4 Tissue Level of Organization

© 2011 Pearson Education, Inc.

PowerPoint® Lecture Presentations prepared byAlexander G. CheroskeMesa Community College at Red Mountain

4Tissue Level of Organization


Section 1: Epithelial Tissue

• Learning Outcomes

• 4.1 Describe epithelial tissues, including cell shape, layers, and functions.

• 4.2 Discuss the types and functions of intercellular connections between

epithelial cells.

• 4.3 Describe the structure and function of squamous epithelium.

• 4.4 Describe the structure, function, and locations of cuboidal and transitional epithelia.



• 4.5 Describe the structure, function, and locations of columnar epithelia.

• 4.6 Describe the structure, function, and locations of glandular epithelia.



• Atoms Molecules Cells Tissues

• Chemical level imaged only with special techniques

• Cellular level imaged often with electron microscope

• Body contains trillions of cells

• Only ~200 types of cells

• Tissue level can be imaged with light microscope



• Tissues (cells working together)

• Histology (study of tissues)

• Four basic types

1. Epithelial

2. Connective

3. Muscle

4. Neural


© 2011 Pearson Education, Inc.Figure 4 Section 1

The tissue level of organization, which consists of four tissue types

TheChemicalLevel

TheCellularLevel

TheTissueLevel

MOLECULES ATOMS

CELLSEXTRACELLULAR

MATERIALAND FLUIDS

combineto form

interactto form

thatsecrete

andregulate

combine to form

TISSUESwith special functions

can beclassified as

EPITHELIAL TISSUE CONNECTIVE TISSUE MUSCLE TISSUE NEURAL TISSUE

• Covers exposed surfaces

• Lines internal passageways and chambers

• Produces glandular secretions

• Fills internal spaces

• Provides structural support

• Stores energy

• Contracts to produce active movement

• Conducts electrical impulses

• Carries information


Module 4.1: Epithelial tissue

• Epithelial tissue

• Epithelia

• Cover exposed surfaces and internal cavities/passageways

• Often contain secretory or gland cells

• Scattered among other cell types

• Glands (derived from epithelia but more secretory cells)

• Two types1. Exocrine glands

• Secrete on external areas

2. Endocrine glands

• Secrete hormones into interstitial fluid

© 2011 Pearson Education, Inc.Figure 4.1 1

The components of epithelial tissue

Epithelial Tissue

Epithelia Glands

Exocrine Glands Endocrine Glands

Epithelia cover exposedsurfaces and line internalcavities and passageways;they often containsecretory cells, or glandcells, scattered among theother cell types.

Glands are derivedfrom epithelia, butsecretory cellspredominate; there aretwo types:

Exocrine glands secreteonto external surfaces orinto internal passageways(ducts) that connect to theexterior.

Endocrine glands secretehormones or precursorsinto the interstitial fluid,usually for distribution bythe bloodstream.

Includes


• Functions of epithelial tissue

• Provide physical protection

• Control permeability

• Provide sensation

• Produce specialized secretions



• Basic features of epithelial cells• Apical surface (faces exterior or internal space)

• Microvilli often found on cells of digestive, urinary, and reproductive tracts

• Cilia often found on cells lining respiratory and some parts of reproductive tracts

• Faces lumen (space) when lining hollow organs

• Base (attached to adjacent tissues)

• Basolateral surfaces • Includes base and lateral surfaces (attached to neighboring

cells)

• Have membranous organelles comparable to other cell types



• Three epithelial cell shapes (perpendicular section)

1. Squamous (thin and flat)

2. Cuboidal (small boxes)

3. Columnar (slender rectangles)

• Can be layered

• Single layer (simple epithelium)

• Several layers (stratified epithelium)

• Generally located in areas that need protection



Module 4.1 Review

a. List four essential functions of epithelial tissue.

b. Summarize the classification of an epithelium based on cell shape and number of cell layers.

c. What is the probable function of an epithelial surface whose cells bear many cilia?


Module 4.2: Epithelial cells are extensively interconnected

• Many types of connections to form complete cover or lining

• Have ability to replace damaged or lost cells

• Lack blood vessels (avascular)

• Lowest cell layers must remain attached to underlying tissues to be near blood vessels

Animation: Intercellular Connections


The structures that connect epithelial cells toeach other and to adjacent tissues

Intercellular attachments

Occluding junctions form abarrier that isolates thebasolateral surfaces and deepertissues from the contents of thelumen.

An adhesion belt locks togetherthe terminal webs of neighboringcells, strengthening the apicalregion and preventing distortionand leakage at the occludingjunctions.

Gap junctions permit chemicalcommunication that coordinatesthe activities of adjacent cells.

Desmosomes (DEZ-mō-sōms;desmos, ligament + soma, body)provide firm attachment betweenneighboring cells by interlockingtheir cytoskeletons.

Hemidesmosome

BASE

APICAL SURFACEMicrovilli

Basal Lamina


• Hemidesmosomes

• Made of peripheral and transmembrane proteins

• Attach deepest epithelial cells to basal lamina

• Basal lamina (basement membrane) layers

1. Clear layer (lamina lucida)

• Contains glycoproteins and fine protein filaments

2. Dense layer (lamina densa)

• Contains bundles of coarse protein fibers

• Gives strength and restricts diffusion




Intermediatefilaments of the

cytoskeleton

Hemidesmosome

A hemidesmosome, whichattaches the deepest epithelialcells to the basal lamina

Basal Lamina

The basal lamina, or basement membrane, isa complex structure produced by the basalsurface of the epithelium and the underlyingconnective tissue.

