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© 2012 Pearson Education, Inc.
3Foundations:Tissues and Early Embryology
PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska
© 2012 Pearson Education, Inc.
Introduction
• This chapter concentrates on cells and tissues• There are over 75 trillion cells in the body• All cells can be placed into one of the four
tissue categories• Epithelial tissue• Connective tissue• Muscular tissue• Neural tissue
© 2012 Pearson Education, Inc.
Figure 3.1 An Orientation to the Tissues of the Body
MOLECULESATOMS
CELLSEXTRACELLULAR
MATERIALAND FLUIDS
TISSUESwith special functions
ORGANSwith multiple functions
Organic / Inorganic
Combineto form
Interactto form
Thatsecrete
andregulate
Combine to form
Combineto form
ORGAN SYSTEMSChapters 4–27
Interactin
EPITHELIA
CONNECTIVETISSUES
MUSCLE TISSUE
NEURAL TISSUE
• Cover exposed surfaces• Line internal passageways and chambers• Produce glandular secretions See Figures 3.2 to 3.10
• Store energy See Figures 3.11 to 3.19, 3.21
• Contracts to produce active movement See Figure 3.22
• Conducts electrical impulses• Carries information See Figure 3.23
• Fill internal spaces• Provide structural support
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Epithelial Tissue
• Epithelial Tissue Characteristics• Cellularity
• Cells are bound close together• No intercellular space
• Polarity • Have an exposed apical surface• Have an attached basal surface
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Epithelial Tissue
• Epithelial Tissue Characteristics (continued)• Attachment
• Basal layer is attached to the basal lamina
• Avascularity• Do not consist of blood vessels
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Epithelial Tissue
• Epithelial Tissue Characteristics (continued)• Arranged in sheets
• Composed of one or more layers of cells
• Regeneration• Cells are continuously replaced via cell
reproduction
© 2012 Pearson Education, Inc.
Figure 3.2a Polarity of Epithelial CellsCilia
Microvilli
Apicalsurface
Golgiapparatus
Nucleus
Mitochondria
Basal lamina
Basolateralsurfaces
Many epithelial cells differ in internal organization along anaxis between the apical surface and the basal lamina. Theapical surface frequently bears microvilli; less often, it mayhave cilia or (very rarely) stereocilia. A single cell typicallyhas only one type of process; cilia and microvilli are showntogether to highlight their relative proportions. Tightjunctions prevent movement of pathogens or diffusion ofdissolved materials between the cells. Folds of plasmalemmanear the base of the cell increase the surface area exposed tothe basal lamina. Mitochondria are typically concentrated atthe basolateral region, probably to provide energy for thecell’s transport activities.
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Functions of Epithelial Tissue• Provides physical protection• Controls permeability• Provides sensation• Produces secretions
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Specialization of Epithelial Cells• Microvilli
• For absorption and secretion
• Stereocilia• Long microvilli, commonly found in the inner ear
• Ciliated epithelium• Moves substances over the apical surfaces of the
cells
© 2012 Pearson Education, Inc.
Figure 3.2a Polarity of Epithelial CellsCilia
Microvilli
Apicalsurface
Golgiapparatus
Nucleus
Mitochondria
Basal lamina
Basolateralsurfaces
Many epithelial cells differ in internal organization along anaxis between the apical surface and the basal lamina. Theapical surface frequently bears microvilli; less often, it mayhave cilia or (very rarely) stereocilia. A single cell typicallyhas only one type of process; cilia and microvilli are showntogether to highlight their relative proportions. Tightjunctions prevent movement of pathogens or diffusion ofdissolved materials between the cells. Folds of plasmalemmanear the base of the cell increase the surface area exposed tothe basal lamina. Mitochondria are typically concentrated atthe basolateral region, probably to provide energy for thecell’s transport activities.
© 2012 Pearson Education, Inc.
Figure 3.2b Polarity of Epithelial Cells
Cilia
Microvilli
An SEM showing the surface of the epithelium thatlines most of the respiratory tract. The small, bristlyareas are microvilli found on the exposed surfaces ofmucus-producing cells that are scattered among theciliated epithelial cells.
