristics used to classify different List and describe the characteristics used to classify different

glands.glands. List and describe the components that make up connective tissues.List and describe the components that make up connective tissues. Differentiate between areolar, adipose, and reticular connective Differentiate between areolar, adipose, and reticular connective

tissues.tissues. Differentiate between dense regular, dense irregular, and elastic Differentiate between dense regular, dense irregular, and elastic

connective tissues.connective tissues. Differentiate between hyaline cartilage, elastic cartilage, and Differentiate between hyaline cartilage, elastic cartilage, and

fibrocartilage.fibrocartilage. List and describe the components of bone.List and describe the components of bone.


Types of TissuesTypes of Tissues

Tissues are classified into the following Tissues are classified into the following four primary types:four primary types:1. Epithelial tissue1. Epithelial tissue

2. Connective tissue2. Connective tissue

3. Muscle tissue3. Muscle tissue

4. Nervous tissue4. Nervous tissue


Epithelial TissuesEpithelial Tissues

Sheets of cells that cover and line other Sheets of cells that cover and line other tissuestissues

Protect underlying tissues and may act to Protect underlying tissues and may act to filter biochemical substancesfilter biochemical substances

May absorb, secrete, or excrete May absorb, secrete, or excrete biochemical substancesbiochemical substances

May play a role in the reception of sensory May play a role in the reception of sensory inputinput


Characteristics of EpitheliaCharacteristics of Epithelia

Each epithelial cell has an apical surface Each epithelial cell has an apical surface and a basal surfaceand a basal surface Apical surface faces the lumen or outside of Apical surface faces the lumen or outside of

the organ the organ Basal surface faces the basal lamina and blood Basal surface faces the basal lamina and blood

vesselsvessels Lateral surfaces are connected to Lateral surfaces are connected to

neighboring cells by junctional complexes.neighboring cells by junctional complexes. Epithelial cells are avascular. Epithelial cells are avascular. Most epithelial cells are innervated.Most epithelial cells are innervated.


Cellular AttachmentsCellular Attachments

Three major types of cellular junctions Three major types of cellular junctions

1. Tight junctions1. Tight junctions

2. Desmosomes2. Desmosomes

3. Gap junctions3. Gap junctions


Tight JunctionsTight Junctions

Formed by the fusion Formed by the fusion of the outermost of the outermost layers of the plasma layers of the plasma membranes of membranes of adjoining cells adjoining cells

Found in tissues in Found in tissues in which there can be no which there can be no leaks (urinary bladder, leaks (urinary bladder, digestive tract) digestive tract)


DesmosomesDesmosomes

Mechanical coupling Mechanical coupling formed by filaments that formed by filaments that interlock with one anotherinterlock with one another

Tonofilaments extend from Tonofilaments extend from the plaque into the the plaque into the cytoplasm.cytoplasm.

Found in tissues that Found in tissues that undergo repeated undergo repeated episodes of tension and episodes of tension and stretching (skin, heart, stretching (skin, heart, uterus) uterus)

Hemidesmosomes link Hemidesmosomes link epithelial cells to the epithelial cells to the basement membrane.basement membrane.


Gap JunctionsGap Junctions Tubular channel proteins Tubular channel proteins

(connexons) that extend (connexons) that extend from the cytoplasm of from the cytoplasm of one cell to the cytoplasm one cell to the cytoplasm of another of another

Allow exchange and Allow exchange and passage of ions and passage of ions and nutrients nutrients

Found in intestinal Found in intestinal epithelial cells, the heart, epithelial cells, the heart, and smooth muscle and smooth muscle tissuetissue


Basement MembraneBasement Membrane

Meshwork of fibers that cements the Meshwork of fibers that cements the epithelial cell to the underlying connective epithelial cell to the underlying connective tissue tissue

Also called Also called basal laminabasal lamina Varies in thickness Varies in thickness Helps prevent the cell from being torn off Helps prevent the cell from being torn off

by intraluminal pressuresby intraluminal pressures Acts as a partial barrier between the Acts as a partial barrier between the

epithelial cell and the underlying epithelial cell and the underlying connective tissueconnective tissue


Surface SpecializationSurface Specialization Surfaces of epithelial Surfaces of epithelial

cellsvary depending on cellsvary depending on where they are located where they are located and what role they play in and what role they play in the function of the tissuethe function of the tissue SmoothSmooth Microvilli (brush Microvilli (brush

border)border) CiliaCilia Keratin.Keratin.


