Transcript Tissues


Tissues
o Structures with discrete structural and functional properties
o Tissues in combination form organs, such as the heart or liver
o Organs can be grouped into 11 organ systems
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Tissue
o
Are collections of cells and cell products that perform specific,
limited functions
o
Four types of tissue
1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
4. Neural tissue
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 Epithelial
Tissue
o
Covers exposed surfaces
o
Lines internal passageways
o
Forms glands
 Connective
Tissue
o
Fills internal spaces
o
Supports other tissues
o
Transports materials
o
Stores energy
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Muscle Tissue
o
Specialized for contraction
o
Skeletal muscle, heart muscle, and walls of hollow organs
Neural Tissue
o
Carries electrical signals from one part of the body to another
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Epithelia
o
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Layers of cells covering internal or external surfaces
Glands
o
Structures that produce secretions
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Characteristics of Epithelia
o
Cellularity (cell junctions)
o
Polarity (apical and basal surfaces)
o
Attachment (basement membrane or basal lamina)
o
Avascularity
o
Regeneration
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Cilia
Microvilli
Apical
surface
Golgi
apparatus
Nucleus
Mitochondria
Basement membrane
Basolateral
surfaces
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Functions of Epithelial Tissue
1.
Provide Physical Protection
2.
Control Permeability
3.
Provide Sensation
4.
Produce Specialized Secretions (glandular epithelium)
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Specializations of Epithelial Cells
1.
Move fluids over the epithelium (protection)
2.
Move fluids through the epithelium (permeability)
3.
Produce secretions (protection and messengers)
Polarity
1. Apical surfaces
• Microvilli increase absorption or secretion
• Cilia (ciliated epithelium) move fluid
2. Basolateral surfaces
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Maintaining the Integrity of Epithelia
1.
Intercellular connections
2.
Attachment to the basement membrane
3.
Epithelial maintenance and repair
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Intercellular Connections
o
Cell junctions
• Form bonds with other cells or extracellular material
1. Tight junctions
2. Gap junctions
3. Desmosomes
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Attachment to the Basement Membrane
o
Clear layer (lamina lucida)
• Thin layer
• Secreted by epithelia
• Barrier to proteins
o
Dense layer (lamina densa)
• Thick fibers
• Produced by connective tissue
• Strength and filtration
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Tight junction
Adhesion belt
Terminal web
Spot
desmosome
Gap
junctions
Hemidesmosome
This is a diagrammatic view of an epithelial cell,
showing the major types of intercellular
connections.
Interlocking
junctional
proteins
Tight junction
Terminal web
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 between
the cells. A continuous adhesion belt lies
deep to the tight junction. This belt is tied
to the microfilaments of the terminal web.
Embedded proteins
(connexons)
Gap junctions permit the
free diffusion of ions and
small molecules between
two cells.
Intermediate
filaments
Cell adhesion
molecules (CAMs)
Dense area
Proteoglycans
A spot desmosome ties
adjacent cells together.
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Epithelial Maintenance and Repair
o
Epithelia are replaced by division of germinative cells (stem cells)
o
Near basement membrane
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Singular = Epithelium; Plural = Epithelia
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Classes of Epithelia
1.
2.
Based on shape
•
Squamous epithelia — thin and flat
•
Cuboidal epithelia — square shaped
•
Columnar epithelia — tall, slender rectangles
Based on layers
•
Simple epithelium — single layer of cells
•
Stratified epithelium — several layers of cells
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Squamous Epithelia
o Simple squamous epithelium
• Absorption and diffusion
o Mesothelium
• Lines body cavities
o Endothelium
• Lines heart and blood vessels
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Simple Squamous Epithelium
LOCATIONS: Mesothelia lining ventral body cavities; endothelia lining heart
and blood vessels; portions of kidney tubules (thin sections of nephron loops);
inner lining of cornea; alveoli of lungs
FUNCTIONS: Reduces friction; controls vessel permeability; performs