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Maintaining the Integrity of the Epithelium• Three factors involved in maintenance
• Intercellular connections• Attachment to the basal lamina
Lamina lucida: a clear layer of proteins that provides a barrier that restricts the movement of proteins and other large molecules.
Lamina densa: provided by underlying connective tissue and gives strength to basal lamina.
• Epithelial maintenance and renewal is self-perpetuated
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Figure 3.3b Epithelia and Basal Laminae
Basallamina
Clear layerDense layer
CAMsProteoglycans(intercellular cement)Plasmalemma
Connective tissue
At their basal surfaces, epithelia are attached to abasal lamina that forms the boundary between theepithelial cells and the underlying connective tissue.
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Epithelial Tissue
• Classification of Epithelia• Simple
• Epithelium has only one layer of cells
• Stratified • Epithelium has two or more layers of cells
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Epithelial Tissue
• Epithelial Tissue Cells• Squamous cells
• Thin, flat cells / “squished” nuclei
• Cuboidal cells• Cube-shaped cells / centered, round nucleus
• Columnar cells• Longer than they are wide / nucleus near the base
• Transitional cells• Mixture of cells / nuclei appear to be scattered
© 2012 Pearson Education, Inc.
Figure 3.4a Histology of Squamous Epithelia
Simple Squamous Epithelium
Connective tissue
Locations: Mesothelialining ventral body cavi-ties; endothelia liningheart and blood vessels;portions of kidney tubules(thin sections of nephronloops); inner lining ofcornea; alveoli of lungs
Functions: Reducesfriction; controls vesselpermeability; performsabsorption and secretion
A superficial view of the simple squamous epithelium (mesothelium) that lines the peritoneal cavity
Lining of peritoneal cavity
Cytoplasm
Nucleus
LM 238
© 2012 Pearson Education, Inc.
Figure 3.4b Histology of Squamous Epithelia
Stratified Squamous Epithelium
Locations: Surface ofskin; lining of mouth, throat,esophagus, rectum, anus,and vagina
Functions: Provides physicalprotection against abrasion,pathogens, and chemical attack
Sectional views of the stratified squamous epithelium that covers the tongue
Surface of tongue
Stem cells
Basal lamina
Squamoussuperficial cells
Connectivetissue
LM 310
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Figure 3.5a Histology of Cuboidal Epithelia
Simple Cuboidal Epithelium
LOCATIONS: Glands; ducts;portions of kidney tubules; thyroidgland
FUNCTIONS: Limited protection,secretion, absorption
A section through the simple cuboidal epithelium lining a kidney tubule. The diagrammatic view emphasizes structural details that permit the classification of an epithelium as cuboidal.
Connectivetissue
Cuboidalcells
Basallamina
Nucleus
LM 1400
Kidney tubule
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Figure 3.5b Histology of Cuboidal Epithelia
Stratified Cuboidal Epithelium
LM 1413
Lumen of duct
Basal lamina
Nucleus
Connective tissue
Stratifiedcuboidal cells
Sweat gland duct
A sectional view of the stratified cuboidal epithelium lining a sweat gland duct in the skin
FUNCTIONS: Protection, secretion, absorption
LOCATIONS: Lining of some ducts(rare)
© 2012 Pearson Education, Inc.
Figure 3.6a Histology of Columnar Epithelia
Simple Columnar Epithelium
Intestinal lining
A light micrograph showing the characteristics of simple columnar epithelium. In thediagrammatic sketch, note the relationships between the height and width of each cell; the relative size, shape, and location of nuclei; and the distance between adjacent nuclei. Contrast these observations with the corresponding characteristics of simple cuboidal epithelia.
LM 350
Loose connectivetissue
Basal lamina
Nucleus
Cytoplasm
Microvilli
LOCATIONS: Lining ofstomach, intestine, gallbladder,uterine tubes, and collectingducts of kidneys
FUNCTIONS: Protection,secretion, absorption
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Figure 3.6b Histology of Columnar Epithelia
Stratified Columnar Epithelium
Salivary gland duct
FUNCTION: Protection
LOCATIONS: Small areas ofthe pharynx, epiglottis, anus,mammary gland, salivarygland ducts, and urethra
Lumen
A stratified columnar epithelium is sometimes found along large ducts, such as this salivary gland duct. Note the overall height of the epithelium and the location and orientation of the nuclei.
