Tissues Groups of cells with a common function Four primary
tissues: Epithelia Connective tissues Muscle Nervous
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Epithelial Tissues Line body cavities and cover surfaces
Glandular epithelia: epithelial cells adapted to make up glands:
Exocrine glands: secretion into ducts to exterior of body Endocrine
glands: secretion into the blood to carry chemical messages
throughout the body Functions of epithelium Protection Absorption,
secretion, and ion transport Filtration Forms slippery
surfaces
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2013 Pearson Education, Inc. Studying Human Tissue: Microscopy
Tissue is fixed Preserved Cut Sliced thin enough to transmit light
or electrons Stained Enhances contrast
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2013 Pearson Education, Inc. Characteristics of Epithelial
Tissue: Polarity Cells have polarity Apical surface (upper free)
exposed to exterior or cavity Basal surface (lower, attached) Both
surfaces differ in structure and function
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2013 Pearson Education, Inc. Apical Surface of Epithelial
Tissues May be smooth & slick Most have microvilli (e.g., brush
border of intestinal lining) Increase surface area Some have cilia
(e.g., lining of trachea)
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2013 Pearson Education, Inc. Basal Surface of Epithelial
Tissues Noncellular basal lamina Glycoprotein and collagen fibers
lies adjacent to basal surface Adhesive sheet Selective filter
Scaffolding for cell migration in wound repair
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Epithelial Tissues: Attachments Basement membrane: Structural
support Attaches epithelial layer to underlying tissues Junctions:
hold epithelial cells together: Tight junctions: nothing passes
Adhesion junctions/spot desmosomes: some movement between cells Gap
junctions: protein channels
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Lateral Surface Features Cell Junctions Tight junctions (zona
occludens) close off intercellular space Found at apical region of
most epithelial types Some proteins in plasma membrane of adjacent
cells are fused Prevent molecules from passing between cells of
epithelial tissue
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Tight Junction
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Lateral Surface Features Cell Junctions Adherens junctions
(zonula adherens) anchoring junction Transmembrane linker proteins
attach to actin microfilaments of the cytoskeleton and bind
adjacent cells Along with tight junctions, form the tight
junctional complex around apical lateral borders of epithelial
tissues
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Lateral Surface Features Cell Junctions Desmosomes two
disc-like plaques connected across intercellular space Plaques of
adjoining cells are joined by proteins called cadherins Proteins
interdigitate into extracellular space Intermediate filaments
insert into plaques from cytoplasmic side
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Desmosome
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Lateral Surface Features Cell Junctions Gap junctions
passageway between two adjacent cells Let small molecules move
directly between neighboring cells Cells are connected by hollow
cylinders of protein
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Gap Junction
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Epithelial Tissues
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Special Characteristics of Epithelia
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2013 Pearson Education, Inc. Classification of Epithelia All
epithelial tissues have two names One indicates number of cell
layers Simple epithelia = single layer of cells Stratified
epithelia = two or more layers of cells Shape can change in
different layers One indicates shape of cells Squamous Cuboidal
Columnar In stratified epithelia, epithelia classified by cell
shape in apical layer
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Epithelial Tissues: Classification Shape: Squamous: flattened
cells, line vessels, part of lungs, body surface Cuboidal: cube
shaped, form lining of tubules, glandular tissue Columnar: column
shaped; line respiratory, digestive, reproductive tracts
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Epithelial Tissues: Classification Number of layers:
Simple/single layered: adapted for diffusion across cell barriers;
line glands, and respiratory, digestive, reproductive systems
Stratified/multiple layered: protection, skin surface
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Naming Epithelia Naming the epithelia includes both the layers
(first) and the shape of the cells (second) i.e. stratified
cuboidal epithelium The name may also include any accessory
structures Goblet cells Cilia Keratin Special epithelial tissues
(don t follow naming convention) Pseudostratified Transitional