absorption and secretion
Cytoplasm
Nucleus
Connective tissue
Lining of peritoneal cavity
LM  238
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Squamous Epithelia
o Stratified squamous epithelium
• Protects against attacks
• Keratin protein adds strength and water resistance
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Stratified Squamous Epithelium
LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum,
anus, and vagina
FUNCTIONS: Provides physical protection against abrasion, pathogens,
and chemical attack
Squamous
superficial cells
Stem cells
Basement
membrane
Connective
tissue
Surface of tongue
LM  310
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Cuboidal Epithelia
o Simple cuboidal epithelium
• Secretion and absorption
o Stratified cuboidal epithelia
• Sweat ducts and mammary ducts
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Simple Cuboidal Epithelium
LOCATIONS: Glands; ducts;
portions of kidney tubules; thyroid
gland
Connective
tissue
FUNCTIONS: Limited protection,
secretion, absorption
Nucleus
Cuboidal
cells
Basement
membrane
Kidney tubule
LM  650
Stratified Cuboidal Epithelium
LOCATIONS: Lining of some ducts
(rare)
FUNCTIONS: Protection, secretion,
absorption
Lumen
of duct
Stratified
cuboidal
cells
Basement
membrane
Nuclei
Connective
tissue
Sweat gland duct
LM  500
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Transitional Epithelium
o Tolerates repeated cycles of stretching and recoiling and returns to
its previous shape without damage
o Appearance changes as stretching occurs
o Situated in regions of the urinary system (e.g., urinary bladder)
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Transitional Epithelium
LOCATIONS: Urinary
bladder; renal pelvis;
ureters
FUNCTIONS: Permits
expansion and recoil
after stretching
Epithelium
(relaxed)
Basement membrane
Empty bladder
Connective tissue and
smooth muscle layers
LM  400
Epithelium
(stretched)
Full bladder
Urinary bladder
Basement membrane
Connective tissue and
smooth muscle layers
LM  400
LM  400
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Columnar Epithelia
o Simple columnar epithelium
• Absorption and secretion
o Pseudostratified columnar epithelium
• Cilia movement
o Stratified columnar epithelium
• Protection
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Simple Columnar Epithelium
LOCATIONS: Lining of
stomach, intestine, gallbladder,
uterine tubes, and collecting
ducts of kidneys
FUNCTIONS: Protection,
secretion, absorption
Microvilli
Cytoplasm
Nucleus
Intestinal lining
Basement
membrane
Loose
connective tissue
LM  350
Pseudostratified Ciliated Columnar Epithelium
LOCATIONS: Lining of
nasal cavity, trachea, and
bronchi; portions of male
reproductive tract
Cilia
Cytoplasm
FUNCTIONS: Protection,
secretion, move mucus
with cilia
Nuclei
Basement
membrane
Trachea
Loose
connective tissue
LM  350
Stratified Columnar Epithelium
LOCATIONS: Small areas of
the pharynx, epiglottis, anus,
mammary glands, salivary
gland ducts, and urethra
FUNCTION: Protection
Lumen
Loose
connective tissue
Deeper basal
cells
Superficial
columnar cells
Lumen
Cytoplasm
Nuclei
Salivary gland duct
Basement
membrane
LM  175
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Glandular Epithelia
o Endocrine glands
• Release hormones
• Into interstitial fluid
• No ducts
o Exocrine glands
• Produce secretions
• Onto epithelial surfaces
• Through ducts
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Glandular Epithelia
o
Modes of Secretion
1. Merocrine secretion
2. Apocrine secretion
3. Holocrine secretion
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o Merocrine Secretion
• Produced in Golgi apparatus
• Released by vesicles (exocytosis)
• For example, sweat glands
o Apocrine Secretion
• Produced in Golgi apparatus
• Released by shedding cytoplasm
• For example, mammary glands
o Holocrine Secretion
• Released by cells bursting, killing gland cells
• Gland cells replaced by stem cells
• For example, sebaceous glands
Secretory
vesicle
Golgi
apparatus
Nucleus
TEM  3039
Salivary gland
Mammary
gland
Breaks
down
Golgi apparatus
Secretion
Regrowth
Hair
Sebaceous
gland
Cells burst, releasing
cytoplasmic contents
Hair follicle
Cells produce secretion,
increasing in size
Cell division replaces
lost cells
Stem cell
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Glandular Epithelia
o Types of Secretions
• Serous glands
• Watery secretions
• Mucous glands
• Secrete mucins
• Mixed exocrine glands
• Both serous and mucous
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Glandular Epithelia
o Gland Structure
• Unicellular glands
• Mucous (goblet) cells are the only unicellular exocrine
glands
• Scattered among epithelia
• For example, in intestinal lining