Classification of Epithelial Tissue Classification of Epithelial Tissue

Number of layers of Number of layers of cells: Simple or cells: Simple or stratifiedstratified

Shape of the cells: Shape of the cells: Squamous, cuboidal, Squamous, cuboidal, and columnarand columnar

Presence of surface Presence of surface specializations: Cilia, specializations: Cilia, keratin, etc.keratin, etc.


Simple Squamous EpitheliumSimple Squamous Epithelium

Fragile and thin Fragile and thin Found lining surfaces Found lining surfaces

involved in the passage involved in the passage

of either gas or liquid of either gas or liquid Flat and smoothFlat and smooth


Simple Cuboidal Epithelium Simple Cuboidal Epithelium

Single layer of cube-Single layer of cube-shaped cells shaped cells

Round, dark-stainingRound, dark-stainingnuclei aligned nuclei aligned

in a single row in a single row Occurs in areas of the Occurs in areas of the

body where secretionbody where secretion and absorption and absorption

take placetake place


Simple Columnar Epithelium Simple Columnar Epithelium

Elongated and closely Elongated and closely packed togetherpacked together

Nuclei aligned in a Nuclei aligned in a row at the base of the row at the base of the cell near the cell near the basement membranebasement membrane

Found in many Found in many excretory ducts as excretory ducts as well as in the digestive well as in the digestive tracttract


Stratified Squamous EpitheliumStratified Squamous Epithelium

Multilayered Multilayered Occur in areas of the Occur in areas of the

body subject to mechanical body subject to mechanical

and chemical stressesand chemical stresses Protect underlying Protect underlying

tissuestissues


Stratified Cuboidal EpitheliumStratified Cuboidal Epithelium

Usually two layers of Usually two layers of cuboidal cellscuboidal cells

Found primarily along large Found primarily along large excretory ductsexcretory ducts

Protects underlying tissuesProtects underlying tissues


Stratified Columnar EpitheliumStratified Columnar Epithelium

Found only in select parts Found only in select parts of the respiratory, digestive,of the respiratory, digestive,reproductive systems and reproductive systems and along some excretory ductsalong some excretory ducts

Function in secretion Function in secretion

and protectionand protection


Pseudostratified Columnar Pseudostratified Columnar EpitheliumEpithelium

Cell nuclei are found at different Cell nuclei are found at different

levels across the length of the levels across the length of the tissuetissue

Some cells do not reach the Some cells do not reach the

luminal surface luminal surface Found in respiratory tract and Found in respiratory tract and

in portions of the male in portions of the male

reproductive tractreproductive tract


Transitional EpitheliumTransitional Epithelium

Stratified epithelium with a basal Stratified epithelium with a basal layer of cuboidal or columnar layer of cuboidal or columnar cells and a superficial layer of cells and a superficial layer of cuboidal or squamous cellscuboidal or squamous cells

Found in areas of the body Found in areas of the body required to expand and contract required to expand and contract as part of their normal functionas part of their normal function


Glandular EpitheliumGlandular Epithelium Groups of cells that Groups of cells that

manufacture and discharge a manufacture and discharge a secretionsecretion

Classification of glandsClassification of glands1.1. Presence or absence of ducts Presence or absence of ducts

2.2. Number of cells that compose Number of cells that compose them them

3.3. Shape of the secreting ductsShape of the secreting ducts

4.4. Complexity of the glandular Complexity of the glandular structurestructure

5.5. Type of secretion they produceType of secretion they produce

6.6. Manner in which the secretion is Manner in which the secretion is stored and dischargedstored and discharged


Endocrine GlandsEndocrine Glands

Glands that do not have ducts or tubules Glands that do not have ducts or tubules and whose secretions are distributed and whose secretions are distributed throughout the bodythroughout the body

