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Transcript of © 2012 Pearson Education, Inc. Chapter 4: Organization at the Tissue Level Tissues are collections...
© 2012 Pearson Education, Inc.
Chapter 4: Organization at the Tissue Level
Tissues are collections of cells that serve a collective purpose
Collections of tissues form organs
Socrative app – course 701439
?1. What is your name
? 2. Name 4 types of tissue.
© 2012 Pearson Education, Inc.
An Introduction to Tissues
TissuesStructures with discrete structural and
functional properties
Tissues in combination form organs, such as
the heart or liver
Organs can be grouped into 11 organ systems
? 3. List the 11 organ systems
© 2012 Pearson Education, Inc.
4-1 Four Types of Tissue
Tissue Are collections of cells and cell products that
perform specific, limited functions
Four types of tissue
1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
4. Neural tissue
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4-1 Four Types of TissueEpithelial Tissue
Covers exposed surfaces
Lines internal passageways
Forms glands
Connective Tissue Fills internal spaces Supports other tissues Transports materials Stores energy
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4-1 Four Types of TissueMuscle Tissue
Specialized for contraction Skeletal muscle, heart muscle, and walls of
hollow organs
Neural Tissue Carries electrical signals from one part of the
body to another
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4-2 Epithelial Tissue
Epithelia Layers of cells covering internal or external
surfaces
Glands Structures that produce secretions
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4-2 Epithelial Tissue
Characteristics of Epithelia
Cellularity (cell junctions)
** Cell membrane features
Polarity (apical and basal surfaces)
** think apex (top; peak) and basement (below)
Attachment (basement membrane or basal lamina)
Avascularity
Without blood vessels
Regeneration
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Figure 4-1 The Polarity of Epithelial Cells
Cilia
Microvilli
Apicalsurface
Golgiapparatus
Nucleus
Mitochondria
Basement membrane
Basolateralsurfaces
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4-2 Epithelial Tissue
Functions of Epithelial Tissue
1. Provide Physical Protection
2. Control Permeability
3. Provide Sensation
4. Produce Specialized Secretions (glandular
epithelium)
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4-2 Epithelial TissueSpecializations of Epithelial Cells
1. Move fluids over the epithelium (protection)
2. Move fluids through the epithelium (permeability)
3. Produce secretions (protection and messengers)
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? 4. What are 4 functions of
epithelial cell?
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4-2 Epithelial Tissue
Intercellular Connections
Support and communication
CAMs (cell adhesion molecules) Transmembrane proteins
Intercellular cement Proteoglycans
Hyaluronan (hyaluronic acid) Glycosaminoglycans
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4-2 Epithelial Tissue
Intercellular Connections
Cell junctions
Form bonds with other cells or extracellular
material
1. Tight junctions
2. Gap junctions
3. Desmosomes
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Figure 4-2 Cell Junctions
Gapjunctions
Hemidesmosome
Spotdesmosome
ClearlayerDenselayer
Intermediatefilaments
Basementmembrane
Dense area
Embedded proteins(connexons)
Proteoglycans
Cell adhesionmolecules (CAMs)
Terminal web
Adhesion belt
Tight junction
Interlockingjunctional
proteins
Tight junction
Adhesion belt
© 2012 Pearson Education, Inc.
Figure 4-2a Cell Junctions
This is a diagrammatic view of an epithelial cell,showing the major types of intercellularconnections.
Gapjunctions
Hemidesmosome
Spotdesmosome
Terminal web
Adhesion belt
Tight junction
© 2012 Pearson Education, Inc.
4-2 Epithelial Tissue
Tight Junctions Between two plasma membranes
Adhesion belt attaches to terminal web
Prevents passage of water and solutes
Isolates wastes in the lumen (open space
down the center of a tube)
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Figure 4-2b Cell Junctions
Tight junction
Adhesion belt
A tight junction is formed by the fusion of the outer layers of two plasma membranes. Tight junctions prevent the diffusion of fluids and solutes betweenthe cells. A continuous adhesion belt lies deep to the tight junction. This belt is tied to the microfilaments of the terminal web.
Terminal web
Interlockingjunctional
proteins
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4-2 Epithelial Tissue
Gap Junctions Allow rapid communication
Are held together by channel proteins
(junctional proteins, connexons)
Allow ions to pass
Coordinate contractions in heart muscle
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Figure 4-2c Cell Junctions
Embedded proteins(connexons)
Gap junctions permit the free diffusion of ions and small molecules between two cells.
© 2012 Pearson Education, Inc.
4-2 Epithelial Tissue
Desmosomes
CAMs, dense areas, and intercellular cement
Spot desmosomes (“spot weld”)Tie cells together Allow bending and twisting
HemidesmosomesAttach cells to the basal lamina
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Figure 4-2d Cell Junctions
Intermediatefilaments
Dense area
Cell adhesionmolecules (CAMs)
Proteoglycans
A spot desmosome tiesadjacent cells together.