The clear layer, or lamina lucida (LAM-i-nahLOO-si-dah; lamina, thin layer + lucida, clear)contains glycoproteins and a network of fineprotein filaments.

The dense layer, or lamina densa, containingbundles of coarse protein fibers, gives thebasal lamina its strength and acts as a filterthat restricts diffusion between the adjacenttissues and the epithelium.


• Types of intercellular attachments

• Occluding junctions

• Form barrier that prevents lumen contents from getting past cells

• Adjacent plasma membranes tightly bound with proteins

• Adhesion belt

• Attaches terminal webs of adjacent cells

• Reinforces occluding junctions

• Dense protein band surrounding cell




An occluding junction

At an occluding junction,the lipid portions of thetwo plasma membranesare tightly boundtogether by interlockingmembrane proteins.


The structures that connect epithelial cellsto each other and to adjacent tissues

An adhesion belt


• Types of intercellular attachments (continued)

• Gap junctions

• Permit chemical communication to coordinate activities of adjacent cells

• Formed by interlocking junctional proteins (connexons)

• Examples: ciliated epithelial tissues, cardiac muscle tissue

• Desmosomes (desmos, ligament + soma, body)

• Interlock cytoskeletons of adjacent cells

• Very strong

• Formed by:

• Cell adhesion molecules (CAMs)

• Intercellular cement (thin layer of proteoglycans, notably hyaluronan)




An jap junction

Connexons are channelproteins that form a narrow passageway andlet small molecules andions pass from cell tocell.



A desmosome

Cell adhesionmolecules (CAMs) aretransmembrane proteinsthat bind to each otherand to extracellularmaterials.

The membranes ofadjacent cells may alsobe bonded byintercellular cement,a thin layer ofproteoglycans thatcontain polysaccharidederivatives, most notablyhyaluronan.


Module 4.2 Review

a. Identify the various types of epithelial intercellularconnections.

b. How do epithelial tissues, which are avascular, obtain needed nutrients?

c. What is the functional significance of gap junctions?


Module 4.3: Squamous epithelia

• Simple squamous epithelium (squama, plate or scale)• Thin and flat, irregular in shape

• Surface view: like fried eggs side to side

• Sectional view: jigsaw pieces with disc-shaped nucleus

• Found in protected regions• Where absorption or diffusion takes place

• Examples: along kidney passages, inside eye, alveoli of the lung

• Where a slippery surface reduces friction• Lining ventral body cavity (mesothelium)

• Lining heart and blood vessels (endothelium)


Simple squamous epithelia, which include the speciallynamed endothelium and mesothelium

Endothelium lining theinside of the heart andblood vessels

Mesothelium lining thepericardial cavity andthe peritoneal cavity

Connectivetissue

Sectionedepithelial cell

The surfaceof a simplesquamousepithelium

Section ofperitoneum

Nucleus Cytoplasm

Simple squamous epithelium LM x 270



• Stratified squamous epithelium

• Located where mechanical or chemical stresses are severe

• Series of layers

• Example locations: skin, mouth, throat, esophagus, rectum, anus, vagina


Connectivetissue

Basal lamina

Stem cells

Squamoussuperficial cells

Surface of the tongue LM x 400

A stratified squamous epithelium


• Stratified squamous epithelium

• Two types

1. Keratinized (with keratin proteins)

• Tough and water resistant

• Found at surface of skin

2. Nonkeratinized

• Resists abrasion but can dry out

• Found in oral cavity, pharynx, esophagus, anus, vagina



The structure of a keratinized stratifiedsquamous epithelium

Surface of human skin

Keratinized skin cells Keratin fibers


Module 4.3 Review

a. What properties are common to keratinized epithelia?

b. Why do the pharynx, esophagus, anus, and vagina have a similar epithelial organization?

c. Under a light microscope, simple squamous epithelium is seen on the outer surface. Could this be a skin surface sample? Why or why not?


Module 4.4: Cuboidal and transitional epithelia

• Cuboidal epithelium

• Cells resemble hexagonal boxes with nucleus in center

• Types

1. Simple cuboidal epithelium

• Locations

• Lining exocrine glands and ducts

• Portions of kidney

• Secretory chambers of thyroid gland

2. Stratified cuboidal epithelium

• Rare

• Locations

• Ducts of various exocrine glands

© 2011 Pearson Education, Inc.Figure 4.4 1 – 3

Examples of cuboidal epitheliaConnective

tissue

Basal laminaSimple

cuboidal cells

Lumenof duct

Nucleus

A cuboidal epithelium LM x 1400

The simple cuboidal epithelium in a sectionedkidney tubule

Lumenof duct

Stratifiedcuboidal cells

Basallamina

Nuclei

Connectivetissue

The stratified cuboidalepithelium in a sweat gland duct

LM x 1413


• Transitional epithelium

• Unusual stratified epithelium that stretches and recoils

• Transitional = changes

• Locations

• Urinary bladder

• Urethra

• Urine-collecting chambers of kidneys

Module 4.4: Cuboidal and transitional epithelia


The transitional epithelium in an empty and a full urinary bladder

Epithelium in a Relaxed Bladder

Relaxed bladder

Epithelium(relaxed)

Basal lamina

Connective tissue andsmooth muscle layers

LM x 400

In an empty urinary bladder,the superficial cells arecuboidal with a dome-shapedsurface.


