copyright © 2010 pearson education, inc. chapter 4 tissue

Copyright © 2010 Pearson Education, Inc.

Chapter 4 Tissue


Tissues

• Groups of cells similar in structure and function

• Types of tissues

• Epithelial tissue

• Connective tissue

• Muscle tissue

• Nerve tissue


Epithelial Tissue (Epithelium)

• Two main types (by location):

1. Covering and lining epithelia

• On external and internal surfaces

2. Glandular epithelia

• Secretory tissue in glands


Characteristics of Epithelial Tissue

1. Cells have polarity—apical (upper, free) and basal (lower, attached) surfaces

• Microvilli/cilia – apical surface

• Noncellular basal lamina – selective filter and scaffolding


Characteristics of Epithelial Tissue

2. Are composed of closely packed cells

• Continuous sheets held together by tight junctions and desmosomes

3. Supported by a connective tissue layer - reticular lamina (under the basal lamina)

4. Avascular but innervated

5. High rate of regeneration


Classification of Epithelia

• Two names

1. Layers

1 = simple epithelium

>1 = stratified epithelium

2. Cell Type

• Squamous

• Cuboidal

• Columnar

• (If stratified, name according to apical layer of cells)

Copyright © 2010 Pearson Education, Inc. Figure 4.2a

Stratified

Simple

Apical surface

Basal surface

Apical surface

Basal surface

(a) Classification based on number of cell layers.

Copyright © 2010 Pearson Education, Inc. Figure 4.2b

Squamous

Cuboidal

Columnar(b) Classification based on cell shape.


Overview of Epithelial Tissues

• For each of the following types of epithelia, note:

• Description

• Function

• Location


(a) Simple squamous epithelium

Description: Single layer of flattenedcells with disc-shaped central nucleiand sparse cytoplasm; the simplestof the epithelia.

Function: Allows passage ofmaterials by diffusion and filtrationin sites where protection is notimportant; secretes lubricatingsubstances in serosae.

Location: Kidney glomeruli; air sacsof lungs; lining of heart, bloodvessels, and lymphatic vessels; liningof ventral body cavity (serosae).

Photomicrograph: Simple squamous epitheliumforming part of the alveolar (air sac) walls (125x).

Air sacs oflung tissue

Nuclei ofsquamousepithelialcells


Epithelia: Simple Squamous

• Two other locations

• Endothelium

• The lining of lymphatic vessels, blood vessels, and heart

• Friction reducing tissue

• Mesothelium

• The epithelium of serous membranes in the ventral body cavity


(b) Simple cuboidal epithelium

Description: Single layer ofcubelike cells with large,spherical central nuclei.

Function: Secretion andabsorption.

Location: Kidney tubules;ducts and secretory portionsof small glands; ovary surface.

Photomicrograph: Simple cuboidalepithelium in kidney tubules (430x).

Basementmembrane

Connectivetissue

Simplecuboidalepithelialcells

Copyright © 2010 Pearson Education, Inc. Figure 4.3c

(c) Simple columnar epithelium

Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells).

Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.

Location: Nonciliated type lines most of the digestive tract (stomach to anal canal),gallbladder, and excretory ducts of someglands; ciliated variety lines small bronchi, uterine tubes, and some regionsof the uterus.

Photomicrograph: Simple columnar epitheliumof the stomach mucosa (860X).

Simplecolumnarepithelialcell

Basementmembrane

Copyright © 2010 Pearson Education, Inc. Figure 4.3d

(d) Pseudostratified columnar epithelium

Description: Single layer of cells ofdiffering heights, some not reachingthe free surface; nuclei seen atdifferent levels; may contain mucus-secreting cells and bear cilia.

Function: Secretion, particularly ofmucus; propulsion of mucus byciliary action.

Location: Nonciliated type in male’ssperm-carrying ducts and ducts oflarge glands; ciliated variety linesthe trachea, most of the upperrespiratory tract.

Photomicrograph: Pseudostratified ciliatedcolumnar epithelium lining the human trachea (570x).

Trachea

Cilia

Pseudo-stratifiedepitheliallayer

Basementmembrane

Mucus ofmucous cell

Copyright © 2010 Pearson Education, Inc. Figure 4.3e

(e) Stratified squamous epithelium

Description: Thick membranecomposed of several cell layers;basal cells are cuboidal or columnarand metabolically active; surfacecells are flattened (squamous); in thekeratinized type, the surface cells arefull of keratin and dead; basal cellsare active in mitosis and produce thecells of the more superficial layers.

Function: Protects underlyingtissues in areas subjected to abrasion.

Location: Nonkeratinized type formsthe moist linings of the esophagus,mouth, and vagina; keratinized varietyforms the epidermis of the skin, a drymembrane.