Loose connectivetissue
Deeper basalcells
Superficialcolumnar cells
Cytoplasm
Nuclei
Basal lamina
Lumen
LM 175
© 2012 Pearson Education, Inc.
Figure 3.7a Histology of Pseudostratified Ciliated Columnar and Transitional Epithelia
Pseudostratified ciliated columnar epithelium
Pseudostratified ciliated columnar epithelium. The pseudostratified, ciliated, columnar epithelium of the respiratory tract. Note the uneven layering of the nuclei.
LOCATIONS: Lining ofnasal cavity, trachea, andbronchi; portions of malereproductive tract
FUNCTIONS: Protection,secretion
Trachea
Cilia
Cytoplasm
Nuclei
Basal lamina
Loose connectivetissue
LM 350
© 2012 Pearson Education, Inc.
Figure 3.7b Histology of Pseudostratified Ciliated Columnar and Transitional Epithelia
Transitional epithelium
Transitional epithelium. A sectional view of the transitional epithelium lining the urinary bladder. The cells from an empty bladder are in the relaxed state, while those lining a full urinary bladder show the effects of stretching on the arrangement of cells in the epithelium.
LM 450
LM 450
Epithelium(relaxed)
Basal lamina
Connective tissue andsmooth muscle layers
Relaxed bladder
LOCATIONS: Urinarybladder; renal pelvis;ureters
FUNCTIONS: Permitsexpansion and recoilafter stretching
Basal lamina
Epithelium(stretched)
Stretched bladderConnective tissue andsmooth muscle layers
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Glandular Epithelia• Many epithelia are mixed with gland cells• Types of glands
• Serous glands: secrete watery fluids rich in enzymes
• Mucous glands: secrete glycoproteins (mucins) that absorb water to produce mucus
• Mixed exocrine glands: contain both serous and mucous secretions
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Glandular Epithelia (continued)• Endocrine glands
• Secretions enter into the blood or lymph
• Exocrine glands• Secretions travel through ducts to the epithelial
surface
© 2012 Pearson Education, Inc.
Figure 3.9 A Structural Classification of Simple and Compound Exocrine Glands (Part 1 of 2)
Simple Glands
SIMPLETUBULAR
SIMPLE COILEDTUBULAR
SIMPLE BRANCHEDTUBULAR
SIMPLE ALVEOLAR(ACINAR)
SIMPLE BRANCHEDALVEOLAR
Examples: Examples: Examples: Examples: Examples:
Glandcells
Duct
• Intestinal glands • Merocrine sweat glands
• Gastric glands• Mucous glands of esophagus, tongue, duodenum
• Not found in adult; a stage in development of simple branched glands
• Sebaceous (oil) glands
Those that form blind pockets are alveolar oracinar.
Glands whose glandular cells form tubes aretubular; the tubes may be straight or coiled.
© 2012 Pearson Education, Inc.
Epithelial Tissue
• Glandular Epithelia• Modes of Secretion
• Merocrine secretion• Apocrine secretion• Holocrine secretion
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Epithelial Tissue
• Modes of Secretion• Merocrine Secretion
• Secretions released through exocytosis• Examples:
• Goblet cells of the trachea• Cells in the axilla region regarding sweat
production
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Figure 3.10a Mechanisms of Glandular Secretion
Salivary gland
Secretory vesicle
Golgi apparatus
Nucleus
TEM 2300
In merocrine secretion, secretoryvesicles are discharged at the surfaceof the gland cell through exocytosis.
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Epithelial Tissue
• Modes of Secretion• Apocrine Secretion
• Secretions released via the loss of cytoplasm
• Example: • Cells of the mammary glands for milk secretion
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Figure 3.10b Mechanisms of Glandular Secretion
Mammarygland
Breaksdown
Secretion Regrowth
Apocrine secretion involves the loss of cytoplasm. Inclusions, secretory vesicles, and other cytoplasmiccomponents are shed at the apical surface of the cell. The gland cell then undergoes a period of growth and repair before releasing additional secretions.