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Simple Squamous Epithelium Function Passage of materials by
passive diffusion and filtration Secretes lubricating substances in
serosae Location Renal corpuscles Alveoli of lungs Lining of heart,
blood and lymphatic vessels Lining of ventral body cavity
(serosae)
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Simple Squamous Epithelium Simple squamous lining the walls of
the capillary
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Simple Cuboidal Epithelium Description single layer of
cube-like cells with large, spherical central nuclei Function
secretion and absorption Location kidney tubules, secretory
portions of small glands, ovary & thyroid follicles
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Simple Cuboidal Epithelium
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Simple Columnar Epithelium Description Single layer of
column-shaped (rectangular) cells with oval nuclei Some bear cilia
at their apical surface May contain goblet cells Function
Absorption; secretion of mucus, enzymes, and other substances
Ciliated type propels mucus or reproductive cells by ciliary
action
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Simple Columnar Epithelium Location Non-ciliated form Lines
digestive tract, gallbladder, ducts of some glands Ciliated form
Lines small bronchi, uterine tubes, uterus
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Pseudostratified Columnar Epithelium Description All cells
originate at basement membrane Only tall cells reach the apical
surface May contain goblet cells and bear cilia Nuclei lie at
varying heights within cells Gives false impression of
stratification Function secretion of mucus; propulsion of mucus by
cilia
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Pseudostratified Columnar Epithelium Locations Non-ciliated
type Ducts of male reproductive tubes Ducts of large glands
Ciliated variety Lines trachea and most of upper respiratory
tract
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Stratified Epithelia Contain two or more layers of cells
Regenerate from below Major role is protection Are named according
to the shape of cells at apical layer
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Stratified Squamous Epithelium Description Many layers of cells
squamous in shape Deeper layers of cells appear cuboidal or
columnar Thickest epithelial tissue adapted for protection
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Stratified Squamous Epithelium Specific types Keratinized
contain the protective protein keratin Surface cells are dead and
full of keratin Non-keratinized forms moist lining of body openings
Function Protects underlying tissues in areas subject to abrasion
Location Keratinized forms epidermis Non-keratinized forms lining
of esophagus, mouth, and vagina
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Stratified Squamous Epithelium Non-keratinized vs.
Keratinized
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Stratified Cuboidal Epithelium Description generally two layers
of cube-shaped cells Function protection Location Forms largest
ducts of sweat glands Forms ducts of mammary glands and salivary
glands
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Stratified Columnar Epithelium Description several layers;
basal cells usually cuboidal; superficial cells elongated Function
protection and secretion Location Rare tissue type Found in male
urethra and vas deferens, largest ducts of salivary glands,
nasopharynx
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Transitional Epithelium Description Basal cells usually
cuboidal or columnar Superficial cells dome- shaped or squamous
Function stretches and permits distension of urinary bladder
Location Lines ureters, urinary bladder and part of urethra
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Glandular Epithelium Ducts carry products of exocrine glands to
epithelial surface Include the following diverse glands
Mucus-secreting glands Sweat and oil glands Salivary glands Liver
and pancreas Mammary glands May be: unicellular or
multicellular
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2013 Pearson Education, Inc. Exocrine Glands Secretions
released onto body surfaces (skin) or into body cavities More
numerous than endocrine glands Secrete products into ducts Examples
include mucous, sweat, oil, and salivary glands
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2013 Pearson Education, Inc. Unicellular Exocrine Glands The
only important unicellular glands are mucous cells and goblet cells
Found in epithelial linings of intestinal and respiratory tracts
All produce mucin Dissolves in water to form mucus Slimy
protective, lubricating coating Mucin + water mucus
Exocrine Vs. Endocrine Glands Endocrine Gland Characteristics:
Ductless glands Secrete substances directly into bloodstream
Produce molecules called hormones Which is Which?