Module 4.4 Review

a. Identify the epithelium that lines the urinary bladder and changes in appearance as stretching occurs.

b. Describe the appearance of simple cuboidal epithelial cells in sectional view.

c. Stratified cuboidal epithelia are associated with what epithelial structures?


Module 4.5: Columnar epithelia

• Columnar epithelium

• Cells appear rectangular in sectional view

• Elongated nuclei near basal lamina

• Types

1. Simple columnar epithelium

• Locations

• Stomach

• Intestine

• Uterine tubes

• Kidney ducts


The simpler columnar epithelium in theintestinal lining

Microvilli

Cytoplasm

Nucleus

Basal lamina

Loose connective tissue

LM x 350



• Types (continued)

2. Pseudostratified columnar epithelium• Varying cell shapes and functions

• Nuclei located at different areas of cell, so appears stratified

• Every cell attached to basal lamina

• Cells typically possess cilia

• Locations

• Nasal cavities

• Trachea

• Larger airways of lungs



The pseudostratified columnar epithelium in the trachea

LM x 394

Cilia

Cytoplasm

Nuclei

Basallamina

Looseconnective

tissue



• Types (continued)

3. Stratified columnar epithelium

• Relatively rare

• Either two or multiple layers

• In multiple layers, only superficial cells are columns

• Located in large ducts of salivary glands and pancreas



The stratified columnar epithelium in a salivary gland duct

Lumen Lumen

LM x 175

Looseconnective

tissue

Basalcells

Superficialcolumnar cells

Cytoplasm

Nuclei

Basallamina


Module 4.5 Review

a. Describe the appearance of simple columnarepithelial cells in a sectional view.

b. Explain why a pseudostratified columnar epithelium is not truly stratified.

c. The columnar epithelium lining the intestine typically has ___________ on its apical surface.


Module 4.6: Glandular epithelia

• Glands

• Collections of epithelial cells that produce secretions

• Can be scattered cells or complex organs

• Two types of glandular organs

1. Endocrine glands (secretions into interstitial fluid)

• More information in later chapter

2. Exocrine glands (secretions into ducts that open onto epithelial surface)


• Exocrine glands

• Three types of secretion

1. Merocrine secretion (meros, part)

• Product released from secretory vesicles by exocytosis

• Most common type of secretion

• Mucin

• Merocrine secretion that mixes with water to form mucus

• Used as lubricant, protective barrier, and trap for foreign particles and microorganisms



• Exocrine glands

• Three types of secretion (continued)

2. Apocrine secretion (apo-, off)

• Loss of apical surface and cytoplasm with secretion

• Example: mammary glands

• Merocrine and apocrine secretions in milk

3. Holocrine secretion (holos, entire)

• Entire cell bursts, releasing secretion and killing cell

• Replaced by stem cell division

Animation: Mechanisms of Glandular Secretion



The three types of secretion byglandular epithelial cells

Salivary gland

Mammarygland

Hair

Sebaceous gland

Hair follicle

Mucin is a merocrine secretion thatmixes with water to form mucus.Mucus is an effective lubricant, aprotective barrier, and a sticky trap forforeign particles and microorganisms.

Secretory vesicle(containing mucin)

Golgiapparatus

Nucleus

TEM x 3120

In merocrine secretion (MER-u-krin; meros, part), theproduct is released from secretory vesicles by exocytosis. Thisis the most common mode of secretion.

Breaksdown

Golgi apparatus

Apocrine secretion (AP-ō-krin; apo-, off) involves the loss of cytoplasmas well as the secretory product. The apical portion of the cytoplasmbecomes packed with secretory vesicles and is then shed. Milk productionin the mammary glands involves a combination of merocrine and apocrinesecretions.

SecretionRegrowth

Stem cell

Cells burst, releasingcytoplasmic contents.

Cells producesecretion, increasingin size.

Cell division replaceslost cells.

Start

Holocrine secretion (HOL-ō-krin; holos, entire), by contrast, destroysthe gland cell. During holocrine secretion, the entire cell becomes packedwith secretory products and then bursts, releasing the secretion andkilling the cell. Further secretion depends on the replacement of destroyedgland cells by the division of stem cells.


• Multicellular exocrine gland structure

• Gland classification

• Based on duct structure

• Simple (single duct that does not divide)

• Compound (duct divides one or more times)

• Based on structure of secretory area

• Tubular (glandular cells form tubes)

• Alveolar or acinar (glandular cells form sacs)

• Tubuloalveolar (glandular cells form tubes and sacs)



Simple exocrine glands

Glandcells

Duct

A gland is branched if several secretory areas(tubular or acinar) share a duct. Note that“branched” refers to the glandular areas andnot to the duct.

SIMPLETUBULARExamples:• Intestinal glands

SIMPLE COILEDTUBULARExamples: Examples: Examples: Examples:• Merocrine sweat glands

• Gastric glands• Mucous glands of esophagus, tongue, duodenum

• A stage in the em- bryonic development of simple branched glands

• Sebaceous (oil) glands

Glands whose glandular cells form tubes aretubular; the tubes may be straight or coiled.