Golgi apparatus
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Epithelial Tissue
• Modes of Secretion• Holocrine Secretion
• Secretions released upon bursting of the glandular cells
• Example: • Cells of the sebaceous glands
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Figure 3.10c Mechanisms of Glandular Secretion
Hair
Sebaceousgland
Hair follicle
Cells burst, releasingcytoplasmic contents
Cells produce secretion,increasing in size
Cell division replaceslost cells
Stem cell
Holocrine secretion occurs as superficial gland cells break apart. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells.
© 2012 Pearson Education, Inc.
Connective Tissues
• All connective tissues have three main components:• Specialized cells• Matrix
• The matrix is the collective term for the extracellular component of any connective tissue that is made of protein fibers and the ground substance
Collagen fibers are very long, cylindrical fibers made up of three subunits coiled around one another.
Collagen is the most common and strongest fiber. Reticular fibers are a single unit of collagen proteins. Elastic fibers contain the protein elastin.
© 2012 Pearson Education, Inc.
Connective Tissues
• Functions of Connective Tissue• Establishing the structural framework of the
body• Transporting fluid and dissolved materials• Protecting organs• Supporting, surrounding, and connecting
other tissues• Storing energy• Defending the body from microorganisms
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Connective Tissues
• Classification of Connective Tissue• Connective tissue proper
• Has a matrix of fibers (loose fibers and dense fibers)
• Fluid connective tissue• Has a matrix of liquid (blood and lymph)
• Supporting connective tissue• Has a matrix consisting of a gel or a solid (cartilage
and bone)
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Figure 3.11 A Classification of Connective Tissues
Connective Tissues
Connective Tissue Proper Supporting Connective TissueBlood and Lymph
Loose Dense Blood Lymph Cartilage Bone
Solid,crystallinematrix
Solid, rubberymatrix
• hyaline cartilage
• elastic cartilage
• fibrous cartilage
Containedin lymphoidsystem
Contained in cardiovascularsystem
Fibers denselypacked
Fibers createloose, openframework
• areolar tissue
• adipose tissue• reticular tissue
• dense regular
• dense irregular
• elastic
can be divided into three types
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Connective Tissue Proper
• Connective Tissue Proper• Loose fibers
• Areolar tissue• Adipose tissue• Reticular tissue
• Dense fibers• Dense regular• Dense irregular• Elastic
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Connective Tissue Proper
• Areolar Tissue (details)• Location
• Deep dermis• Between muscles
• Function• Connects skin to muscle
• Matrix• Fibers
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Figure 3.14a Histology of Loose Connective Tissues
Areolar Tissue
Areolar tissue. Note the open framework; all the cells of connective tissue proper are found in areolar tissue.
LOCATIONS: Within and deep to the dermis of skin, and covered by the epithelial lining of the digestive,respiratory, and urinary tracts;between muscles; around bloodvessels, nerves, and around joints
FUNCTIONS: Cushions organs;provides support but permitsindependent movement; phagocytic cells provide defense against pathogens
Areolartissue frompleura
Collagenfibers
Mast cell
Elastic fibers
Adipocyte
Fibrocytes
Macrophage
LM 380
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Connective Tissue Proper
• Adipose Tissue (details)• Location
• Hypodermis• Buttocks, surrounds organs
• Function• Cushion• Insulation
• Matrix• Fibers
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Figure 3.14b Histology of Loose Connective Tissues
Adipose Tissue
Adipose tissue. Adipose tissue is a loose connective tissue dominated by adipocytes. In standard histological views, the cells look empty because their lipid inclusions dissolve during slide preparation.
LM 300
Adipocytes(white adipose cells)
LOCATIONS: Deep to the skin,especially at sides, buttocks,breasts; padding around eyesand kidneys
FUNCTIONS: Provides padding and cushions shocks; insulates(reduces heat loss); stores energy
© 2012 Pearson Education, Inc.