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Connective Tissue Most diverse and abundant tissue Main classes
Connective tissue proper Blood Fluid connective tissue Cartilage
Bone tissue Components of connective tissue: Cells (varies
according to tissue) Matrix Protein fibers (varies according to
tissue) Ground substance (varies according to tissue) Common
embryonic origin mesenchyme Supporting connective tissues
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2013 Pearson Education, Inc. Major Functions of Connective
Tissue Binding and support Protecting Insulating Storing reserve
fuel Transporting substances (blood)
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2013 Pearson Education, Inc. Structural Elements of Connective
Tissue Three elements Ground substance Fibers Cells Composition and
arrangement varies in different connective tissues
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2013 Pearson Education, Inc. Ground Substance Unstructured
material that fills space between cells Medium through which
solutes diffuse between blood capillaries and cells Components
Interstitial fluid Cell adhesion proteins ("glue" for attachment)
Proteoglycans Protein core + large polysaccharides (chrondroitin
sulfate and hyaluronic acid) Trap water in varying amounts,
affecting viscosity of ground substance
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Ground Substance Interstitial (tissue) fluid within which are
one or more of the molecules listed below: Hyaluronic acid: a
polysaccharide. Very slippery; serves as a good lubricant for
joints. Common in most connective tissues. Proteoglycans: protein
and polysaccharide complex. Polysaccharides called
glyocosaminoglycans (chondroitin sulfate, keratin sulfate). Protein
part attaches to hyaluronic acid. Able to trap large amounts of
water. Adhesive molecules: hold proteoglycan aggregates together.
Chondronectin in cartilage, osteonectin in bone, fibronectin in
fibrous connective tissue. Functions as a molecular sieve through
which nutrients diffuse between blood capillaries and cells
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2013 Pearson Education, Inc. Connective Tissue Fibers Three
types of fibers provide support Collagen Strongest and most
abundant type Tough; provides high tensile strength Elastic fibers
Networks of long, thin, elastin fibers that allow for stretch and
recoil Reticular Short, fine, highly branched collagenous fibers
(different chemistry and form than collagen fibers) Branch, forming
networks that offer more "give"
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Extracellular Matrix - ECM ECM has 3 major components 1.
Protein fibers 2. Ground substance 3. Fluid Protein fibers Collagen
fibers. Composed of the protein collagen. Strong, flexible,
inelastic; great tensile strength (i.e. resist stretch). Perfect
for tendons, ligaments Elastic fibers. Contain molecules of protein
elastin that resemble coiled springs. Returns to its original shape
after stretching or compression. Perfect for lungs, large blood
vessels Reticular fibers. Formed from fine collagenous fibers; form
branching networks ( stroma). Fill spaces between tissues and
organs.
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2013 Pearson Education, Inc. Cells "Blasts" cells Immature
forum; mitotically active; secrete ground substance and fibers
Fibroblasts in connective tissue proper Chondroblasts in cartilage
Osteoblasts in bone Hematopoietic stem cells in bone marrow "Cyte"
cells Mature form; maintain matrix Chondrocytes in cartilage
Osteocytes in bone
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Connective Tissue Cells Fibroblasts - secrete the proteins
needed for fiber synthesis and components of the extracellular
matrix Adipose or fat cells ( adipocytes ) - Common in some tissues
(dermis of skin); rare in some (cartilage) Mast cells -Common
beneath membranes; along small blood vessels. Can release heparin,
histamine, and proteolytic enzymes in response to injury.
Leukocytes (WBCs) - Respond to injury or infection Macrophages -
Derived from monocytes (a WBC). Phagocytic; provide protection
Chondroblasts - form cartilage Osteoblasts - form bone
Hematopoietic stem cells - form blood cells Undifferentiated
mesenchyme (stem cells). Have potential to differentiate into adult
cell types.