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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)
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SIMPLE GLANDS
Duct
Gland
cells
SIMPLE
TUBULAR
Examples:
• Intestinal glands
SIMPLE COILED
TUBULAR
Examples:
• Merocrine sweat
glands
SIMPLE ALVEOLAR
(ACINAR)
Examples:
• Not found in adult; a
stage in development
of simple branched
glands
SIMPLE BRANCHED
TUBULAR
Examples:
• Gastric glands
• Mucous glands
of esophagus,
tongue, duodenum
SIMPLE BRANCHED
ALVEOLAR
Examples:
• Sebaceous (oil)
glands
COMPOUND GLANDS
COMPOUND
TUBULAR
Examples:
• Mucous glands (in mouth)
• Bulbo-urethral glands (in
male reproductive system)
• Testes (seminiferous
tubules)
COMPOUND ALVEOLAR
(ACINAR)
Examples:
• Mammary glands
COMPOUND
TUBULOALVEOLAR
Examples:
• Salivary glands
• Glands of respiratory
passages
• Pancreas
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Characteristics of Connective Tissue
1.
Specialized cells
2.
Solid extracellular protein fibers
3.
Fluid extracellular ground substance
The Extracellular Components of Connective Tissue (Fibers
and Ground Substance)
o
Make up the matrix
•
Majority of tissue volume
•
Determines specialized function
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Functions of Connective Tissue
o Establishing a structural framework for the body
o Transporting fluids and dissolved materials
o Protecting delicate organs
o Supporting, surrounding, and interconnecting other types of tissue
o Storing energy reserves, especially in the form of triglycerides
o Defending the body from invading microorganisms
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Classification of Connective Tissues
1.
Connective tissue proper
• Connect and protect
2.
Fluid connective tissues
• Transport
3.
Supporting connective tissues
• Structural strength
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Categories of Connective Tissue Proper
o Loose connective tissue
• More ground substance, fewer fibers
• For example, fat (adipose tissue)
o Dense connective tissue
• More fibers, less ground substance
• For example, tendons
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Connective Tissue Proper Cell Populations
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Fibroblasts
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Mast cells
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Fibrocytes
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Lymphocytes
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Adipocytes
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Microphages
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Mesenchymal cells
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Melanocytes
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Macrophages
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Fibroblasts
o The most abundant cell type
• Found in all connective tissue proper
• Secrete proteins and hyaluronan (cellular cement)
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Fibrocytes
o The second most abundant cell type
• Found in all connective tissue proper
• Maintain the fibers of connective tissue proper
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Adipocytes
o Fat cells
• Each cell stores a single, large fat droplet
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Mesenchymal Cells
o Stem cells that respond to injury or infection
• Differentiate into fibroblasts, macrophages, etc.
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Macrophages
o Large, amoeba-like cells of the immune system
• Eat pathogens and damaged cells
• Fixed macrophages stay in tissue
• Free macrophages migrate
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Mast Cells
o Stimulate inflammation after injury or infection
• Release histamine and heparin
o Basophils are leukocytes (white blood cells) that also contain
histamine and heparin
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Lymphocytes
o Specialized immune cells in lymphatic (lymphoid) system
• For example, lymphocytes may develop into plasma cells (plasmocytes)
that produce antibodies
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Microphages
o Phagocytic blood cells
• Respond to signals from macrophages and mast cells
• For example, neutrophils and eosinophils
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Melanocytes
o Synthesize and store the brown pigment melanin
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Connective Tissue Fibers
1.
Collagen fibers
2.
Reticular fibers
3.
Elastic fibers
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Collagen Fibers
o Most common fibers in connective tissue proper
o Long, straight, and unbranched
