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THE TISSUES
Tissues Groups of cells that are similar in structure and perform a common or related
function

The Four Primary Tissue Types

Epitehelial tissue

o Functions of epithelial tissue

Protection
Absorption
Filtration
Excretion
Secretion
Sensory reception
o Special characteristics of epithelium
Cellularity composed mainly of closely-packed cells
Specialized contacts cells are joined by tight junctions and
desmosomes
Polarity
Apical surface free surface exposed to the body exterior or
cavity
Basal surface attached surface
Supported by connective tissue (basement membrane)
Avascular but innervated no blood vessels but there are nerve fibers
Regeneration lost cells are rapidly replaced by cell division
o Classification of epithelial tissue
Number of cell layers present
Simple one layer of cells
Stratified more than one layer of cells
The shape of the cell
Squamous scalelike
Cuboidal cube-shaped
Columnar column-shaped
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o Types of epithelial tissue

Simple epithelia
Simple squamous
o Function Permits diffusion and filtration; secretes
lubricating substances in serous membranes
o Location Kidney glomeruli; air sacs of lungs; lines the
heart, blood vessels, and lymphatic vessels; lines the
serous membranes
Simple cuboidal
o Function secretion and absorption
o Location Kidney tubules; ducts and secretory portion
of small glands; ovary surface
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Simple columnar
o Function Absorption; secretion of mucus (via the
Goblet cells), enzymes, and other substances; ciliated
type propels materials by ciliary action
o Location Nonciliated type: lining of the digestive tract,
gallbladder, and excretory ducts; Ciliated type: lines
small bronchi, uterine tubes, and portions of the uterus
Pseudostratified
o Single layer of cells of differing heights
o Function Secretion, esp. mucus
o Location Ciliated type lines the trachea and most of
the upper respiratory tract; Nonciliated type found in
sperm-carrying ducts and the ducts of large glands
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Stratified epithelia

Stratified squamous
o Function Protects delicate tissues in areas subject to
abrasion
o Location Nonkeratinized type found in the esophagus,
mouth and vagina; Keratinized type found in the
epidermis of the skin
Stratified cuboidal
o Rare Found in ducts of large glands
Stratified columnar
o Rare Found in the pharynx, male urethra, and at
points of transition
Transitional
o Function stretches and permits the distension of the
urinary organs
o Location Lines the ureters, bladder, and part of the
urethra
Glandular epithelia
Endocrine glands do not have ducts; secrete their chemicals
(hormones) directly into the blood or interstitial fluid
Exocrine glands have ducts; secrete their products onto body
surfaces or into body cavities
Connective tissue
o Functions of connective tissue
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Binding and support (Ex. Bone)

Protection (Ex. Cartilage)
Insulation (Ex. Adipose tissue)
Transportation (Ex. Blood)
o Classification of connective tissue
Common origin all connective tissues arise from mesenchyme
Degrees vascularity all connective tissues have a blood supply,
except cartilage
Extracellular matrix connective tissues are composed mainly of a
non-living extracellular matrix secreted by the living tissues
interspersed within it
o Structural elements of connective tissue
Ground substance fills the space between the connective tissue cells
and contains the fibers
Fibers
Collagen fibers constructed mainly of fibrous collagen
proteins
o Extremely tough and resist longitudinal stress (high
tensile strength)
Elastic fibers long thin fibers that contain elastin proteins
o Elastin fibers stretch and recoil, providing elasticity
Reticular fibers
o Fine collagenous fibers that branch extensively; provide
support
Cell types synthesize and maintain the health of the matrix
Fibroblasts - found in connective tissue proper
Chondroblasts found in cartilage
Osteoblasts found in bone
Hematopoietic stem cells found in blood
o Types of connective tissue
Connective tissue proper
Areolar connective tissue
o Functions of areolar connective tissue
Supporting and binding other tissues
Holding body fluids
Defending against infection
Storing nutrients as fat (in fat cells)
o Location
Underlying epithelia; surrounds capillaries;
encases organs
Adipose tissue
o Highly vascularized; very little matrix
o Functions of adipose tissue
Fuel storage
Insulation
Support and protection of organs
o Location under skin; around kidneys; within
abdomen; in breasts
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Reticular tissue

o Functions of reticular tissue

Forms a soft internal skeleton that supports
other cell types
o Location lymphoid organs (lymph nodes, bone
marrow, spleen)
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Dense regular connective tissue

o Contains closely packed collagen fibers arranged in the
same direction
o Functions of dense regular connective tissue
Attaches muscles to bones or to other muscles;
withstands great tensile stress in one direction
o Location tendons, most ligaments, aponeuroses
Dense irregular connective tissue
o Contains bundles of collagen fibers arranged in many
different directions
o Functions of dense irregular connective tissue
Able to withstand tension in many directions;
provides structural strength
o Location dermis of the skin; submucosa of the
digestive tract; fibrous capsules or organs and of joints
Cartilage
Lacks nerve fibers and is avascular

Types of cartilage
o Hyaline cartilage most abundant cartilage
Contains large numbers of collagen fibers but
they are not apparent and the matrix is glassy
Functions of hyaline cartilage
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Supports and reinforces; provides

cushioning; resists compressive stress
Location the embryonic skeleton; covers the
ends of long bone; costal cartilages and ribs;
nose; trachea; pharynx
o Elastic cartilage
Matrix contains large amounts of elastic fibers
Functions of elastic cartilage
Maintains the shape of a structure, while
allowing great flexibility
Location external ear; epiglottis
o Fibrocartilage
Matrix contains large amounts of thick collagen
fibers
Functions of fibrocartilage
Provides tensile strength with the ability
to absorb compressive shock
Location intervertebral discs; pubic
symphysis; discs of knee joint

Bone
Calcified extracellular matrix
Functions of bone
o Support and protection; leverage for muscles; stores
calcium, minerals, and fat; site of blood cell formation
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Location skeletal bones

Blood
Fluid extracellular matrix; soluble proteins are apparent
during blood clotting
Functions of blood
o Transport of respiratory gases, nutrients, wastes and
other substances; Protection against infection and
disease
Location contained within blood vessels
Muscle
o Functions of muscle Body movement
o Special characteristics of muscle Contain actin and myosin proteins that
produce movement or contraction
o Classification of muscle based on the presence of striations and control of
movement
o Types of muscle
Skeletal muscle
Striated, voluntary, multinucleated cells, arranged in long,
cylindrical cells
Function: Voluntary movement; locomotion; manipulation of
the environment; facial expression; voluntary control
Location In skeletal muscles attached to bones or sometimes
skin
Cardiac muscle
Striated, involuntary, uninucleate (usually), interconnected
cells, arranged in branches; connected by specialized junctions
called intercalated discs
Location The walls of the heart
Smooth muscle
Nonstriated, involuntary, uninucleated, spindle-shaped cells
Location Mostly in the walls of hollow organs
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Nervous tissue
o Functions of nervous tissue Transmission of electrical signals
o Location Brain, spinal cord, and nerves
o Cell populations present in nervous tissue
Glial cells nonconducting cells that support, insulate, and protect
neurons
Neurons conducting cells that transmit electrical impulses

Steps of Tissue Repair

Inflammation injury to a tissue triggers the inflammatory response. Pain,

swelling, redness, and heat are observed at the site. White blood cells and protective
chemicals are delivered to the site to begin the healing process.
Granulation Granulation tissue begins to form at the site of injury. These tissues
and the accompanying capillaries form scaffolding on which cells can use to
reconstruct the site.
Regeneration and fibrosis - Epithelia cells begin to regenerate and scar tissue is
formed