Produce and secrete Produce and secrete hormones hormones into the into the bloodstream or the lymphatic systembloodstream or the lymphatic system

Part of a complex, biochemical network Part of a complex, biochemical network known as the endocrine systemknown as the endocrine system


Exocrine GlandsExocrine Glands

Discharge secretions via ducts directly into Discharge secretions via ducts directly into local areas (except for goblet cell)local areas (except for goblet cell)

Unicellular or multicellularUnicellular or multicellular


Goblet CellGoblet Cell

Unicellular exocrine Unicellular exocrine gland gland

Ductless and composed Ductless and composed of modified columnar of modified columnar epithelial cell epithelial cell

Found among columnar Found among columnar cells of the respiratory cells of the respiratory and digestive tracts and and digestive tracts and the conjunctiva of the the conjunctiva of the eye eye

Secretes mucinSecretes mucin


Multicellular Exocrine GlandsMulticellular Exocrine Glands

Composed of a secretory unit and a duct Composed of a secretory unit and a duct Secretory unit is usually surrounded by Secretory unit is usually surrounded by

connective tissue rich in blood vessels and connective tissue rich in blood vessels and nerve fibers nerve fibers

May be surrounded by myoepithelial cells May be surrounded by myoepithelial cells that assist with the discharge of secretions that assist with the discharge of secretions into the glandular ductinto the glandular duct


Classification of Exocrine GlandsClassification of Exocrine Glands

Ducts:Ducts: Simple: main duct is unbranched Simple: main duct is unbranched Compound: main duct is branchedCompound: main duct is branched

Shape of secretory portions Shape of secretory portions Tubular: secretory cells form a long channel of Tubular: secretory cells form a long channel of

even widtheven width Alveolar or acinar: secretory unit forms a Alveolar or acinar: secretory unit forms a

rounded sacrounded sac Tubuloalveolar, or tubuloacinar: secretory units Tubuloalveolar, or tubuloacinar: secretory units

possess both tubular and alveolar qualitiespossess both tubular and alveolar qualities



MerocrineMerocrine glands glands package their package their secretions and release secretions and release them via exocytosis as them via exocytosis as they are manufactured. they are manufactured.

ApocrineApocrine glands store glands store their secretions and their secretions and then release the top then release the top part of the cell into the part of the cell into the duct systemduct system

HolocrineHolocrine glands store glands store their secretions and their secretions and then release the entire then release the entire contents of the cellcontents of the cell



Type of secretion producedType of secretion produced Serous secretions Serous secretions

Watery Watery Contain a high concentration of enzymesContain a high concentration of enzymes

Mucous secretionsMucous secretions Thick, viscousThick, viscous Composed of glycoproteins. Composed of glycoproteins.

Mixed exocrine glands contain both Mixed exocrine glands contain both mucousmucous and serous components.and serous components.


Connective TissueConnective Tissue

FunctionsFunctions Forms metabolic and structural connections Forms metabolic and structural connections

between other tissuesbetween other tissues Forms a protective sheath around organs and Forms a protective sheath around organs and

helps insulate the bodyhelps insulate the body Acts as a reserve for energyActs as a reserve for energy Provides the frame that supports the bodyProvides the frame that supports the body Composes the medium that transports Composes the medium that transports

substances from one region of the body to substances from one region of the body to another another

Plays a role in the healing process and in the Plays a role in the healing process and in the control of invading microorganismscontrol of invading microorganisms


Connective Tissue ComponentsConnective Tissue Components

Extracellular matrixExtracellular matrix Extracellular fibersExtracellular fibers Ground substanceGround substance

Cells Cells



Ground substanceGround substance Medium through which cells exchange nutrients Medium through which cells exchange nutrients

and waste with the bloodstreamand waste with the bloodstream Amorphous, homogeneous material Amorphous, homogeneous material Ranges in texture from a liquid or gel to a Ranges in texture from a liquid or gel to a

calcified solidcalcified solid Acts to protect the more delicate cells it Acts to protect the more delicate cells it

envelopesenvelopes Serves as an effective obstacle for invading Serves as an effective obstacle for invading

microorganismsmicroorganisms



Extracellular fibersExtracellular fibers Collagenous fibersCollagenous fibers

Strong, thick strands of collagenStrong, thick strands of collagen Organized into bundles of long, parallel fibrils Organized into bundles of long, parallel fibrils

composed of bundled microfibrilscomposed of bundled microfibrils Variable density and arrangement of fibersVariable density and arrangement of fibers Found in tendons and ligaments Found in tendons and ligaments