o Strong and flexible
o Resist force in one direction
o For example, tendons and ligaments
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Reticular Fibers
o Network of interwoven fibers (stroma)
o Strong and flexible
o Resist force in many directions
o Stabilize functional cells (parenchyma) and structures
o For example, sheaths around organs
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Elastic Fibers
o Contain elastin
o Branched and wavy
o Return to original length after stretching
o For example, elastic ligaments of vertebrae
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Ground Substance
o Is clear, colorless, and viscous
o Fills spaces between cells and slows pathogen movement
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Reticular
fibers
Melanocyte
Fixed
macrophage
Plasma cell
Mast cell
Elastic
fibers
Free
macrophage
Collagen
fibers
Blood
in vessel
Fibroblast
Adipocytes
(fat cells)
Mesenchymal
cell
Ground
substance
Lymphocyte
Elastic
fibers
Collagen
fibers
Fibroblast
Free
macrophage
Connective tissue proper
LM  502
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Embryonic Connective Tissues
o Are not found in adults
o Mesenchyme (embryonic stem cells)
• The first connective tissue in embryos
o Mucous connective tissue
• Loose embryonic connective tissue
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Mesenchymal
cells
Mesenchyme
LM  136
This is the first connective
tissue to appear in an embryo.
Mesenchymal
cells
Blood vessel
Mucous connective tissue
(Wharton’s jelly)
LM  136
This sample was taken from
the umbilical cord of a fetus.
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Loose Connective Tissues
o
The “packing materials” of the body
o
Three types in adults
1. Areolar
2. Adipose
3. Reticular
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Areolar Tissue
o Least specialized
o Open framework
o Viscous ground substance
o Elastic fibers
o Holds blood vessels and capillary beds
• For example, under skin (subcutaneous layer)
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Adipose Tissue
o
Contains many adipocytes (fat cells)
o
2 types of adipose tissue
1. White fat
2. Brown fat
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White fat
o Most common
o Stores fat
o Absorbs shocks
o Slows heat loss (insulation)
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Brown fat
o More vascularized
o Adipocytes have many mitochondria
o When stimulated by nervous system, fat breakdown accelerates,
releasing energy
o Absorbs energy from surrounding tissues
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Adipose Tissue
o Adipose cells
• Adipocytes in adults do not divide
• Expand to store fat
• Shrink as fats are released
• Mesenchymal cells divide and differentiate
• To produce more fat cells
• When more storage is needed
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Reticular Tissue
o Provides support
o Complex, three-dimensional network
o Supportive fibers (stroma)
• Support functional cells (parenchyma)
o Reticular organs
• Spleen, liver, lymph nodes, and bone marrow
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Adipose Tissue
LOCATIONS: Deep to the skin,
especially at sides, buttocks,
breasts; padding around eyes
and kidneys
FUNCTIONS: Provides
padding and cushions
shocks; insulates
(reduces heat loss);
stores energy
Adipocytes
(white adipose
cells)
Adipose tissue
LM  300
Reticular Tissue
LOCATIONS: Liver, kidney, spleen,
lymph nodes, and bone marrow
FUNCTIONS: Provides supporting
framework
Reticular
fibers
Reticular tissue
from liver
Reticular Tissue
LM  375
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Dense Connective Tissues
o Connective tissues proper, tightly packed with high numbers of
collagen or elastic fibers
• Dense regular connective tissue
• Dense irregular connective tissue
• Elastic tissue
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Dense Regular Connective Tissue
o Tightly packed, parallel collagen fibers
• Tendons attach muscles to bones
• Ligaments connect bone to bone and stabilize organs
• Aponeuroses attach in sheets to large, flat muscles
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Dense Regular Connective Tissue
LOCATIONS: Between skeletal
muscles and skeleton (tendons
and aponeuroses); between
bones or stabilizing positions
of internal organs (ligaments);
covering skeletal muscles;
deep fasciae
FUNCTIONS: Provides
firm attachment; conducts
pull of muscles; reduces
friction between muscles;
stabilizes relative positions
of bones
Collagen
fibers
Fibroblast
nuclei
Tendon
LM  440
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Dense Irregular Connective Tissue
o Interwoven networks of collagen fibers
• Layered in skin
