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The Tissue Level of Organization
Chapter 3
Tissue
• Definition – an aggregation of cells in which each cooperates with all others in the performance of a given function
• Examples of general functions – Movement – Protection – Support – Production of chemicals
Principal Tissue Types
• Epithelial • Connective • Muscular • Nervous
Human Anatomy, 3rd edition Prentice Hall, © 2001
Epithelial Tissue • Functions
– Coverings and linings – Forms glands
• Characteristics – Closely packed cells – Basement membrane – Nerves – Avascular – Cell growth and
replacement by mitosis • Classification
– Simple or stratified – Squamous, cuboidal,
columnar, or transitional
Epithelia of Coverings and Linings
Human Anatomy, 3rd edition Prentice Hall, © 2001
Squamous Epithelium
• Simple Squamous Epithelium – Highly adapted to
diffusion, osmosis, & filtration
• Stratified Squamous Epithelium – Surface layer is flat – Function -
protection
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Human Anatomy, 3rd edition Prentice Hall, © 2001
Cuboidal Epithelium • Simple cuboidal
epithelium • Lines glands and
their ducts • Function –
secretion and absorption
• Stratified Cuboidal epithelium – Surface layer
cube-shaped – Function –
protection
Transitional Epithelium
• Can be stretched • Lines hollow
structures that expand
• Function – prevents rupture of organ
http://www.mhhe.com/biosci/ap/histology_mh/stratepi.html
Human Anatomy, 3rd edition Prentice Hall, © 2001
Columnar Epithelia • Simple columnar
epithelium – Functions –
protection, absorption, secretion
• Pseudostratified columnar epithelium – Appear stratified but
all cells connect to the basal lamina
– Functions – protection, secretion
Pseudostratified Columnar Epithelium
• Appear stratified but all cells connect to the basal lamina
• Functions – protection, secretion
Glandular Epithelium • Gland – 1 or more cells
– Unicellular gland – goblet cell – Multicellular – secretory sheets or groups of cells
• Serous • Mucous • Mixed • Cytogenic
• Function – secretion • Types
– Exocrine – to surface or ducts – Endocrine – to blood
Human Anatomy, 3rd edition Prentice Hall, © 2001
Mechanisms of Glandular Secretion • Merocrine
– Secretion is released by exocytosis
• Apocrine – Residual name – Mainly merocrine – Secretion is released
by pinching off of vesicles
• Holocrine – Secretion is released
by entire cell bursting
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Connective Tissue
• Most abundant tissue • Functions are varied • Characteristics
– Specialized cells, widely scattered – Rich blood supply – Much matrix
• Extracellular fibers • Ground substance
Human Anatomy, 3rd edition Prentice Hall, © 2001
Classification of Connective Tissues • Embryonic
– Mesenchymal cells • Adult connective tissues
Human Anatomy, 3rd edition Prentice Hall, © 2001
Embryonic Connective Tissues Cell Types Found in Connective Tissue
• Fibroblasts – Secrete the molecules that form the matrix
• Ground substance – Water and glycoproteins
• Fibers – Fixed cells
• Fibrocytes • Macrophages
– “Big eaters” – May be fixed or wandering
Additional Connective Tissue Cells • Adipocytes
– Fixed fat cells • Mesenchymal cells
– Fixed cells that can divide (mitosis) to replace damaged connective tissue
• Melanocytes – Fixed cells that store melanin
• Lymphocytes – Wandering immune system cells
• Mast cells – Around blood vessels – Wandering cells that produce histamine & heparin
Connective Tissue Fibers • Collagen fibers
– Most common type – White – Strong, ropelike – Form ligaments, tendons
• Reticular fibers – Thin – Woven into rough, flexible network
• Elastic fibers – Yellow – Thin – Stretch
• Contain elastin
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Types of Connective Tissue
Human Anatomy, 3rd edition Prentice Hall, © 2001
Loose (Areolar) Connective Tissue
• Fibers not abundant • Binds epithelia to deeper
tissue • Contains all 3 types of fibers • Examples of locations
– Between skin and muscles – Around digestive tract – Around blood vessels
Human Anatomy, 3rd edition Prentice Hall, © 2001
Adipose Tissue
• Most of the volume is adipocytes
• Provides padding, slows heat loss, food reserve