Connective Tissue Proper
• Reticular Tissue (details)• Location
• Liver, spleen, kidney, lymph nodes, tonsils, appendix, bone marrow
• Function• Supporting framework
• Matrix• Fibers
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Figure 3.14c Histology of Loose Connective Tissues
Reticular Tissue
Reticular tissue. Reticular tissue consists of an open framework of reticular fibers. These fibers are usually very difficult to see because of the large numbers of cells organized around them.
LOCATIONS: Liver, kidney, spleen,lymph nodes, and bone marrow
FUNCTIONS: Provides supporting framework
Reticular tissuefrom liver
Reticularfibers
LM 375
© 2012 Pearson Education, Inc.
Connective Tissue Proper
• Dense Regular Connective Tissue (details)• Location
• Tendons, aponeuroses, ligaments• Elastic tissue
• Function• Tendons: connect muscle to bone• Aponeuroses: connect muscle to muscle or covers entire
muscle• Ligaments: connect bone to bone• Elastic: stabilizes the vertebrae• Deep fasciae: which surrounds the muscles.
• Matrix• Fibers
© 2012 Pearson Education, Inc.
Figure 3.15a Histology of Dense Connective Tissues
Dense Regular Connective Tissue
Tendon. The dense regular connective tissue in a tendon consists of densely packed, parallel bundles of collagen fibers. The fibrocyte nuclei can be seen flattened between the bundles. Most ligaments resemble tendons in their histological organization.
LM 440
Collagenfibers
Fibrocytenuclei
LOCATIONS: Between skeletalmuscles and skeleton (tendonsand aponeuroses); betweenbones or stabilizingpositions of internalorgans (ligaments);covering skeletalmuscles; deep fasciae
FUNCTIONS: Provides firm attachment;conducts pull of muscles; reducesfriction between muscles; stabilizes relative positions of bones
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Figure 3.15b Histology of Dense Connective Tissues
Elastic Tissue
Elastic Ligament. Elastic ligaments extend between the vertebrae of the spinalcolumn. The bundles of elastic fibers are fatter than the collagen fiber bundles of a tendon or typical ligament.
LM 887
Fibrocytenuclei
Elasticfibers
LOCATIONS: Between vertebrae of the spinal column (ligamentumflavum and ligamentum nuchae); ligaments supporting penis;ligaments supporting transitional epithelia; in blood vessel walls
FUNCTIONS: Stabilizes positions of vertebrae and penis; cushionsshocks; permits expansion and contraction of organs
© 2012 Pearson Education, Inc.
Connective Tissue Proper
• Dense Irregular Connective Tissue (details)• Location
• Nerve and muscle sheaths
• Function• Provides strength
• Matrix• Fibers
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Figure 3.15c Histology of Dense Connective Tissues
Dense Irregular Connective Tissue
Deep Dermis. The deep portion of the dermis of the skin consists of a thick layer of interwoven collagen fibers oriented in various directions.
LM 111
Collagenfiber
bundles
FUNCTIONS: Provides strength to resist force appliedfrom many directions; helps prevent overexpansionof organs such as the urinary bladder
LOCATIONS: Capsules of visceral organs; periosteaand perichondria; nerve and muscle sheaths; dermis
© 2012 Pearson Education, Inc.
Fluid Connective Tissue
• Blood (details)• Location: circulatory system• Erythrocytes
• Transport oxygen and carbon dioxide
• Leukocytes• Fight infections
• Platelets• Blood clotting
• Matrix• Liquid (plasma)
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Figure 3.16 Formed Elements of the Blood
Red blood cells White blood cells Platelets
Red blood cells areresponsible for thetransport of oxygen(and, to a lesser degree,of carbon dioxide) inthe blood.
Red blood cellsaccount for roughly halfthe volume of wholeblood, and give bloodits color.
White blood cells, or leukocytes(LOO-ko-sıts; leuko-, white), help defend thebody from infection and disease.
Monocytes arerelated to the freemacrophages inother tissues.
Lymphocytes arerelatively rare in theblood, but they arethe dominant celltype in lymph.
Eosinophils and neutrophilsare phagocytes. Basophilspromote inflammation muchlike mast cells in otherconnective tissues.