• Around cartilages (perichondrium)
• Around bones (periosteum)
• Form capsules around some organs (e.g., liver, kidneys)
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Dense Irregular Connective Tissue
LOCATIONS: Capsules of
visceral organs; periostea
and perichondria; nerve
and muscle sheaths; dermis
FUNCTIONS: Provides
strength to resist forces
applied from many
directions; helps
prevent overexpansion
of organs such as
the urinary bladder
Collagen
fiber
bundles
Deep dermis
LM  111
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Elastic Tissue
o Made of elastic fibers
• For example, elastic ligaments of spinal vertebrae
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Elastic Tissue
LOCATIONS: Between vertebrae
of the spinal column (ligamentum
flavum and ligamentum nuchae);
ligaments supporting penis;
ligaments supporting transitional
epithelia; in blood vessel walls
Elastic
fibers
FUNCTIONS: Stabilizes
positions of vertebrae and
penis; cushions shocks;
permits expansion and
contraction of organs
Fibroblast
nuclei
Elastic ligament
LM  887
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Fluid Connective Tissues
o Blood and lymph
o Watery matrix of dissolved proteins
o Carry specific cell types (formed elements)
• Formed elements of blood
• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Platelets
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Fluid Elements of Connective Tissues
o Extracellular
• Plasma
• Interstitial fluid
• Lymph
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Red blood cells
Red blood cells, or
erythrocytes
(e-RITH-ro-sıts),
are
¯ ¯
responsible for the
transport of oxygen
(and, to a lesser degree,
of carbon dioxide) in
the blood.
Red blood cells
account for roughly
half the volume of
whole blood and
give blood its color.
White blood cells
White blood cells, or leukocytes
¯
¯
(LOO-ko-sıts;
leuko-, white), help defend
the body from infection and disease.
Neutrophil
Eosinophil
Monocytes
are phagocytes
similar to the
free macrophages in
other tissues.
Lymphocytes are uncommon in the blood
but they are the dominant cell type in lymph,
the second type of
fluid connective tissue.
Basophil
Eosinophils and neutrophils are phagocytes. Basophils promote inflammation much like mast cells in
other connective tissues.
Platelets
Platelets are
membrane-enclosed
packets of cytoplasm
that function in blood
clotting.
These cell fragments
are involved in the
clotting response
that seals leaks in
damaged or broken
blood vessels.
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Lymph
o Extracellular fluid
• Collected from interstitial space
• Monitored by immune system
• Transported by lymphatic (lymphoid) system
• Returned to venous system
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Fluid Tissue Transport Systems
o Cardiovascular system (blood)
• Arteries
• Capillaries
• Veins
o Lymphatic (lymphoid) system (lymph)
• Lymphatic vessels
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Support Soft Tissues and Body Weight
o Cartilage
• Gel-type ground substance
• For shock absorption and protection
o Bone
• Calcified (made rigid by calcium salts, minerals)
• For weight support
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Cartilage Matrix
o Proteoglycans derived from chondroitin sulfates
o Ground substance proteins
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Chondrocytes (cartilage cells) surrounded by lacunae
(chambers)
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Cartilage Structure
o No blood vessels
• Chondrocytes produce antiangiogenesis factor
o Perichondrium
• Outer, fibrous layer (for strength)
• Inner, cellular layer (for growth and maintenance)
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Matrix
New
matrix
Chondrocyte
Lacuna
Chondrocyte undergoes division
within a lacuna surrounded by
cartilage matrix.
Interstitial growth
As daughter cells secrete additional matrix, they
move apart, expanding the cartilage from within.
Dividing stem cell
Fibroblast
Perichondrium
New matrix
Chondroblasts
Immature
chondrocyte
Older matrix
Cells in the cellular layer
of the perichondrium
differentiate into
chondroblasts.
Appositional growth
These immature
chondroblasts secrete
new matrix.
Mature
chondrocyte
As the matrix enlarges, more
chondroblasts are incorporated;
they are replaced by divisions of
stem cells in the perichondrium.
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Types of Cartilage
1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage (fibrous cartilage)
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
Hyaline Cartilage
o Stiff, flexible support
o Reduces friction between bones
o Found in synovial joints, rib tips, sternum, and
trachea