• Locations – Wherever there is loose
connective tissue
Human Anatomy, 3rd edition Prentice Hall, © 2001
Reticular Tissue
• Reticular fibers form a strong network
• Provides strength and support – Lymphatic organs
• Forms the framework (stroma) of many organs
• Binds together cells of smooth muscle
Dense Connective Tissue
• Types – Dense Regular Connective Tissue – Dense Irregular Connective Tissue – Elastic Connective Tissue
Human Anatomy, 3rd edition Prentice Hall, © 2001
Dense Regular Connective Tissue
• Lots of collagen fibers in bundles
• Cells – fibroblasts in rows between bundles
• Examples – Tendons, ligaments
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Human Anatomy, 3rd edition Prentice Hall, © 2001
Dense Irregular Connective Tissue • Random
arrangement of fibers – Resists stress
• Occurs in sheets • Locations
– Periosteum – Perichondrium – Fibrous capsules of
some organs – Dermis
Human Anatomy, 3rd edition Prentice Hall, © 2001
Elastic Tissue • Lots of elastic fibers • Fibroblasts in spaces between fibers • Provides stretch and strength
Cartilage
• Dense network of collagenous fibers & elastic fibers in a gel-like substance
• Avascular • Cells – chondrocytes in lacunae
– Chondroblasts • Perichondrium – surrounds surface of
cartilage • Growth
– Interstitial growth – Appositional growth
Growth of Cartilage
Types of Cartilage
• Hyaline cartilage • Fibrocartilage • Elastic cartilage
Human Anatomy, 3rd edition Prentice Hall, © 2001
Hyaline Cartilage
• Most common • Provides flexibility
and support • Locations
– Ends of bones – Trachea – Larynx – Embryonic skeleton
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Human Anatomy, 3rd edition Prentice Hall, © 2001
Fibrocartilage • Visible collagenous fibers
with scattered chondrocytes
• Provides strength and rigidity
• Locations – Intervertebral discs – Symphysis pubis
Human Anatomy, 3rd edition Prentice Hall, © 2001
Elastic Cartilage
• Threadlike network of elastic fibers with chondrocytes
• Provides strength and maintains shape
• Locations – Pinna – Eustacian tube
Human Anatomy, 3rd edition Prentice Hall, © 2001
Bone • Solid matrix • Cells
– Osteocytes in lacunae
• Central canal (Haversian canal)
• Lamellae • Osteon (Haversian
system) • Canaliculi • Periosteum
Human Anatomy, 3rd edition Prentice Hall, © 2001
Blood • Functions
– Transport medium – Regulation – Protection
• Composition – Plasma – fluid – Formed elements –
cells & cell fragments • Erythrocyte • Leukocyte • Thrombocyte
Human Anatomy, 3rd edition Prentice Hall, © 2001
A Red Blood Cell
Human Anatomy, 3rd edition Prentice Hall, © 2001
SEM of RBCs
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Human Anatomy, 3rd edition Prentice Hall, © 2001
Membranes • Epithelial layer +
underlying connective tissue = epithelial membrane
• Types – Mucous membrane – Serous membrane – Cutaneous
membrane – Synovial
membrane – Endothelium
Fascia
• Fascia – collective term for sheets of connective tissue
• Functions – Provide strength and stability – Maintain positions of internal organs – Provide a route for the distribution of blood
vessels, lymphatics, and nerves • 3 types
Human Anatomy, 3rd edition Prentice Hall, © 2001
Types of Fascia • Superficial Fascia
– Adipose tissue and loose connective tissue
– Immediately deep to the skin
• Deep Fascia – Dense connective
tissue – Strong internal
framework • Subserous Fascia
– Loose connective tissue
– Between deep fascia and serous membranes
Muscular Tissue
• Specialized cells • Function - contraction • 3 types
– Skeletal muscle – Cardiac muscle – Smooth muscle
Human Anatomy, 3rd edition Prentice Hall, © 2001
Skeletal Muscle
• Connected to bones • Striated • Multinucleated • Voluntary
Human Anatomy, 3rd edition Prentice Hall, © 2001
Cardiac Muscle
• Found in the heart • Striations • Branched cells • Intercalated discs • Involuntary
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Human Anatomy, 3rd edition Prentice Hall, © 2001
Smooth Muscle
• Found in walls of internal organs
• Nonstriated • Involuntary
Human Anatomy, 3rd edition Prentice Hall, © 2001
Nervous Tissue
• Specialized cells • Function – conduction of
electrical impulses • Cells
– Neurons • Neurosoma • Axon • Dendrites
– Neuroglia