Glands whose glandular cells form sac-likepockets are alveolar (al-VĒ-ō-lar; alveolus,sac) or acinar (AS-i-nar; acinus, chamber).

SIMPLE BRANCHEDTUBULAR

SIMPLE ALVEOLAR(ACINAR)

SIMPLE BRANCHEDALVEOLAR


Compound exocrine glands

Glands whose secretorycells form both tubesand sacs are calledtubuloalveolar.

COMPOUNDTUBULAR

COMPOUND ALVEOLAR(ACINAR)

COMPOUNDTUBULOALVEOLAR

Examples: Examples: Examples:• Mucous glands (in mouth)• Bulbo-urethral glands (in male reproductive system)• Seminiferous tubules of testes

• Mammary glands • Salivary glands• Glands of respiratory passages• Pancreas


• Unicellular glands

• Individual, scattered secretory cells (mucous cells)

• Secrete mucin

• Apical cytoplasm filled with large secretory vesicles



A mucous cell in a ciliatedcolumnar epithelium

Mucin

Golgiapparatus

Nucleus

Mucous cell


Module 4.6 Review

a. Name the two primary types of glands.

b. What mode of secretion occurs in the secretory cells of sebaceous glands, which fill with secretions and then rupture, releasing their contents?

c. Which type of gland has no ducts to carry theglandular secretions, and the gland’s secretions are released directly into the interstitial fluid?


Section 2: Connective Tissues


• 4.7 Describe the structure, function, and locations of areolar connective tissue,

adipose tissue, and reticular tissue.

• 4.8 Describe the structure, function, and locations of dense connective tissues

and fluid connective tissues.

• 4.9 Describe the structure, function, and locations of cartilage.



• 4.10 Describe the structure and function of bone.

• 4.11 Describe the arrangements of epithelial and connective tissues in the four

types of membranes.



• Connective tissues

• Vary in appearance and function

• Throughout body but never exposed to outside

• Many have blood vessels and sensory receptors

• All share three basic components

1. Specialized cells

2. Extracellular protein fibers

3. Fluid (ground substance)

• Extracellular fibers and fluid make up matrix that surrounds cells

• Fewer cells and more extracellular material compared to epithelial cells



The three types of connective tissue andexamples of each

Connective Tissue

Connective Tissue Proper Fluid Connective Tissues Supporting Connective Tissues

The various types of connective tissue are situatedthroughout the body but they are never exposed to theoutside environment. Many types of connective tissueare highly vascular (that is, they have many bloodvessels) and contain sensory receptors that detectpain, pressure, temperature, and other stimuli.

Fluid connective tissueshave distinctive populations ofcells suspended in a waterymatrix that contains dissolvedproteins.

Connective tissue properincludes those connective tissueswith many types of cells andextracellular fibers in a syrupyground substance.

Supporting connective tissuesdiffer from connective tissue properin having a less diverse cellpopulation and a matrix containingmuch more densely packed fibers.Supporting connective tissuesprotect soft tissues and support theweight of part or all of the body.

Loose Dense Blood Lymph Cartilage Bone

Fibers create loose,open framework

• areolar tissue • dense regular

• reticular tissue

Fibers denselypacked

• adipose tissue • dense irregular• elastic

Flows within

cardiovascularsystem

Flows withinlymphaticsystem

Solid, rubberymatrix

Solid, crystallinematrix

• hyaline cartilage• elastic cartilage• fibrous cartilage


• Connective tissue types

• Connective tissue proper (many types of cells, fibers with syrupy ground substance)

• Loose (fibers create loose, open framework)

• Dense (fibers densely packed)

• Fluid connective tissues (watery matrix)

• Blood (in cardiovascular system)

• Lymph (in lymphatic system)



• Connective tissue types (continued)

• Supporting connective tissues (less diverse cells, matrix with densely packed fibers)

• Cartilage (solid, rubbery matrix)

• Bone (solid, crystalline matrix)



Module 4.7: Loose connective tissues

• Connective tissue proper components

• Extracellular protein fibers

• Viscous ground substance

• Two classes of cells

1. Fixed

• Stationary

• Function in maintenance, repair, and storage

2. Wandering

• Move throughout tissue

• Function in defense and repair


• Connective tissue proper components (continued)

• Extracellular protein fibers (continued)

• Reticular fibers (strong and form branching network)

• Collagen fibers (thick, very strong)

• Elastic fibers (slender, very stretchy)




• Ground substance

• Clear

• Colorless

• Viscous (syrupy) due to presence of proteoglycans and glycoproteins




• Fixed cells

• Melanocytes (synthesize melanin pigment)

• Fixed macrophage (engulfs cell debris and pathogens)

• Mast cells (stimulate inflammation and mobilize defenses)

• Fibroblasts (synthesize extracellular fibers)

• Adipocytes (store lipid reserves)




• Wandering cells

• Plasma cells (immune cell producing antibodies)

• Free macrophages (engulf debris and pathogens)

• Mesenchymal cells (stem cells that aid tissue repair)

• Neutrophils and eosinophils (phagocytic blood cells)

• Lymphocytes (immune system cells)



The components of areola tissue

Fibers

Reticularfibers arestrong and forma branchingnetwork.

Collagen fibers arethick, straight or wavy,and often formbundles. They are verystrong and resiststretching.

Elastic fibers areslender, unbranching,and very stretchy.They recoil to theiroriginal length afterstretching ordistortion.