Elastic Cartilage
o Supportive but bends easily
o Found in external ear and epiglottis
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Fibrocartilage (Fibrous Cartilage)
o Limits movement
o Prevents bone-to-bone contact
o Pads knee joints
o Found between pubic bones and intervertebral
discs
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Hyaline Cartilage
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;
reduces friction
between bony
surfaces
Chondrocytes
in lacunae
Matrix
LM  500
Hyaline cartilage
Elastic Cartilage
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
Chondrocyte
in lacuna
Elastic fibers
in matrix
LM  358
Elastic cartilage
Fibrocartilage
LOCATIONS: Pads within knee
joint; between pubic bones of
pelvis; intervertebral discs
FUNCTIONS:
Resists
compression;
prevents boneto-bone
contact; limits
movement
Chondrocytes
in lacunae
Fibrous
matrix
LM  400
Fibrocartilage

Bone or Osseous Tissue
o Strong (calcified calcium salt deposits)
o Resists shattering (flexible collagen fibers)
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Bone Cells or Osteocytes
o Arranged around central canals within matrix
o Small channels through matrix (canaliculi) access blood supply

Periosteum
o Covers bone surfaces
o Fibrous layer
o Cellular layer
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Canaliculi
Osteocytes
in lacunae
Matrix
Osteon
Central canal
Blood vessels
Osteon
LM  375
Fibrous
layer
Cellular
layer
Periosteum
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Membranes
o Physical barriers
o Line or cover portions of the body
o Consist of:
• An epithelium
• Supported by connective tissue
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Four Types of Membranes
1.
Mucous membranes
2.
Serous membranes
3.
Cutaneous membrane
4.
Synovial membranes
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Mucous Membranes (Mucosae)
o Line passageways that have external connections
o In digestive, respiratory, urinary, and reproductive tracts
o Epithelial surfaces must be moist
• To reduce friction
• To facilitate absorption and excretion
o Lamina propria
• Is areolar tissue
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Mucous secretion
Epithelium
Lamina propria
(areolar tissue)
Mucous membranes are coated with the
secretions of mucous glands. These
membranes line the digestive, respiratory,
urinary, and reproductive tracts.

Serous Membranes
o Line cavities not open to the outside
o Are thin but strong
o Have fluid transudate to reduce friction
o Have a parietal portion covering the cavity
o Have a visceral portion (serosa) covering the organs
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Three Serous Membranes
1.
Pleura
• Lines pleural cavities
• Covers lungs
2.
Peritoneum
• Lines peritoneal cavity
• Covers abdominal organs
3.
Pericardium
• Lines pericardial cavity
• Covers heart
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
Cutaneous Membrane
o Is skin, surface of the body
o Thick, waterproof, and dry

Synovial Membranes
o Line moving, articulating joint cavities
o Produce synovial fluid (lubricant)
o Protect the ends of bones
o Lack a true epithelium
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Epithelium
Areolar tissue
Dense irregular
connective tissue
The cutaneous membrane, or skin, covers the
outer surface of the body.
Articular (hyaline) tissue
Synovial fluid
Capsule
Capillary
Adipocytes
Areolar
tissue
Epithelium
Synovial
membrane
Bone
Synovial membranes line joint cavities and produce
the fluid within the joint.


Connective Tissues
1.
Provide strength and stability
2.
Maintain positions of internal organs
3.
Provide routes for blood vessels, lymphatic vessels, and nerves
Fasciae
o
Singular form = fascia
•
The body’s framework of connective tissue
•
Layers and wrappings that support or surround organs
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
Three Types of Fasciae
1.
Superficial fascia
2.
Deep fascia
3.
Subserous fascia
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Body wall
Connective Tissue Framework of Body
Body cavity
Superficial Fascia
• Between skin and
underlying organs
• Areolar tissue and
adipose tissue
• Also known as
subcutaneous layer
or hypodermis
Skin
Deep Fascia
• Forms a strong, fibrous
internal framework
• Dense connective tissue
• Bound to capsules,
tendons, and ligaments
Subserous Fascia
Rib
• Between serous
membranes and
deep fascia
• Areolar tissue
Serous membrane
Cutaneous membrane

Muscle Tissue
o
Specialized for contraction
o
Produces all body movement
o
Three types of muscle tissue
1. Skeletal muscle tissue
•
Large body muscles responsible for movement
2. Cardiac muscle tissue
•
Found only in the heart
3. Smooth muscle tissue
•
Found in walls of hollow, contracting organs (blood vessels;
urinary bladder; respiratory, digestive, and reproductive
tracts)
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
Classification of Muscle Cells
o Striated (muscle cells with a banded appearance)
o Nonstriated (not banded; smooth)
o Muscle cells can have a single nucleus
o Muscle cells can be multinucleate
o Muscle cells can be controlled voluntarily (consciously)
o Muscle cells can be controlled involuntarily (automatically)
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
Skeletal Muscle Cells
o Long and thin
o Usually called muscle fibers
o Do not divide
o New fibers are produced by stem cells (myosatellite cells)
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Skeletal Muscle Tissue
Cells are long, cylindrical,
striated, and multinucleate.
Nuclei
LOCATIONS: Combined
with connective tissues
and neural tissue in
skeletal muscles
FUNCTIONS: Moves or
stabilizes the position of
the skeleton; guards
entrances and exits to
the digestive,
respiratory, and urinary
tracts; generates heat;
protects internal organs
Muscle
fiber
Striations
Skeletal muscle
LM  180