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Figure 4-2e Cell Junctions
ClearlayerDenselayer
Hemidesmosomes attach a cell to extracellular structures, such as the protein fibers in the basement membrane.
Basementmembrane
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? 5. What types of intercellular connections are used to ‘glue’
epithelial cells together?
© 2012 Pearson Education, Inc.
4-2 Epithelial Tissue
Attachment to the Basement Membrane Clear layer (lamina lucida)
Thin layer Secreted by epitheliaBarrier to proteins
Dense layer (lamina densa)Thick fibersProduced by connective tissueStrength and filtration
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4-2 Epithelial Tissue
Epithelial Maintenance and Repair
Epithelia are replaced by division of
germinative cells (stem cells)
Near basement membrane
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4-3 Classification of Epithelia Singular = Epithelium; Plural = Epithelia
Classes of Epithelia
1. Based on shape Squamous epithelia — thin and flat
Cuboidal epithelia — square shaped
Columnar epithelia — tall, slender rectangles
2. Based on layers Simple epithelium — single layer of cells
Stratified epithelium — several layers of cells
© 2012 Pearson Education, Inc.
Table 4-1 Classifying Epithelia
© 2012 Pearson Education, Inc.
Table 4-1 Classifying Epithelia
© 2012 Pearson Education, Inc.
4-3 Classification of EpitheliaSquamous Epithelia
Simple squamous epitheliumAbsorption and diffusion
MesotheliumLines body cavities
EndotheliumLines heart and blood vessels
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Figure 4-3a Squamous Epithelia
Simple Squamous Epithelium
Lining of peritoneal cavityConnective tissue
Nucleus
Cytoplasm
LOCATIONS: Mesothelia lining ventral body cavities; endothelia lining heartand blood vessels; portions of kidney tubules (thin sections of nephron loops); inner lining of cornea; alveoli of lungs
FUNCTIONS: Reduces friction; controls vessel permeability; performsabsorption and secretion
LM 238
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4-3 Classification of EpitheliaSquamous Epithelia
Stratified squamous epitheliumProtects against attacks
Keratin protein adds strength and water resistance
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Figure 4-3b Squamous Epithelia
LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina
FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack
Surface of tongue
Squamoussuperficial cells
Stem cells
Basementmembrane
Connectivetissue
LM 310
Stratified Squamous Epithelium
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4-3 Classification of EpitheliaCuboidal Epithelia
Simple cuboidal epitheliumSecretion and absorption
Stratified cuboidal epitheliaSweat ducts and mammary ducts
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Figure 4-4a Cuboidal and Transitional Epithelia
Simple Cuboidal Epithelium
LOCATIONS: Glands; ducts;portions of kidney tubules; thyroidgland
FUNCTIONS: Limited protection,secretion, absorption
Kidney tubule
Connectivetissue
Nucleus
Cuboidalcells
Basementmembrane
LM 650
© 2012 Pearson Education, Inc.
Figure 4-4b Cuboidal and Transitional Epithelia
LOCATIONS: Lining of some ducts(rare)
FUNCTIONS: Protection, secretion,absorption
LM 500
Lumenof duct
Sweat gland duct
Stratifiedcuboidal
cellsBasementmembrane
Nuclei
Connectivetissue
Stratified Cuboidal Epithelium
© 2012 Pearson Education, Inc.
? 6. What are the major classifications
of epithelial cells?
*** pg 116, 117***
© 2012 Pearson Education, Inc.
4-3 Classification of EpitheliaTransitional Epithelium
Tolerates repeated cycles of stretching and
recoiling and returns to its previous shape
without damage
Appearance changes as stretching occurs
Situated in regions of the urinary system (e.g.,
urinary bladder)
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Figure 4-4c Cuboidal and Transitional Epithelia
Transitional Epithelium
FUNCTIONS: Permitsexpansion and recoilafter stretching
LOCATIONS: Urinarybladder; renal pelvis;ureters
LM 400
Urinary bladder
LM 400
Empty bladder
Epithelium(relaxed)
Connective tissue andsmooth muscle layers
Epithelium(stretched)
Connective tissue andsmooth muscle layers
Basement membrane
Full bladder
Basement membrane
LM 400
© 2012 Pearson Education, Inc.