Fixed Cells

A melanocyte is afixed pigment cell thatsynthesizes melanin, abrownish-yellowpigment.

A fixed macrophageis a stationary phagocytic cell thatengulfs cell debris andpathogens.

Mast cells are fixedcells that stimulate local inflammation andmobilize tissuedefenses.

Fibroblasts are fixedcells that synthesize the extracellular fibers of the connective tissue.

Adipocytes (fat cells)are fixed cells that store lipid reserves in large intracellular vesicles.

Red blood cellin vessel

Ground substance fills the spaces betweencells and surrounds connective tissue fibers.In all forms of connective tissue proper,ground substance is clear, colorless, andviscous (syrupy) due to the presence ofproteoglycans and glycoproteins.

Lymphocytes aremobile cells of theimmune system.

Neutrophils andeosinophils are small,mobile, phagocyticblood cells that entertissues during infectionor injury.

Mesenchymal cellsare mobile stem cellsthat participate in therepair of damagedtissues.

Free macrophagesare wanderingphagocytic cells thatpatrol the tissue,engulfing debris orpathogens.

A plasma cell is anactive, mobile immunecell that producesantibodies.

Wandering Cells


• Three types of loose connective tissues

1. Areolar tissue

• Most common connective tissue proper

• Packing material of the body

• Has all connective tissue proper cell types

2. Adipose tissue

• Found deep to skin in various areas of body

• Mostly cells (adipocytes)



The structure of adipose tissue deep to the skin

Adipocytes

LM x 340


• Three types of loose connective tissues (continued)

3. Reticular tissue

• Found in liver, kidney, spleen, lymph nodes, and bone marrow

• Provides support and resists distortion

• Many reticular fibers forming network (stroma)



The structure of reticular tissue in the liver

Reticularfibers

LM x 375


Module 4.7 Review

a. Identify the types of cells found in connective tissue proper.

b. Which type of connective tissue contains primarily lipids?

c. Describe the role of fibroblasts in connective tissue.


Module 4.8: Dense and fluid connective tissues

• Dense connective tissues

• Most volume occupied by extracellular fibers

• Three types

1. Dense regular connective tissue

• Found in tendons, ligaments, organ cords

• Has parallel collagen fibers

2. Dense irregular connective tissue

• Found covering visceral organs; in superficial layers of bones, cartilages, and peripheral nerves; in dermis

• No consistent pattern of fiber arrangement


• Dense connective tissues (continued)

• Three types (continued)

3. Elastic tissue

• More elastic fibers than collagen

• Is springy and resilient

• Found between vertebrae, in walls of large blood vessels, erectile tissues of penis



The three types of dense connective tissues

Collagenfiber

Fibroblastnuclei

Dense regular connective tissue in a tendon from the triceps muscle

Dense irregular connective tissue from the dermis

Collagenfiber

bundles

LM x 440

LM x 111

Elastic tissue from a ligament between vertebrae

Elasticfibers

Fibroblastnuclei

LM x 887


• Fluid connective tissues

• Fluid matrix with many suspended proteins

• Normally without fibers

• Types

1. Blood

• Components

• Watery matrix (plasma)

• Cells and cell fragments (formed elements)

2. Lymph

• Components

• Watery matrix (lymph)

• Cells (mainly lymphocytes)



• Formed elements of blood

• Red blood cells (transport oxygen)

• White blood cells (bodily defense)

• Monocytes (large phagocytes)

• Lymphocytes (uncommon in blood)

• Eosinophils/neutrophils (small phagocytes)

• Basophils (promote inflammation)

• Platelets (involved in clotting response)



• Fluid connective tissue locations and functions

• Blood

• Normally moved by heart through blood vessels

• Arteries (away from heart)

• Capillaries (smallest vessels; sites of exchange)

• Veins (toward heart)

• Exchanges water and solutes between plasma and interstitial fluid



The formed elements in blood, a fluid connective tissue with a watery matrix called plasma

Red blood cells areformed elementsresponsible for thetransport of oxygen(and, to a lesserdegree, of carbondioxide) in the blood.

Red Blood Cells White Blood Cells

Red blood cellsaccount for roughlyhalf the volume ofwhole blood andgive blood its color.

White blood cells are formed elementsthat help defend the body from infectionand disease.

Monocytesare phagocytessimilar to thefree macro-phages inother tissues.

Lymphocytes areuncommon in theblood but they are thedominant cell type in lymph, the secondtype of fluidconnective tissue.

Eosinophils andneutrophils arephagocytes. Basophilspromote inflammationmuch like mast cells inother connective tissues.

Eosinophil

Neutrophil

Basophil

Platelets

Platelets areformed elementsconsisting ofmembrane-enclosedpackets ofcytoplasm.

These cellfragments areinvolved in theclotting responsethat seals leaks indamaged or brokenblood vessels.


• Fluid connective tissue locations and functions (continued)

• Lymph

• Located in lymphatic vessels

• Collected from interstitial fluid

• Returned to blood at large veins near heart

• Functions to maintain solute levels, blood volume, and alert immune system of infection



Capillaries are the smallest and mostdelicate blood vessels. All exchangebetween the blood and interstitial fluidoccurs at capillaries.

At capillary networks, bloodpressure forces water and smallsolutes out of the bloodstreamand into the surroundinginterstitial fluid.