Cardiac Muscle Cells
o Called cardiocytes
o Form branching networks connected at intercalated discs
o Regulated by pacemaker cells

Smooth Muscle Cells
o Small and tapered
o Can divide and regenerate
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Cardiac Muscle Tissue
Nucleus
Cells are short, branched,
and striated, usually with a
single nucleus; cells are
interconnected by
intercalated discs.
Cardiac
muscle
cells
LOCATION: Heart
FUNCTIONS:
Circulates blood;
maintains blood
(hydrostatic) pressure
Intercalated
discs
Striations
Cardiac muscle
LM  450
Smooth Muscle Tissue
Cells are short, spindle-shaped, and
nonstriated, with a single, central
nucleus.
LOCATIONS: Found in
the walls of blood vessels
and in digestive, respiratory,
urinary, and reproductive organs
Nucleus
FUNCTIONS: Moves food,
urine, and reproductive tract
secretions; controls
diameter of respiratory
passageways; regulates
diameter of blood vessels
Smooth
muscle
cell
Smooth muscle
LM  235

Neural Tissue
o Also called nervous or nerve tissue
• Specialized for conducting electrical impulses
• Rapidly senses internal or external environment
• Processes information and controls responses
o Neural tissue is concentrated in the central nervous system
• Brain
• Spinal cord
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
Two Types of Neural Cells
1.
Neurons
• Nerve cells
• Perform electrical communication
2.
Neuroglia
• Supporting cells
• Repair and supply nutrients to neurons
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
Cell Parts of a Neuron
o Cell body
• Contains the nucleus and nucleolus
o Dendrites
• Short branches extending from the cell body
• Receive incoming signals
o Axon (nerve fiber)
• Long, thin extension of the cell body
• Carries outgoing electrical signals to their destination
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NEURONS
NEUROGLIA (supporting cells)
Nuclei of neuroglia
Cell body
Axon
• Maintain physical structure
of tissues
• Repair tissue framework
after injury
• Perform phagocytosis
• Provide nutrients to neurons
• Regulate the composition of the
interstitial fluid surrounding neurons
Nucleolus
Nucleus
of neuron
Dendrites
LM  600
Dendrites
(contacted by
other neurons)
Mitochondrion
Nucleus
Axon (conducts
information to
other cells)
Microfibrils and
microtubules
Nucleolus
Contact with
other cells
Cell body (contains nucleus
and major organelles)
A representative neuron
(sizes and shapes vary widely)
Nuclei of neuroglia
Cell body
Axon
Nucleolus
Nucleus
of neuron
Dendrites
LM  600
NEUROGLIA (supporting cells)
• Maintain physical structure
of tissues
• Repair tissue framework
after injury
• Perform phagocytosis
• Provide nutrients to neurons
• Regulate the composition of the
interstitial fluid surrounding neurons
Dendrites
(contacted by
other neurons)
Mitochondrion
Nucleus
Axon (conducts
information to
other cells)
Microfibrils and
microtubules
Nucleolus
Cell body (contains nucleus
A representative neuron
and major organelles)
(sizes and shapes vary widely)
Contact with
other cells

Tissues Respond to Injuries
o
To maintain homeostasis
•
Cells restore homeostasis with two processes
1.
Inflammation
2.
Regeneration
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
Inflammation = Inflammatory Response
o The tissue’s first response to injury

Signs and symptoms of the inflammatory response include:
o Swelling
o Redness
o Heat
o Pain
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
Inflammatory Response
o Can be triggered by:
• Trauma (physical injury)
• Infection (the presence of harmful pathogens)
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
The Process of Inflammation
o Damaged cells release chemical signals into the surrounding
interstitial fluid
• Prostaglandins
• Proteins
• Potassium ions
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
The Process of Inflammation
o As cells break down:
• Lysosomes release enzymes that destroy the injured cell and attack
surrounding tissues
• Tissue destruction is called necrosis
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
The Process of Inflammation
o Necrotic tissues and cellular debris (pus) accumulate in the wound
• Abscess – pus trapped in an enclosed area
o Injury stimulates mast cells to release:
• Histamine
• Heparin
• Prostaglandins
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
The Process of Inflammation
o Dilation of blood vessels
• Increases blood circulation in the area
• Causes warmth and redness
• Brings more nutrients and oxygen to the area
• Removes wastes
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
The Process of Inflammation
o Plasma diffuses into the area
• Causes swelling and pain
o Phagocytic white blood cells
• Clean up the area
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
Regeneration
o When the injury or infection is cleaned up
• Healing (regeneration) begins