Eosinophil
Neutrophil
Basophil
The third type of formedelement consists ofmembrane-enclosedpackets of cytoplasmcalled platelets.
These cell fragmentsfunction in the clottingresponse that sealsleaks in diamaged orbroken blood vessels.
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Fluid Connective Tissue
• Lymph (details)• Location
• Lymphoid system
• Lymphocytes• Develop into T cells and B cells (for example)
• Function• Involved with the immune system
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Supporting Connective Tissue
• Supporting Connective Tissue• Cartilage and Bone
• Provide a strong framework that supports rest of body
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Supporting Connective Tissue
• Cartilage• Types of Cartilage:
• Hyaline cartilage: the most common type of cartilage.
• Elastic cartilage• Fibrous cartilage
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Figure 3.18a Histology of the Three Types of Cartilage
Hyaline Cartilage
Hyaline cartilage. Note the translucent matrix and the absence of prominent fibers.
LOCATIONS: Between tips of ribs and bones of sternum; covering bone surfaces at synovial joints; supporting larynx (voice box), trachea, and bronchi; forming part of nasal septum
FUNCTIONS: Provides stiff but somewhat flexible support; reducesfriction between bony surfaces
Chondrocytesin lacunae
Matrix
LM 500
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Figure 3.18b Histology of the Three Types of Cartilage
Elastic Cartilage
Elastic cartilage. The closely packed elastic fibers are visible between the chondrocytes.
LM 358
Chondrocytein lacuna
Elastic fibersin matrix
LOCATIONS: Auricle of external ear; epiglottis; auditory canal; cuneiform cartilages of larynx
FUNCTIONS: Provides support, but tolerates distortion without damage and returns to original shape
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Figure 3.18c Histology of the Three Types of Cartilage
Fibrous Cartilage
Fibrous cartilage. The collagen fibers are extremely dense, and the chondrocytes are relatively far apart.
LM 400
Chondrocytes
Fibrousmatrix
LOCATIONS: Pads within knee joint; between pubic bones ofpelvis; intervertebral discs
FUNCTIONS: Resists compression; prevents bone-to-bonecontact; limits relative movement
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Supporting Connective Tissue
• Bone• Location
• Skeletal system
• Function• Support and strength
• Matrix• Solid (lamellae)
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Figure 3.19 Anatomy and Histological Organization of Bone
Osteon
Osteon LM 375
Canaliculi
Osteocytesin lacunae
Matrix
Central canal
Blood vessels
Fibrouslayer
Cellularlayer
Periosteum
Periosteum
Compact bone
Compactbone
Spongybone
Small vein(contained incentral canal)
CapillaryConcentric
lamellae
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Membranes
• Membranes• Epithelia and connective tissue combine to
form membranes• Each membrane consists of:
• Sheet of epithelial cells• An underlying connective tissue
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Membranes
• Mucous membrane: • Covers the cavities that open to exterior.• Lines digestive, respiratory, urinary and reproductive system.
• Serous membrane:• Lines thoracic and abdominopelvic cavity.• Made of two leyers:
• Parietal layer: lines inside surface of thoracic andabdominopelvic cavity.
• Visceral layer: lines the outer surface of organs in the thoracic and abdominopelvic cavity.
• Synovial membrane:• Lines the joints.
• Cutaneous membrane:• Makes skin.
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Figure 3.20a Membranes
Mucous secretion
Epithelium
Lamina propria(areolar tissue)
Mucous membranesare coated with the secretions of mucousglands. Mucousmembranes line mostof the digestive andrespiratory tracts andportions of the urinaryand reproductive tracts.
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Figure 3.20b Membranes
Transudate
Mesothelium
Areolar tissue
Serous membranes linethe ventral bodycavities (the peritoneal,pleural, and pericardialcavities).
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Figure 3.20c Membranes
Epithelium
Areolar tissue
Dense irregularconnective tissue
The cutaneousmembrane, the skin,covers the outersurface of the body.
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Figure 3.20d Membranes
Articular (hyaline) tissue
Synovial fluid
Capsule
Capillary
Adipocytes
Areolar tissue
Epithelium
Bone
Synovialmembrane
Synovial membranesline joint cavities andproduce the fluid withinthe joint.