Lymph forms as interstitial fluidenters lymphatic vessels.

Lymphatic vessels form anetwork that returns lymph tolarge veins near the heart.

Arteries carry bloodaway from the heart andinto the tissues of thebody.

Veins carry blood fromcapillary beds to theheart.

Heart

Water andsolutes frombloodstream

The continuous circulation of extracellular fluid, including the fluid connective tissue called lymph

Start


Module 4.8 Review

a. Which two types of connective tissue have a liquid matrix?

b. Lack of vitamin C in the diet interferes with the ability of fibroblasts to produce collagen. How might this affect connective tissue function?

c. Summarize the role of extracellular fluid in maintaining homeostasis.


Module 4.9: Cartilage

• Cartilage

• Matrix is firm gel containing polysaccharide derivatives (chondroitin sulfates [chondros, cartilage])

• Forms complexes with proteins producing proteoglycans

• Cells (chondrocytes)

• Only cells in cartilage matrix

• Occupy small chambers (lacunae [lacus, lake])


• Cartilage properties

• Depend on matrix proteoglycans as well as type and abundance of extracellular fibers

• Set apart from surrounding tissues by perichondrium (peri-, around)

• Two layers of perichondrium

1. Outer layer of dense regular connective tissue

• Mechanical support, protection, attachment

2. Inner cellular layer

• Where cartilage growth and maintenance occur



The perichondrium, which separatescartilage from surrounding tissues Perichondrium

Hyaline cartilage LM x 250


• Three types

1. Hyaline cartilage

• Found between ribs and sternum, covering bones in mobile joints, certain areas of respiratory system

• Stiff but flexible support and reduces friction

2. Elastic cartilage

• Supports external ear and other smaller internal structures

• Increased flexibility




3. Fibrous cartilage

• Found within knee joint, between pubic bones of pelvis, in intervertebral discs

• Resists compression, prevents bone-to-bone contact, and limits relative movement



The three types of cartilage

Hyaline cartilage from shoulder joint

Chondrocytesin lacunae

Matrix

LM x 500

Chondrocytein lacuna

Elastic fibersin matrix

Elastic cartilage from external ear

Collagenfibers inmatrix

Chondrocytes

Fibrous cartilage from intervertebral disc

LM x 358

LM x 400


• Cartilage growth

• Two types

1. Appositional growth (at cartilage surface)

• Chondroblasts (immature chondrocytes) divide in cellular layer of perichondrium

• Chondroblasts secrete new matrix

• Once surrounded by matrix, chondroblasts mature into chondrocytes



• Cartilage growth

• Two types (continued)

2. Interstitial growth (within cartilage)• Chondrocytes divide within a lacuna

• Daughter cells secrete additional matrix and move apart

• Both types occur during development

• Normally no growth and repair in adults

• With slight damage or with hormonal stimulation, some appositional growth possible



The types of cartilage growth

Appositional Growth

Dividing stem cellFibroblast

Perichondrium

Chondroblasts

In appositionalgrowth, thecartilage enlargesby the addition ofcartilage to theouter surface.

Cells in the cellularlayer of theperichondriumdifferentiate intochrondroblasts (im-mature chrondrocytes).

The chondroblastssecrete new matrixand becomeseparated from eachother.

Divisions of stem cells in theperichondrium continuouslyproduce additionalchondroblasts. Meanwhile,chondroblasts completelysurrounded by matrix graduallymature into chondrocytes.

New matrix

Maturechondrocytes

Older matrix

New matrix

As daughter cells secret additionalmatrix, they move apart, expandingthe cartilage from within.

A chondrocyte undergoesdivision within a lacunasurrounded by cartilagematrix.

Matrix

ChondrocyteLacuna

Interstitial Growth

In interstitialgrowth, thecartilageexpands fromwithin.


Module 4.9 Review

a. Mature cartilage cells are called __________.

b. Which connective tissue fiber is characteristic of the cartilage supporting the ear?

c. If a person has a herniated intervertebral disc, which type of cartilage has been damaged?


Module 4.10: Bone

• Osseous tissue (os, bone) structure

• Bony matrix

• Small volume of ground substance

• 2/3 of matrix is calcium salts (provide strength)

• Mostly calcium phosphate

• Some calcium carbonate

• Many collagen fibers (provide flexibility)


• Comparison of cartilage and bone

• Both support and protect

• Cartilage is avascular; bone is highly vascular

• Cartilage cannot grow/repair; extensive remodeling and repair in bone

Module 4.10: Bone


• Typical long bone structure

• Hollow with two types of bone

1. Spongy bone

• Lines internal cavity

2. Compact bone

• Outer layer of bone

Module 4.10: Bone


The structure of a long bone, which consistsof compact bone and spongy bone

In compact bone the matrix isorganized in concentric layersaround branches of bloodvessels within the bone.

Compact bone also has asuperficial layer of bone thatwas deposited during appositional growth of thebone. Because the matrix is solid and calcified, interstitialgrowth cannot occur in bone.

Compactbone

Spongybone

Unlike cartilage, boneis highly vascular.Large vesselsoutside the bone areconnected to smallervessels that supplyareas of compactbone and the softtissues that fill theinterior cavity.