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2013 Pearson Education, Inc. Other Cell Types in Connective
Tissues Fat cells Store nutrients White blood cells Neutrophils,
eosinophils, lymphocytes Tissue response to injury Mast cells
Initiate local inflammatory response against foreign microorganisms
they detect Macrophages Phagocytic cells that "eat" dead cells,
microorganisms; function in immune system
2013 Pearson Education, Inc. Areolar Connective Tissue Support
and bind other tissues Universal packing material between other
tissues Most widely distributed Provide reservoir of water and
salts Defend against infection Store nutrients as fat Fibroblasts
Loose arrangement of fibers Ground substance When inflamed soaks up
fluid edema
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Areolar Connective Tissue Description Gel-like matrix with: all
three fiber types (collagen, reticular, elastic) for support Ground
substance is made up by glycoproteins also made and secreted by the
fibroblasts. Cells fibroblasts, macrophages, mast cells, white
blood cells, adipocytes Highly vascular tissue
2013 Pearson Education, Inc. Adipose Tissue White fat Similar
to areolar but greater nutrient storage Cell is adipocyte Stores
nutrients Scanty matrix Richly vascularized Shock absorption,
insulation, energy storage Brown fat Use lipid fuels to heat
bloodstream not to produce ATP
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Adipose Tissue Description Closely packed adipocytes Have
nucleus pushed to one side by fat droplet Function Provides reserve
food fuel Insulates against heat loss Supports and protects organs
Location Under skin Around kidneys Behind eyeballs, within abdomen
and in breasts
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2013 Pearson Education, Inc. Reticular Connective Tissue
Resembles areolar but fibers are reticular fibers Fibroblasts
called reticular cells Supports free blood cells in lymph nodes,
the spleen, and bone marrow
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Reticular Connective Tissue Description network of reticular
fibers in loose ground substance Function form a soft, internal
skeleton (stroma) supports other cell types Location lymphoid
organs Lymph nodes, bone marrow, and spleen
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2013 Pearson Education, Inc. Dense Regular Connective Tissue
Closely packed bundles of collagen fibers running parallel to
direction of pull White structures with great resistance to pulling
Fibers slightly wavy so stretch a little Fibroblasts manufacture
fibers and ground substance Few cells Poorly vascularized
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Dense Regular Connective Tissue Description Primarily parallel
collagen fibers Fibroblasts and some elastic fibers Poorly
vascularized Function Attaches muscle to bone Attaches bone to bone
Withstands great stress in one direction Location Tendons and
ligaments Aponeuroses Fascia around muscles
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2013 Pearson Education, Inc. Dense Irregular Connective Tissue
Same elements but bundles of collagen thicker and irregularly
arranged Resists tension from many directions Dermis Fibrous joint
capsules Fibrous coverings of some organs
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Dense Irregular Connective Tissue Description Primarily
irregularly arranged collagen fibers Some elastic fibers and
fibroblasts Function Withstands tension Provides structural
strength Location Dermis of skin Submucosa of digestive tract
Fibrous capsules of joints and organs
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2013 Pearson Education, Inc. Elastic Connective Tissue Some
ligaments very elastic Those connecting adjacent vertebrae Many of
larger arteries have in walls
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2013 Pearson Education, Inc. Connective tissue proper: dense
connective tissue, elastic Description: Dense regular connective
tissue containing a high proportion of elastic fibers. Function:
Allows tissue to recoil after stretching; maintains pulsatile flow
of blood through arteries; aids passive recoil of lungs following
inspiration. Location: Walls of large arteries; within certain
ligaments associated with the vertebral column; within the walls of
the bronchial tubes. Photomicrograph: Elastic connective tissue in
the wall of the aorta (250x). Aorta Heart Elastic fibers Figure
4.8f Connective tissues.