4-3 Classification of Epithelia
Columnar Epithelia
Simple columnar epithelium
Absorption and secretion
Pseudostratified columnar epithelium
Cilia movement
Stratified columnar epithelium
Protection
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Figure 4-5a Columnar Epithelia
LOCATIONS: Lining ofstomach, intestine, gallbladder,uterine tubes, and collectingducts of kidneys
FUNCTIONS: Protection,secretion, absorption
Simple Columnar Epithelium
Microvilli
Cytoplasm
Intestinal lining
Basementmembrane
Looseconnective tissue LM 350
Nucleus
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Figure 4-5b Columnar Epithelia
LOCATIONS: Lining ofnasal cavity, trachea, andbronchi; portions of malereproductive tract
FUNCTIONS: Protection,secretion, move mucuswith cilia
Pseudostratified Ciliated Columnar Epithelium
Cilia
Trachea
Cytoplasm
Nuclei
Basementmembrane
Looseconnective tissue
LM 350
© 2012 Pearson Education, Inc.
Figure 4-5c Columnar Epithelia
LOCATIONS: Small areas ofthe pharynx, epiglottis, anus,mammary glands, salivarygland ducts, and urethra
FUNCTION: Protection
Stratified Columnar Epithelium
Salivary gland duct
Deeper basalcells
Looseconnective tissue
Superficialcolumnar cells
Cytoplasm
Nuclei
Basementmembrane
LumenLumen
LM 175
© 2012 Pearson Education, Inc.
4-3 Classification of Epithelia
Glandular EpitheliaEndocrine glands
Release hormones Into interstitial fluid
No ducts (adrenal glands, ovaries, testes)
Exocrine glandsProduce secretions
Onto epithelial surfaces
Through ducts (sweat, salivary, mammary)
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4-3 Classification of Epithelia
Glandular Epithelia
Modes of Secretion
1. Merocrine secretion
2. Apocrine secretion
3. Holocrine secretion
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4-3 Classification of Epithelia Merocrine Secretion
Produced in Golgi apparatus Released by vesicles (exocytosis) For example, sweat glands
Apocrine Secretion Produced in Golgi apparatus Released by shedding cytoplasm For example, mammary glands
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4-3 Classification of Epithelia
Holocrine Secretion Released by cells bursting, killing gland cells
Gland cells replaced by stem cells
For example, sebaceous glands
© 2012 Pearson Education, Inc.
Figure 4-6a Modes of Glandular Secretion
Salivary gland
Mammary gland
Hair
Sebaceousgland
Hair follicle
Merocrine. In merocrine secretion, secretory vesicles are discharged at the apical surface of the gland cell by exocytosis.
Secretoryvesicle
Golgiapparatus
Nucleus
TEM 3039
© 2012 Pearson Education, Inc.
Figure 4-6c Modes of Glandular Secretion
Salivary gland
Mammary gland
Hair
Sebaceousgland
Hair follicle
Stem cell
Holocrine. Holocrine secretion occurs as superficial gland cells burst. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells.
Cell division replaceslost cells
Cells produce secretion,increasing in size
Cells burst, releasingcytoplasmic contents
© 2012 Pearson Education, Inc.
4-3 Classification of EpitheliaGlandular Epithelia
Types of SecretionsSerous glands
Watery secretions
Mucous glands Secrete mucins
Mixed exocrine glands Both serous and mucous
© 2012 Pearson Education, Inc.
4-3 Classification of EpitheliaGlandular Epithelia
Gland StructureUnicellular glands
Mucous (goblet) cells are the only unicellular exocrine glands
Scattered among epithelia
For example, in intestinal lining
© 2012 Pearson Education, Inc.
4-3 Classification of Epithelia
Gland Structure Multicellular glands
1. Structure of the duct Simple (undivided) Compound (divided)
2. Shape of secretory portion of the gland Tubular (tube shaped) Alveolar or acinar (blind pockets)
3. Relationship between ducts and glandular areas Branched (several secretory areas sharing one duct)
© 2012 Pearson Education, Inc.
Figure 4-7 A Structural Classification of Exocrine Glands
SIMPLE GLANDS
Glandcells
SIMPLETUBULAR
SIMPLE COILEDTUBULAR
Examples:
Examples:
Examples:• Intestinal glands • Merocrine sweat
stage in developmentof simple branchedglands
SIMPLE BRANCHEDTUBULAR
Examples:• Gastric glands• Mucous glands
• Not found in adult; a
SIMPLE ALVEOLAR(ACINAR)
SIMPLE BRANCHEDALVEOLAR
Examples:• Sebaceous (oil)
glandsof esophagus,tongue, duodenum
glands
Duct
© 2012 Pearson Education, Inc.
Figure 4-7 A Structural Classification of Exocrine Glands
COMPOUND GLANDS
COMPOUNDTUBULAR
COMPOUND ALVEOLAR(ACINAR)
COMPOUND TUBULOALVEOLAR
Examples:• Mucous glands (in mouth)
Examples:
• Bulbo-urethral glands (inmale reproductive system)
tubules)
• Mammary glandsExamples:
• Salivary glands• Glands of respiratory
passages• Testes (seminiferous• Pancreas