Extracellular fibersExtracellular fibers Reticular fibersReticular fibers

Thin, delicate, branched networks of collagenThin, delicate, branched networks of collagen Provide support for highly cellular organs (endocrine Provide support for highly cellular organs (endocrine

glands, lymph nodes, spleen, bone marrow, and liver) glands, lymph nodes, spleen, bone marrow, and liver) Also found around blood vessels, nerves, muscle fibers, Also found around blood vessels, nerves, muscle fibers,

and capillariesand capillaries


Extracellular fibersExtracellular fibers Elastic fibers Elastic fibers

Branched networks composed primarily of the protein Branched networks composed primarily of the protein elastinelastin

Composed of coiled bundles of microfibrilsComposed of coiled bundles of microfibrils Occur in tissues commonly subjected to stretching Occur in tissues commonly subjected to stretching

(vocal cords, lungs, skin, and walls of blood vessels)(vocal cords, lungs, skin, and walls of blood vessels)




Cell TypesCell Types Fixed Cells: involved in production and Fixed Cells: involved in production and

maintenance of the matrixmaintenance of the matrix Fibroblasts, chondroblasts, osteoblasts, adipocytes, Fibroblasts, chondroblasts, osteoblasts, adipocytes,

reticular cellsreticular cells Transient Cells: involved in the repair and Transient Cells: involved in the repair and

protection of tissuesprotection of tissues Leukocytes, mast cells, macrophagesLeukocytes, mast cells, macrophages


Connective Tissue ProperConnective Tissue Proper

Loose connective tissue Loose connective tissue AreolarAreolar AdiposeAdipose ReticularReticular

Dense connective tissue Dense connective tissue Dense regularDense regular Dense irregularDense irregular ElasticElastic


Areolar Connective TissueAreolar Connective Tissue

Loose connective tissue Loose connective tissue Fibers and cells suspended in a Fibers and cells suspended in a

thick, translucent ground substance thick, translucent ground substance Predominant cell is the fibroblastPredominant cell is the fibroblast

Manufactures the elastic, reticular, Manufactures the elastic, reticular, and collagenous fibersand collagenous fibers

Surrounds every organ; forms the SQ Surrounds every organ; forms the SQ layer that connects skin to muscle; layer that connects skin to muscle; envelopes blood vessels, nerves, envelopes blood vessels, nerves, and lymph nodes; present in all and lymph nodes; present in all mucous membranesmucous membranes


Adipose TissueAdipose Tissue

Loose connective tissueLoose connective tissue Areolar tissue in which Areolar tissue in which

adipocytes predominate adipocytes predominate Highly vascularHighly vascular Acts as an energy Acts as an energy

storehouse and a thermal storehouse and a thermal insulator insulator


Reticular Connective TissueReticular Connective Tissue

Loose connective tissue Loose connective tissue Network of thin reticular Network of thin reticular

fibers. fibers. Contains loosely arranged Contains loosely arranged

fibers and many fibroblasts fibers and many fibroblasts suspended in a supportive suspended in a supportive ground substanceground substance

Forms the stroma Forms the stroma (framework of several (framework of several organs)organs)


Dense Regular Connective TissueDense Regular Connective Tissue

Composed of tightly Composed of tightly packed, parallel packed, parallel collagen fibers collagen fibers

Relatively avascular Relatively avascular Makes up the tendons Makes up the tendons

and ligaments and ligaments Can be found in fascial Can be found in fascial

sheets that cover musclessheets that cover muscles


Dense Irregular Connective TissueDense Irregular Connective Tissue

Composed primarily of collagen Composed primarily of collagen fibers arranged in thick bundles fibers arranged in thick bundles

Fibers are interwoven to form a Fibers are interwoven to form a single sheet single sheet