• Compact bone structure

• Matrix organized in concentric layers

• Organized into functional units (osteons)

• Central canal contains blood vessels in center

• Cells (osteocytes) located between layers

• Canaliculi (little canals) connect osteocytes

• Superficial layer of bone prevents interstitial growth

Module 4.10: Bone


• Compact bone structure (continued)

• Surrounded by periosteum

• Two layers

1. Outer fibrous layer allows attachment of ligaments

2. Inner cellular layer allows appositional growth and repair

Module 4.10: Bone


The structural features of compact bone, including itsfunctional unit, the osteon

Except in joint cavities, where they are covered by alayer of hyaline cartilage, bone surfaces are sheathedby a periosteum (per-ē-OS-tē-um) composed offibrous (outer) and cellular (inner) layers.

Osteon Matrix

Lacunae

Canaliculi

Layers of the Periosteum

The fibrous layer assists in the attachmentof a bone to surrounding tissues and toassociated tendons and ligaments.

The cellular layer functions inappositional bone growth and participatesin repairs after an injury.

Lacunae in the matrix containosteocytes (OS-tē- ō-sīts), or bone cells.The lacunae are typically organizedaround blood vessels that branchthrough the bony matrix.

Layers of matrix separate the lacunae.These layers are oriented along the mainaxis of the bone.

Canaliculi (kan-a- LIK-ū-lē; little canals)are fine passageways that form a branching network for the exchange ofmaterials between blood vessels andosteocytes. This is important becausediffusion cannot occur through thecalcified matrix of bone.

A central canal at the center of anosteon contains the blood vessels thatprovide oxygen and nutrients to the osteocytes.

LM x 320


Module 4.10 Review

a. Mature bone cells in lacunae are called ____________.

b. Distinguish between the two types of supporting connective tissues with respect to their characteristic fibers.

c. Explain why bone does not undergo interstitial growth.


Module 4.11: Membranes and fasciae

• Membranes

• Line or cover body surfaces

• Consist of epithelium supported by connective tissue

• Four types

1. Mucous membranes• Line organs that communicate to exterior

• Must be kept moist to facilitate movement, absorption, or secretion

• Lubricated by mucus or bodily fluids

• Supported by areolar connective tissue (lamina propria)


• Membranes (continued)

• Four types (continued)

2. Serous membranes

• Mesothelium supported by areolar connective tissue

• Delicate and never connected to exterior

• Transudate (liquid layer) coats surface

• Three line subdivisions of ventral body cavity

• Pleura (pleural cavity and lungs)

• Peritoneum (peritoneal cavity and visceral organs)

• Pericardium (pericardial cavity and heart)





3. Cutaneous membrane

• Covers surface of body

• = Skin

• Relatively thick, waterproof, and dry comparatively





4. Synovial membranes• Line mobile joint cavities

• Similar to epithelia but not

• Develops within connective tissue

• No basal lamina

• Gaps between cells (up to 1 mm)

• Exchange fluid (synovial fluid) and solutes with cardiovascular capillaries



• Fasciae

• Connective tissue layers and wrappings

• Support and surround organs

• Three types

1. Superficial fascia• Under skin

• Consists of areolar and adipose tissue

2. Deep fascia• Continuous with capsules, ligaments, and other connective

tissue structures

• Consists of dense irregular connective tissue



• Fasciae (continued)


3. Subserous fascia

• Between serous membranes and deep fascia

• Consists entirely of areolar tissue



Skin

Body wall

Bodycavity

Serous membrane lining body cavity

Rib

Cutaneous membrane of the skin

The structure and function of fasciae

Connective Tissue Framework of Body

The SuperficialFascia

The DeepFascia

The SubserousFascia

• Lies between the skin and underlying organs

• Consists of areolar tissue and adipose tissue

• Forms a strong, fibrous internal framework

• Consists of dense irregular connective tissue

• Is continuous with or bound to capsules, ligaments, and other connective tissue structures

• Lies between serous membranes and deep fascia

• Consists entirely of areolar tissue


Module 4.11 Review

a. Name the four types of membranes found in the body.

b. Which cavities in the body are lined by serous membranes?

c. A sheet of tissue has many layers of collagen fibers that run in different directions in successive layers. Which type of tissue is this?


Section 3: Muscle Tissue and Neural Tissue


• 4.12 Specify the functions of muscle tissue and neural tissue.

• 4.13 CLINICAL MODULE Describe the roles of inflammation and regeneration in

response to tissue injury.


• Muscle and neural tissue contribute significantly to various systems in the body

• These two tissue types contribute the most (muscle) and least (neural) to body weight

Section 3: Muscle Tissue and Neural Tissue


The relativecontributions of muscletissue and neural tissue tothe weight of the body

The three types of muscle tissue

Muscle Tissue

Skeletal Muscle Tissue

Skeletal muscle tissuemoves the body by pullingon bones of the skeleton,making it possible for usto walk, dance, bite anapple, or play the ukulele.

Cardiac muscle tissuecontractions move bloodthrough the bloodvessels.

Cardiac Muscle Tissue

Smooth muscle tissuecontractions move fluids andsolids along the digestivetract and regulate thediameters of small arteries,among other functions.