Photomicrograph: Stratified squamous epitheliumlining the esophagus (285x).

Stratifiedsquamousepithelium

Nuclei

Basementmembrane

Connectivetissue


Epithelia: Stratified Cuboidal

• Quite rare in body

• Found in some sweat and mammary glands

• Typically two cell layers thick


Epithelia: Stratified Columnar

• Limited distribution in body

• Small amounts in pharynx, male urethra, and lining some glandular ducts

• Also occurs at transition areas between two other types of epithelia

Copyright © 2010 Pearson Education, Inc. Figure 4.3f

(f) Transitional epithelium

Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells domeshaped or squamouslike, depending on degree of organ stretch.

Function: Stretches readily and permits distension of urinary organ by contained urine.

Location: Lines the ureters, urinary bladder, and part of the urethra.

Photomicrograph: Transitional epithelium lining the urinary bladder, relaxed state (360X); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and become elongated when the bladder is filled with urine.

BasementmembraneConnectivetissue

Transitionalepithelium


Glandular Epithelia

• A gland is one or more cells that makes and secretes an aqueous fluid

• Classified by:

• Site of product release—endocrine or exocrine

• Relative number of cells forming the gland—unicellular (e.g., goblet cells) or multicellular


Endocrine Glands

• Ductless glands

• Secrete hormones that travel through lymph or blood to target organs

• Secrete by exocytosis into the extracellular space

• Most are multicellular

• Ex. Pituitary, pancreas, ovaries, testes, thyroid, and adrenal glands


Exocrine Glands

• More numerous than endocrine glands

• Secretions released onto body surfaces (skin) or into body cavities

• Examples include mucous (unicellular), sweat, oil, and salivary glands


Multicellular Exocrine Glands

• Multicellular exocrine glands are composed of a duct and a secretory unit

• Classified according to:

• Duct type (simple or compound)

• Structure of their secretory units (tubular, alveolar, or tubuloalveolar)

Copyright © 2010 Pearson Education, Inc. Figure 4.5

Compound duct structure(duct branches)

Simple tubular

ExampleIntestinal glands

Simple branchedtubular

ExampleStomach (gastric)glands

Compound tubular

ExampleDuodenal glands of small intestine

Compound alveolar

ExampleMammary glands

Simplealveolar

ExampleNo importantexample in humans

Simple branchedalveolar

ExampleSebaceous (oil)glands

Compoundtubuloalveolar

ExampleSalivary glands

Tubularsecretorystructure

Alveolarsecretorystructure

Surface epithelium Duct Secretory epithelium

Simple duct structure(duct does not branch)


Modes of Secretion

• Merocrine

• Products are secreted by exocytosis (e.g., pancreas, sweat and salivary glands)

• Holocrine

• Products are secreted by rupture of gland cells (e.g., sebaceous glands)

• Sebaceous cyst


Connective Tissue

• Most abundant and widely distributed tissue type

• Four classes

• Connective tissue proper

• Cartilage

• Bone tissue

• Blood


Major Functions of Connective Tissue

• Binding and support

• Protection

• Insulation

• Transportation (blood)


Characteristics of Connective Tissue

• Connective tissues have:

• Common origin

• Varying degrees of vascularity

• Extracellular matrix


Structural Elements of Connective Tissue

• Ground substance

• Medium through which solutes diffuse between blood capillaries and cells

• Components:

• Interstitial fluid

• Adhesion proteins (“glue”)

• Proteoglycans – contain chrondroitin sulfate and hyaluronic acid



• Three types of fibers

• Collagen (white fibers)

• Strongest and most abundant type

• Provides high tensile strength

• Elastic

• Networks of long, thin, elastin fibers that allow for stretch

• Reticular

• Short, fine, highly branched collagenous fibers



• Cells

• Mitotically active and secretory cells = “blasts”

• Mature cells = “cytes”

• Fibroblasts in connective tissue proper

• Chondroblasts and chondrocytes in cartilage

• Osteoblasts and osteocytes in bone

• Hematopoietic stem cells in bone marrow

• Fat cells, white blood cells, mast cells, and macrophages


Connective Tissue Proper

• Types:

• Loose connective tissue

• Areolar

• Adipose

• Reticular

• Dense connective tissue

• Dense regular

• Dense irregular

• Elastic


(a) Connective tissue proper: loose connective tissue, areolar

Description: Gel-like matrix with allthree fiber types; cells: fibroblasts,macrophages, mast cells, and somewhite blood cells.

Function: Wraps and cushionsorgans; its macrophages phagocytizebacteria; plays important role ininflammation; holds and conveystissue fluid.