Found in the dermis of the skin Found in the dermis of the skin and in the fibrous coverings of and in the fibrous coverings of many organsmany organs

Forms the tough capsule of jointsForms the tough capsule of joints


Elastic Connective TissueElastic Connective Tissue

Primarily composed of elastic fibersPrimarily composed of elastic fibers Fibers may be arranged parallel or in Fibers may be arranged parallel or in

interwoven patterns with fibroblasts and interwoven patterns with fibroblasts and collagenous fibers interspersedcollagenous fibers interspersed

Found in spaces between vertebrae and in Found in spaces between vertebrae and in areas of the body that require stretching areas of the body that require stretching (walls of arteries, stomach, bronchi, (walls of arteries, stomach, bronchi, bladder, etc.)bladder, etc.)


Specialized Connective TissuesSpecialized Connective Tissues

CartilageCartilage Hyaline cartilageHyaline cartilage Elastic cartilageElastic cartilage FibrocartilageFibrocartilage

BoneBone BloodBlood


CartilageCartilage

Found in joints and in the ear, nose, and vocal Found in joints and in the ear, nose, and vocal cords cords

Forms a framework on which bone is formedForms a framework on which bone is formed No innervation; avascularNo innervation; avascular Cells:Cells:

Chondrocytes: live in hollowed-out pockets in the matrix Chondrocytes: live in hollowed-out pockets in the matrix called called lacunaelacunae

Matrix:Matrix: Ground substance: gel of chondroitin sulfate, hyaluronic Ground substance: gel of chondroitin sulfate, hyaluronic

acid, and chondronectin acid, and chondronectin Collagen fibers are most commonly found in the matrix, Collagen fibers are most commonly found in the matrix,

but elastic fibers are also present in varying amounts.but elastic fibers are also present in varying amounts.


Hyaline CartilageHyaline Cartilage Most common type of cartilage Most common type of cartilage

found in the bodyfound in the body Composed of closely packed Composed of closely packed

collagen collagen FoundFound in jointsin joints at the ends of long at the ends of long

bones, growth plates of long bones, bones, growth plates of long bones, tracheal rings, and connections of tracheal rings, and connections of the ribs to the sternum the ribs to the sternum

Composes most of the embryonic Composes most of the embryonic skeleton Enclosed within a skeleton Enclosed within a perichondriumperichondrium


Elastic CartilageElastic Cartilage

Contains elastic fibers in Contains elastic fibers in dense branching bundles dense branching bundles

Flexible: can withstand Flexible: can withstand repeated bending repeated bending

Found in the epiglottis of the Found in the epiglottis of the larynx and in pinnae of ears larynx and in pinnae of ears of animalsof animals


FibrocartilageFibrocartilage Usually found merged with hyaline Usually found merged with hyaline

cartilage and dense connective cartilage and dense connective tissue tissue

Contains thick bundles of collagen Contains thick bundles of collagen fibers with fewer chondrocytes fibers with fewer chondrocytes than hyaline cartilagethan hyaline cartilage

Lacks a perichondrium Found in Lacks a perichondrium Found in spaces between vertebrae of the spaces between vertebrae of the spine, between bones in the pelvic spine, between bones in the pelvic girdle, and in the knee jointgirdle, and in the knee joint


BoneBone

Matrix is a combination of organic Matrix is a combination of organic collagen fibers and inorganic collagen fibers and inorganic calcium saltscalcium salts

Well vascularizedWell vascularized Haversian canal contains both a Haversian canal contains both a

vascular and a nerve supply vascular and a nerve supply Canaliculi: channels within the Canaliculi: channels within the

matrix support passage of blood matrix support passage of blood vessels into deeper portions vessels into deeper portions of tissue of tissue


BoneBone

Osteoblasts: manufacture the fibers Osteoblasts: manufacture the fibers that are part of the matrixthat are part of the matrix Lacunae and canaliculi are Lacunae and canaliculi are

created as the osteoblasts created as the osteoblasts manufacture the bony matrix. manufacture the bony matrix.

Osteocytes reside in lacunae. Osteocytes reside in lacunae. Cellular extensions pass Cellular extensions pass

through the canaliculi.through the canaliculi.