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The Connective Tissue Framework of the Body
• Connective tissue creates the internal framework of the body
• Layers of connective tissue connect organs with the rest of the body
• Layers of connective tissue are called fascia• Superficial fascia• Deep fascia• Subserous fascia
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Figure 3.21 The Fasciae
Connective Tissue Framework of Body
Superficial Fascia
Deep Fascia
Subserous Fascia
• Between skin and underlying organs
• Areolar tissue and adipose tissue
• Also known as subcutaneous layer or hypodermis
• Forms a strong, fibrous internal framework
• Dense connective tissue
• Bound to capsules, tendons, ligaments, etc.
• Between serous membranes and deep fascia
• Areolar tissue
Body cavity
Rib
Serousmembrane
Cutaneousmembrane
Skin
Body wall
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Muscle Tissue
• Three types of muscle tissue• Skeletal muscle
• Has striations
• Smooth muscle• Ends of the cells are pointy
• Cardiac muscle• Has intercalated discs
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Muscle Tissue
• Skeletal muscle• Muscles that move the skeleton• Voluntary control
• Smooth muscle• Muscles that line the digestive tract, respiratory
tract, and blood vessels• Involuntary control
• Cardiac muscle• Found in the myometrium of the heart• Muscles cells that contract rhythmically
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Figure 3.22a Histology of Muscle Tissue
Skeletal Muscle Tissue
Cells are long, cylindrical,striated, and multinucleate.
LOCATIONS: Combined with connective tissues and neuraltissue in skeletal muscles
FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, andurinary tracts; generates heat; protects internal organs
Skeletal Muscle Fibers. Note the large fiber size, prominent banding pattern,multiple nuclei, and unbranched arrangement.
Nuclei
Musclefiber
Striations
LM 180
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Figure 3.22c Histology of Muscle Tissue
Smooth Muscle Tissue
Cells are short, spindle-shaped, andnonstriated, with a single, centralnucleus
LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs
FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratorypassageways; regulates diameter of blood vessels
Smooth Muscle Cells. Smooth muscle cells are small and spindle shaped, with a central nucleus. They do not branch, and there are no striations.
LM 235
Nucleus
Smoothmuscle
cell
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Figure 3.22b Histology of Muscle Tissue
Cardiac Muscle Tissue
Nuclei
Striations
Cardiacmuscle
cells
Intercalateddiscs
Cells are short, branched, and striated,usually with a single nucleus; cells areinterconnected by intercalated discs.
LOCATION: Heart
FUNCTIONS: Circulates blood;maintains blood (hydrostatic) pressure
LM 450
Cardiac Muscle Cells. Cardiac muscle cells differ from skeletal muscle fibers in three major ways: size (cardiac muscle cells are smaller), organization (cardiac muscle cells branch), and number of nuclei (a typical cardiac muscle cell has one centrally placed nucleus). Both contain actin and myosin filaments in an organized array that produces the striations seen in both types of muscle cell.
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Neural Tissue
• Neural Tissue• Specialized to conduct electrical signals
through the body• Two types of neural cells
• Neurons are the cells that actually transmit the impulse (electrical signals)
• Neuroglia are the supporting cells of the neural tissue; these cells protect the neurons
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Figure 3.23a Histology of Neural Tissue
Brain
Spinal cord
Cell body
Axon
Nucleus ofneuronNucleolus
Dendrites
Diagrammatic view of a representative neuron
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Figure 3.23b Histology of Neural Tissue
Nuclei ofneuroglia
Cell body
Nucleus ofneuron
Nucleolus
Axon
Dendrites
Neuron cell body LM 600
Histological view of arepresentative neuron
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Tissues, Nutrition, and Aging
• Repair and maintenance become less efficient as one ages
• Hormonal changes and lifestyle changes also affect the functioning of tissues
• Epithelia become thinner and connective tissues become fragile
• Cardiac muscle cells and neural tissue cannot regenerate; therefore, relatively minor damage adds up over time, sometimes causing severe health issues