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Cartilage Characteristics: Firm, flexible tissue Contains no
blood vessels or nerves Matrix contains up to 80% water Cell type
chondroblasts and chondrocytes Types: Hyaline Elastic
Fibrocartilage
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2013 Pearson Education, Inc. Cartilage Lacks nerve fibers Up to
80% water - can rebound after compression Avascular Receives
nutrients from membrane surrounding it Perichondrium
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Hyaline Cartilage Description Imperceptible collagen fibers
(hyaline = glassy) Chodroblasts produce matrix Chondrocytes lie in
lacunae Function Supports and reinforces Resilient cushion Resists
repetitive stress Location Ends of long bones Costal cartilage of
ribs Cartilages of nose, trachea, and larynx Location
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Elastic Cartilage Description Similar to hyaline cartilage More
elastic fibers in matrix Function Maintains shape of structure
Allows great flexibility Location Supports external ear
Epiglottis
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Fibrocartilage Description Matrix similar, but less firm than
hyaline cartilage Thick collagen fibers predominate Function
Tensile strength and ability to absorb compressive shock Location
Intervertebral discs Pubic symphysis Discs of knee joint
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Connective Tissue Supports and Connects Body Parts: Basement
Membrane Fibrous connective tissue: Loose: surrounds many organs,
lines cavities around blood vessels Dense: tendons, ligaments,
deeper layers of skin Elastic: surrounds stomach and bladder,
maintains shape Reticular: internal framework of soft organs
(liver) and lymphatic system
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2013 Pearson Education, Inc. Bone Also called osseous tissue
Supports and protects body structures Stores fat and synthesizes
blood cells in cavities More collagen than cartilage Has inorganic
calcium salts Osteoblasts produce matrix Osteocytes maintain the
matrix Osteons structural units Richly vascularized
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Bone Tissue Function Supports and protects organs Provides
levers and attachment site for muscles Stores calcium and other
minerals Stores fat Marrow is site for blood cell formation
Location Bones
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Blood Tissue Description red and white blood cells in a fluid
matrix Function transport of respiratory gases, nutrients, and
wastes Location within blood vessels Characteristics An atypical
connective tissue Consists of cells surrounded by fluid matrix
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2013 Pearson Education, Inc. Blood Also contains white blood
cells and platelets Fibers are soluble proteins that precipitate
during blood clotting
2013 Pearson Education, Inc. Muscle Tissue Highly vascularized
Responsible for most types of movement Three types Skeletal muscle
tissue Found in skeletal muscle Voluntary Cardiac muscle tissue
Found in walls of heart Involuntary Smooth muscle tissue Mainly in
walls of hollow organs other than heart Involuntary
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Muscle Tissue: Contracts for Movement Skeletal muscle: Moves
body parts Voluntary, multinucleated Cardiac muscle: Function in
the heart Involuntary, single nucleus Smooth muscle: Surrounds
hollow structures Involuntary, single nucleus
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Skeletal Muscle Tissue Characteristics Long, cylindrical cells
Multinucleate Obvious striations Function Voluntary movement
Manipulation of environment Facial expression Location Skeletal
muscles attached to bones (occasionally to skin)
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Cardiac Muscle Tissue Function Contracts to propel blood into
circulatory system Characteristics Branching cells Uni-nucleate
Intercalated discs Location Occurs in walls of heart
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Smooth Muscle Tissue Characteristics Spindle-shaped cells with
central nuclei Arranged closely to form sheets No striations
Function Propels substances along internal passageways Involuntary
control Location Mostly walls of hollow organs
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Nervous Tissue
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2013 Pearson Education, Inc. Nervous Tissue Main component of
nervous system Brain, spinal cord, nerves Regulates and controls
body functions Neurons Specialized nerve cells that generate and
conduct nerve impulses Neuroglia Supporting cells that support,
insulate, and protect neurons
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Nervous Tissue: Transmit Impulses Neuron: specialized nervous
system cell: Structural components: cell body, dendrites, axon
Glial cells: support cells to neurons
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Nervous Tissue Function Transmit electrical signals from
sensory receptors to effectors Location Brain, spinal cord, and
nerves Description Main components are brain, spinal cord, and
nerves Contains two types of cells Neurons excitatory cells
Neuroglial - supporting cells