BloodBlood

Matrix: Matrix: Ground substance: plasma Ground substance: plasma fibrous component: protein fibrous component: protein

CellsCells Erythrocytes Erythrocytes Leukocytes Leukocytes ThrombocytesThrombocytes


Mucous MembranesMucous Membranes

Mucous membranes (mucosae)Mucous membranes (mucosae) Line organs with connections to the outside environment Line organs with connections to the outside environment

(mouth, intestines, nasal passages, etc.)(mouth, intestines, nasal passages, etc.) Usually composed of either stratified squamous or simple Usually composed of either stratified squamous or simple

columnar epithelium covering a layer of loose connective columnar epithelium covering a layer of loose connective tissue tissue

Submucosa : connective tissue layer that connects the Submucosa : connective tissue layer that connects the mucosa to underlying structuresmucosa to underlying structures


Mucous MembranesMucous Membranes

Mucous membranes (mucosae)Mucous membranes (mucosae) May contain goblet cells or multicellular glands May contain goblet cells or multicellular glands

Can produce large quantities of mucus Can produce large quantities of mucus Mucus consists primarily of water, electrolytes, and the protein Mucus consists primarily of water, electrolytes, and the protein

mucinmucin Some mucosae also can absorb (e.g., the epithelial layer in Some mucosae also can absorb (e.g., the epithelial layer in

the intestine)the intestine)


Serous MembranesSerous Membranes

Serous membranesSerous membranes (serosae)(serosae) Line walls and cover organs of body cavities (e.g., thorax and Line walls and cover organs of body cavities (e.g., thorax and

abdominopelvic cavities) abdominopelvic cavities) Consist of a continuous sheet doubled over on itself to form two Consist of a continuous sheet doubled over on itself to form two

layers layers The portion of the membrane that lines the cavity wall is called theThe portion of the membrane that lines the cavity wall is called the

parietal layer.parietal layer. The portion of the membrane that covers the outer surface of The portion of the membrane that covers the outer surface of

organs is called theorgans is called the visceral layer. visceral layer. In abdominopelvic cavity, visceral layers of serosa merge to form In abdominopelvic cavity, visceral layers of serosa merge to form

mesenteries.mesenteries.


Cutaneous MembraneCutaneous Membrane

Also called Also called integumentintegument (or, more simply, (or, more simply, skinskin) ) Composed of an outer keratinized stratified Composed of an outer keratinized stratified

squamous epithelium, or squamous epithelium, or epidermisepidermis Epidermis is attached to an underlying layer of Epidermis is attached to an underlying layer of

dense irregular connective tissue called the dense irregular connective tissue called the dermisdermis. .

Dermis contains collagenous, reticular, and elastic Dermis contains collagenous, reticular, and elastic fibers which enable skin to be both strong and fibers which enable skin to be both strong and elasticelastic


Synovial MembranesSynovial Membranes

Line the cavities of joints Line the cavities of joints Composed of loose connective tissue and Composed of loose connective tissue and

adipose tissue covered by a layer of adipose tissue covered by a layer of collagen fibers and fibroblasts collagen fibers and fibroblasts

Manufacture the synovial fluid that fills the Manufacture the synovial fluid that fills the joint spacesjoint spaces


Muscle TissueMuscle Tissue

Composed of actin and myosin fibersComposed of actin and myosin fibers Three types of muscle tissueThree types of muscle tissue

SkeletalSkeletal SmoothSmooth CardiacCardiac


Skeletal MuscleSkeletal Muscle Large cells that contain hundreds of nuclei Large cells that contain hundreds of nuclei

and mitochondriaand mitochondria Usually controlled through conscious efforts Usually controlled through conscious efforts

(voluntary muscle)(voluntary muscle) Skeletal muscle cells are striated.Skeletal muscle cells are striated. Skeletal muscle cells are bundles of fibers Skeletal muscle cells are bundles of fibers

held together by loose connective tissue. held together by loose connective tissue. The collagen fibers that surround the cells The collagen fibers that surround the cells

merge with merge with the collagen fibers in tendons.the collagen fibers in tendons.