Smooth Muscle Tissue

Epithelial tissue3%

Neural tissue 2%

Connective tissue 45%

Muscle tissue 50%


Module 4.12: Muscle tissue for contraction and neural tissue for communication

• Muscle tissue

• All functions involve movement

• Movement of body

• Movement of blood around cardiovascular system

• Movement of materials along digestive tract

• Three types

1. Skeletal muscle tissue

2. Cardiac muscle tissue

3. Smooth muscle tissue


• Muscle tissue

• Three types

1. Skeletal muscle tissue

• Found in skeletal muscle

• Cells are long, cylindrical, banded (striated), and have multiple nuclei (multinucleate)

• Functions

• Move skeleton

• Guard organ entrances for digestive, respiratory, and urinary system

• Generate heat

• Protect internal organs



• Muscle tissue (continued)


2. Cardiac muscle tissue

• Found only in heart

• Cells are short, branched, and have a single nucleus

• Interconnected with special junctions (intercalated discs)

• Functions to move blood and maintain blood pressure



• Muscle tissue (continued)


3. Smooth muscle tissue

• Found throughout body (skin, blood vessel walls, many organs of various systems)

• Cells are short, spindle-shaped, nonstriated, have a single nucleus

• Functions

• Move food, urine, and reproductive secretions

• Control diameter of respiratory passageways and blood vessels


© 2011 Pearson Education, Inc.Figure 4.12 1 - 3

The structure and function of the three types of muscle tissue

Skeletal muscles move or stabilize the position of the skeleton;guard entrances and exits to the digestive, respiratory, andurinary tracts; generate heat; and protect internal organs.

Cardiac muscle moves blood and maintains bloodpressure.

Smooth muscle moves food, urine, and reproductive tract secretions;controls diameter of respiratory passageways and regulates diameter ofblood vessels.

Nuclei

Musclefiber

Striations

Nucleus

Cardiacmuscle cells

Intercalateddiscs

Striations

Smoothmuscle cell

Nucleus

LM x 235

LM x 450

LM x 180


• Neural tissue (nervous tissue)

• Specialized for conduction of electrical impulses

• 98% found in brain and spinal cord

• Two basic types of cells

1. Neurons (neuros, nerve)

2. Neuroglia or glial cells (glia, glue)

• Various supporting cells



• Neurons

• Transfer information around body and perform information processing

• = Conscious and unconscious thought in the brain

• Vary in size and shape

• Longest cells in body are neurons (up to 1 meter)



• Neuron structure

• Dendrites (dendron, tree)

• Receive information

• Axon

• Conducts information to other cells

• Also called nerve fibers

• Cell body

• Contains large nucleus and other organelles

• Cell control center and site of information processing

• Most lack centrioles and cannot divide



The shapes of differenttypes of neuroglia



• Neuroglia

• Several different structural types with associated functions

• Maintain physical structure of neural tissue

• Repair neural tissue framework after injury

• Perform phagocytosis

• Provide nutrients to neurons

• Regulate the composition of the interstitial fluid surrounding neurons


Module 4.12 Review

a. Identify the three types of muscle tissue in the body.

b. Which type of muscle tissue has small, tapering cells with single nuclei and no obvious striations?

c. Irregularly shaped cells with many fibrous projections, some several centimeters long, are probably which type of cell?


Module 4.13 CLINICAL MODULE: Response to injury

• Organs are comprised of different tissue types

• Damage to an organ affects many tissues

• Tissues respond in a coordinated way to restore homeostasis

• Each tissue has a different ability to regenerate

• Epithelial, connective (except cartilage), and smooth muscle regenerate well

• Other muscle types and neural tissue regenerate poorly, if at all

• Scar tissue replaces tissues that do not regenerate (= fibrosis)


• Injury• Exposure to pathogens and toxins (infection)

• Stimulates mast cell activation, which causes inflammation

• Inflammation

• Familiar symptoms of swelling, redness, warmth, and pain

• Occurs in connective tissue

• So can occur anywhere in body because part of all organs

• Leads to increased oxygen/nutrients, phagocytosis, and removal of toxins and wastes



• Regeneration

• Repair after tissue stabilized and inflammation ends

• Fibroblasts secrete collagen fibers to stabilize area (= scar tissue)

• Gradually remodeled or replaced

• Normal conditions restored



The events that occur during tissue injury and repair

Injury

When a tissue is injured, a generaldefense mechanism is activated. Exposure to Pathogens and Toxins

An injured tissue contains anabnormal concentration ofpathogens, toxins, wasteproducts, and the chemicalsfrom injured cells.

Mast Cell Activation

When an injury damagesconnective tissue, mastcells release a variety ofchemicals. This process,called mast cell activation,stimulates inflammation.stimulates

Histamine

Mast cell

Heparin Prostaglandins

Inflammation


Regeneration inhibits mast cell activation

Regeneration

Regeneration, the repair to the injured tissueonce inflammation has subsided.

Normaltissue

conditionsrestored

As tissue conditions return to normal,fibroblasts move into the area, layingdown a network of collagen fibers thatstabilizes the injury site. This processproduces a dense, collagenousframework known as scar tissue. Overtime, scar tissue is usually “remodeled”and gradually assumes a more normalappearance.

Scartissue

Over a period of hours todays, the cleanup processgenerally succeeds ineliminating the inflam-matory stimuli.

Injury

Mast Cell Activation

Inflammation


a. Identify the two processes in the response to tissue injury.

b. What are the four indications of inflammation that occur following an injury?

c. Why can inflammation occur in any organ in the body?

Module 4.13 CLINICAL MODULE: Review

4 Tissue Level of Organization

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