The Process of Regeneration
o Fibrocytes move into necrotic area
• Lay down collagen fibers
• To bind the area together (scar tissue)
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
The Process of Regeneration
o New cells migrate into area
• Or are produced by mesenchymal stem cells
o Not all tissues can regenerate
• Epithelia and connective tissues regenerate well
• Cardiac cells and neurons do not regenerate (or
regenerate poorly)
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Mast Cell Activation
stimulates
Exposure to Pathogens and Toxins
Injured tissue contains an
abnormal concentration of
pathogens, toxins, waste
products, and the chemicals
from injured cells.
When a tissue is
injured, a general
defense mechanism
is activated.
When an injury damages
connective tissue, mast
cells release a variety of
chemicals. This process,
called mast cell activation,
stimulates inflammation.
Mast cell
Mast Cell Activation
When an injury damages
connective tissue, mast
cells release a variety of
chemicals. This process,
called mast cell activation,
stimulates inflammation.
Mast cell
Histamine
Heparin
Prostaglandins
INFLAMMATION
Inflammation produces several familiar indications of
injury, including swelling, redness, warmth, and pain.
Inflammation may also result from the presence of
pathogens, such as harmful bacteria, within the tissues; the
presence of these pathogens constitutes an infection.
Increased Blood Flow
Increased Vessel Permeability
Pain
In response to the
released chemicals, blood
vessels dilate, increasing
blood flow through the
damaged tissue.
Vessel dilation is accompanied by
an increase in the permeability of
the capillary walls. Plasma now
diffuses into the injured tissue, so
the area becomes swollen.
The abnormal conditions
within the tissue and the
chemicals released by
mast cells stimulate nerve
endings that produce the
sensation of pain.
PAIN
Increased Local
Temperature
Increased Oxygen
and Nutrients
Increased
Phagocytosis
Removal of Toxins
and Wastes
The increased
blood flow and
permeability
causes the tissue
to become warm
and red.
Vessel dilation,
increased blood flow,
and increased vessel
permeability result in
enhanced delivery of
oxygen and nutrients.
Phagocytes in
the tissue are
activated, and
they begin
engulfing tissue
debris and
pathogens.
Enhanced circulation
carries away toxins and
waste products,
distributing them to the
kidneys for excretion, or
to the liver for
inactivation.
O2
Toxins
and wastes
Regeneration
Regeneration is the repair that
occurs after the damaged tissue has
been stabilized and the inflammation
has subsided. Fibroblasts move into
the area, laying down a collagenous
framework known as scar tissue.
Over time, scar tissue is usually
“remodeled” and gradually assumes
a more normal appearance.
Inflammation Subsides
Over a period of hours to days,
the cleanup process generally
succeeds in eliminating the
inflammatory stimuli.
Normal
tissue
conditions
restored
Inhibits mast
cell activation
Regeneration
Regeneration is the repair that
occurs after the damaged tissue has
been stabilized and the
inflammation has subsided.
Fibroblasts move into the area,
laying down a collagenous
framework known as scar tissue.
Over time, scar tissue is usually
“remodeled” and gradually assumes
a more normal appearance.

Aging and Tissue Structure
o Speed and efficiency of tissue repair decrease with age, due to:
• Slower rate of energy consumption (metabolism)
• Hormonal alterations
• Reduced physical activity
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
Effects of Aging
o Chemical and structural tissue changes
• Thinning epithelia and connective tissues
• Increased bruising and bone brittleness
• Joint pain and broken bones
• Cardiovascular disease
• Mental deterioration
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
Aging and Cancer Incidence
o Cancer rates increase with age
• 25% of all people in the United States develop cancer
• Cancer is the #2 cause of death in the United States
• Environmental chemicals and cigarette smoke cause cancer
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
Primary germ layers: ectoderm, mesoderm, and endoderm
o Three layers of cells formed early in embryonic development
o Specialize to form the four primary tissues

Nerve tissue arises from ectoderm
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


Muscle, connective tissue, endothelium, and mesothelium
arise from mesoderm
Most mucosae arise from endoderm
Epithelial tissues arise from all three germ layers
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Figure 4.14