Smooth MuscleSmooth Muscle Composed of small, spindle-shaped cells Composed of small, spindle-shaped cells

that lack striationsthat lack striations Muscle contractions cannot be consciously Muscle contractions cannot be consciously

controlled (nonstriated involuntary muscle)controlled (nonstriated involuntary muscle) Found in the walls of hollow organs, in Found in the walls of hollow organs, in

exocrine glands, and along the exocrine glands, and along the respiratory tract respiratory tract Responsible for Responsible for peristalsisperistalsis in in

gastrointestinal tract, constriction gastrointestinal tract, constriction of blood vessels, and emptying of of blood vessels, and emptying of urinary bladderurinary bladder


Cardiac MuscleCardiac Muscle

Found only in the heart Found only in the heart Contains specialized pacemaker cells Contains specialized pacemaker cells

that supply signal for heart to contract that supply signal for heart to contract at regular intervals at regular intervals

Entirely involuntary and striatedEntirely involuntary and striated Cardiac muscle cells connected to Cardiac muscle cells connected to

one another via one another via intercalated disksintercalated disks


Nervous TissueNervous Tissue

Found in the brain, spinal cord, and Found in the brain, spinal cord, and peripheral nerves peripheral nerves

Composed of two general cell types:Composed of two general cell types: Neurons Neurons Supporting neuroglial cellsSupporting neuroglial cells


Nervous TissueNervous Tissue

NeuronsNeurons Longest cells in the body; Longest cells in the body;

three primary parts:three primary parts: PerikaryonPerikaryon – the cell body; – the cell body;

contains the nucleuscontains the nucleus DendritesDendrites –– short cytoplasmic short cytoplasmic

extensions; receives impulsesextensions; receives impulses AxonsAxons –– long, single extension; long, single extension;

conducts impulses away from conducts impulses away from the cell bodythe cell body

Neuroglial cellsNeuroglial cells Support the neuronsSupport the neurons


Tissue Healing and RepairTissue Healing and Repair

Inflammation: initial response to injuries Inflammation: initial response to injuries Goal: limit further damage and eliminate any Goal: limit further damage and eliminate any

harmful agents harmful agents Repair: involves organization of Repair: involves organization of

granulation tissue and regeneration of lost granulation tissue and regeneration of lost tissue or formation of scar tissuetissue or formation of scar tissue


InflammationInflammation Nonspecific reaction Nonspecific reaction

to injury or diseaseto injury or disease StepsSteps

1.1. VasodilationVasodilation

2.2. SwellingSwelling

3.3. Clot formationClot formation

4.4. PhagocytosisPhagocytosis

5.5. Capillaries return to Capillaries return to normal size, blood normal size, blood flow and fluid leakage flow and fluid leakage into the affected area into the affected area abateabate


Formation of Granulation Tissue and Formation of Granulation Tissue and EpithelializationEpithelialization

Tissue that forms Tissue that forms beneath the beneath the overlying blood clot overlying blood clot or scab or scab

Composed of a layer Composed of a layer of collagen fibers of collagen fibers infiltrated with infiltrated with capillaries (that have capillaries (that have branched off existing branched off existing capillaries in deeper capillaries in deeper layers of damaged layers of damaged tissue)tissue)

Granulation tissue is Granulation tissue is slowly replaced by slowly replaced by fibrous scar tissue.fibrous scar tissue.


Classification of Wound HealingClassification of Wound Healing

First intentionFirst intention:: Edges of wound held in close apposition Edges of wound held in close apposition Skin forms a primary union without formation of Skin forms a primary union without formation of

granulation tissue or significant scarringgranulation tissue or significant scarring Second intentionSecond intention: :

Edges of wound separated from each anotherEdges of wound separated from each another Granulation tissue forms to close gap; scarring resultsGranulation tissue forms to close gap; scarring results

Third intentionThird intention:: Contaminated wound left open until contamination is Contaminated wound left open until contamination is

reduced and inflammation subsides; later closed by reduced and inflammation subsides; later closed by firstfirst intentionintention; also called ; also called delayed primary closuredelayed primary closure

4. tissues: living communities

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