Location: Widely distributed underepithelia of body, e.g., forms laminapropria of mucous membranes;packages organs; surroundscapillaries.

Photomicrograph: Areolar connective tissue, asoft packaging tissue of the body (300x).

Epithelium

Laminapropria

Fibroblastnuclei

Elasticfibers

Collagenfibers

Figure 4.8a


(b) Connective tissue proper: loose connective tissue, adipose

Description: Matrix as in areolar,but very sparse; closely packedadipocytes, or fat cells, havenucleus pushed to the side by largefat droplet.

Function: Provides reserve foodfuel; insulates against heat loss;supports and protects organs.

Location: Under skin in thehypodermis; around kidneys andeyeballs; within abdomen; in breasts.

Photomicrograph: Adipose tissue from thesubcutaneous layer under the skin (350x).

Nucleus offat cell

Vacuolecontainingfat droplet

Adiposetissue

Mammaryglands


(c) Connective tissue proper: loose connective tissue, reticular

Description: Network of reticularfibers in a typical loose groundsubstance; reticular cells lie on thenetwork.

Function: Fibers form a soft internalskeleton (stroma) that supports othercell types including white blood cells,mast cells, and macrophages.

Location: Lymphoid organs (lymphnodes, bone marrow, and spleen).

Photomicrograph: Dark-staining network of reticularconnective tissue fibers forming the internal skeletonof the spleen (350x).

Spleen

White bloodcell(lymphocyte)

Reticularfibers

Copyright © 2010 Pearson Education, Inc. Figure 4.8d

(d) Connective tissue proper: dense connective tissue, dense regular

Description: Primarily parallelcollagen fibers; a few elastic fibers;major cell type is the fibroblast.

Function: Attaches muscles tobones or to muscles; attaches bonesto bones; withstands great tensilestress when pulling force is appliedin one direction.

Location: Tendons, mostligaments, aponeuroses.

Photomicrograph: Dense regular connectivetissue from a tendon (500x).

Shoulderjoint

Ligament

Tendon

Collagenfibers

Nuclei offibroblasts

Copyright © 2010 Pearson Education, Inc. Figure 4.8e

(e) Connective tissue proper: dense connective tissue, dense irregular

Description: Primarilyirregularly arranged collagenfibers; some elastic fibers;major cell type is the fibroblast.

Function: Able to withstandtension exerted in manydirections; provides structuralstrength.

Location: Fibrous capsules oforgans and of joints; dermis ofthe skin; submucosa ofdigestive tract.

Photomicrograph: Dense irregularconnective tissue from the dermis of theskin (400x).

Collagenfibers

Nuclei offibroblasts

Fibrousjointcapsule

Copyright © 2010 Pearson Education, Inc. Figure 4.8f

(f) Connective tissue proper: dense connective tissue, elastic

Description: Dense regularconnective tissue containing a highproportion of elastic fibers.

Function: Allows recoil of tissuefollowing stretching; maintainspulsatile flow of blood througharteries; aids passive recoil of lungsfollowing inspiration.

Location: Walls of large arteries;within certain ligaments associatedwith the vertebral column; within thewalls of the bronchial tubes.

Elastic fibers

Aorta

HeartPhotomicrograph: Elastic connective tissue inthe wall of the aorta (250x).


Connective Tissue: Cartilage

• Three types of cartilage:

• Hyaline cartilage

• Elastic cartilage

• Fibrocartilage

Copyright © 2010 Pearson Education, Inc. Figure 4.8g

(g) Cartilage: hyaline

Description: Amorphous but firmmatrix; collagen fibers form animperceptible network; chondroblastsproduce the matrix and when mature(chondrocytes) lie in lacunae.

Function: Supports and reinforces;has resilient cushioning properties;resists compressive stress.

Location: Forms most of theembryonic skeleton; covers the endsof long bones in joint cavities; formscostal cartilages of the ribs; cartilagesof the nose, trachea, and larynx.

Photomicrograph: Hyaline cartilage from thetrachea (750x).

Costalcartilages

Chondrocytein lacuna

Matrix

Copyright © 2010 Pearson Education, Inc. Figure 4.8h

(h) Cartilage: elastic

Description: Similar to hyalinecartilage, but more elastic fibersin matrix.

Function: Maintains the shapeof a structure while allowinggreat flexibility.

Location: Supports the externalear (pinna); epiglottis.

Photomicrograph: Elastic cartilage fromthe human ear pinna; forms the flexibleskeleton of the ear (800x).

Chondrocytein lacuna

Matrix

Copyright © 2010 Pearson Education, Inc. Figure 4.8i

(i) Cartilage: fibrocartilage

Description: Matrix similar tobut less firm than that in hyalinecartilage; thick collagen fiberspredominate.

Function: Tensile strengthwith the ability to absorbcompressive shock.

Location: Intervertebral discs;pubic symphysis; discs of kneejoint.

Photomicrograph: Fibrocartilage of anintervertebral disc (125x). Special stainingproduced the blue color seen.

Intervertebraldiscs

Chondrocytesin lacunae

Collagenfiber

Copyright © 2010 Pearson Education, Inc. Figure 4.8j

(j) Others: bone (osseous tissue)

Description: Hard, calcifiedmatrix containing many collagenfibers; osteocytes lie in lacunae.Very well vascularized.

Function: Bone supports andprotects (by enclosing);provides levers for the musclesto act on; stores calcium andother minerals and fat; marrowinside bones is the site for bloodcell formation (hematopoiesis).Location: Bones

Photomicrograph: Cross-sectional viewof bone (125x).

Lacunae

Lamella

Centralcanal

Copyright © 2010 Pearson Education, Inc. Figure 4.8k

(k) Others: blood

Description: Red and whiteblood cells in a fluid matrix(plasma).

Function: Transport ofrespiratory gases, nutrients,wastes, and other substances.

Location: Contained withinblood vessels.

Photomicrograph: Smear of human blood (1860x); twowhite blood cells (neutrophil in upper left and lymphocytein lower right) are seen surrounded by red blood cells.

Neutrophil

Red bloodcells

Lymphocyte

Plasma


Nervous Tissue

• Main component of the brain, spinal cord, and nerves

• Makes the structures that control and regulate the body functions

• High conductive properties

Copyright © 2010 Pearson Education, Inc. Figure 4.9

Photomicrograph: Neurons (350x)

Function: Transmit electricalsignals from sensory receptorsand to effectors (muscles andglands) which control their activity.

Location: Brain, spinalcord, and nerves.

Description: Neurons arebranching cells; cell processesthat may be quite long extend fromthe nucleus-containing cell body;also contributing to nervous tissueare nonirritable supporting cells(not illustrated).

Dendrites

Neuron processes Cell body

Axon

Nuclei ofsupportingcells

Cell bodyof a neuron

Neuronprocesses

Nervous tissue


Muscle Tissue

• Highly cellular and vascularized tissue

• Contain myofilaments – actin and myosin – responsible for muscular movement


(a) Skeletal muscle

Description: Long, cylindrical,multinucleate cells; obviousstriations.

Function: Voluntary movement;locomotion; manipulation of theenvironment; facial expression;voluntary control.

Location: In skeletal musclesattached to bones oroccasionally to skin.

Photomicrograph: Skeletal muscle (approx. 460x).Notice the obvious banding pattern and thefact that these large cells are multinucleate.

Nuclei

Striations

Part ofmuscle fiber (cell)


(b) Cardiac muscle

Description: Branching, striated, generally uninucleate cells that interdigitate atspecialized junctions (intercalated discs).

Function: As it contracts, it propels blood into the circulation; involuntary control.Location: The walls of the heart.

Photomicrograph: Cardiac muscle (500X);notice the striations, branching of cells, andthe intercalated discs.

Intercalateddiscs

Striations

Nucleus


(c) Smooth muscle

Description: Spindle-shapedcells with central nuclei; nostriations; cells arranged closely to form sheets.

Function: Propels substancesor objects (foodstuffs, urine,a baby) along internal passage-ways; involuntary control.Location: Mostly in the wallsof hollow organs.

Photomicrograph: Sheet of smooth muscle (200x).

Smoothmusclecell

Nuclei


Membranes and Linings

• Cutaneous membrane (skin)

• Mucous mebrane – line cavities open to the outside

• Serous membranes – moist membrane found in closed ventral cavities

• Plueral serosae line internal body walls

• Visceral serosae cover internal organs


Steps in Tissue Repair

• Inflammation

• Release of inflammatory chemicals

• Dilation of blood vessels

• Increase in vessel permeability

• Clotting occurs



• Organization and restored blood supply

• The blood clot is replaced with granulation tissue

• Epithelium begins to regenerate

• Fibroblasts produce collagen fibers to bridge the gap

• Debris is phagocytized



• Regeneration and fibrosis

• The scab detaches

• Fibrous tissue matures; epithelium thickens and begins to resemble adjacent tissue

• Results in a fully regenerated epithelium with underlying scar tissue

copyright © 2010 pearson education, inc. chapter 4 tissue

Documents

pearson education

epithelial tissue epithelium

simple epithelium

tissue mesothelium

scaffolding slide

stratified epithelium

apical layer of cells

c c simple columnar