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TISSUES
- Group of cells with a common embryonic origin and with
similar structure and function
- The arrangement of tissues determine each organs structure
and function
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Epithelium (covering)
2
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Nervous (control)
4
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Tight junction
2
...
Gap junction
TIGHT JUNCTIONS
- Form fluid - tight seals between cells like the seal on a
sandwich bag
- Common among epithelial cells that line the stomach,
intestines, urinary bladder
- Prevents fluid in a cavity from leaking into the body by
passing between cells
ANCHORING JUNCTIONS
- Fasten cells to one another or to the extracellular fluid
material
- Common in tissues subjected to friction and stretching
e
...
outer layer of skin, cardiac muscle, epithelial lining of GIT
Desmosome
- most common type
- forms firm attachments between cells like spot welds
- on the cytoplasmic surface, intermediate filaments of the
cytoskeleton attach to a dense plaque of proteins

GAP JUNCTIONS
- Permit electrical or chemical signals to pass from one cell to
cell
- Allow the rapid spread of action potentials from one cell to
the next in some parts of the nervous system and in muscle of
the heart and GIT
- Chemical and electrical signals that regulate growth and
differentiation may travel by way of gap junctions in a
developing embryo
Connexons
- Proteins spanning the gap forming minute fluid-filled
tunnels
- A tunnel where ions and small molecules ( glucose and
amino acids ) can pass directly from the cytosol of one cell
into the cytosol of the next
- Cancer cells do not have gap junctions and therefore cannot
communicate with each other, resulting to uncoordinated cell
division and occurs in an uncontrolled manner
EPITHELEAL TISSUE
- Epithelium
- The lining, covering, and the glandular tissue of the body
- Glandular epithelium forms various glands in the body
- The cells of the most epithelial tissues are constantly
replaced by mitosis of progenitor cells, thus, epithelial tissue
is constantly being regenerated
- Covering and lining epithelium covers all free body surfaces
and contains versatile cells
...
Protection
- The epithelium of the skin protects against bacterial and
chemical damage
- The epithelial lining of the respiratory tract has cilia, which
sweep dust and other debris away from the lungs
2
...

3
...
Secretion
- Specialty of the gland, which produce such substances as
perspiration, oil, digestive enzymes, and mucus

SPECIAL CHARACTERISTICS
1
...
Presence of apical surface
Apical Surfaces
- one free surface or edge present in all membranes
- exposed to the body’ exterior or to the cavity of an internal
organ
- the exposed surfaces of some epithelia are slick and smooth,
but others exhibit cell surface modifications such as microvilli
or cilia
3
...
Avascular – Epithelial tissue that has no blood supply of
their own and depend on diffusion from the capillaries in the
underlying connective tissue for food and oxygen
5
...
Simple Epithelia
2
...
Simple Squamous
- Flattened like fish scales (squam = scale)
- Single layer of thin squamous cells resting on a basement
membrane
- The cells fit closely together
- Usually form membranes where filtration or exchange of
substances by rapid diffusion occurs
- Forms the serous membranes or serosae
( slick membranes that line the ventral body cavity and cover
the organs in that cavity )
2
...
Simple Columnar
Made up of a single layer of tall cells that firm closely
together
Goblet cells – producing a lubricating mucus
Lines the entire length of the digestive tract from the stomach
to the anus
Mucosae / mucosa / mucus membrane - epithelial tissues
that line body cavities open to the body exterior
4
...
STRATIFIED EPITHELIA
- Consist of two or more layers
- More durable than the simple epithelia
- Primary function is protection
Types of Stratified Epithelia
1
...
Stratified Cuboidal and Stratified Columnar
Stratified cuboidal – consists of two cell layers with cuboidal
surface cell
Stratified columnar – columnar cells, but its basal cell vary in
size and shape
- Both of these epithelia are rare in the body, found mainly in
the ducts of large glands
3
...
Glandular Epithelium
Gland – consists of one or more cells that make and secret
particular product
Secretion
- the product produced by the gland
- typically contains protein molecules in an aqueous (water
based fluid)
- an active process in which the glandular cells obtain needed
materials from the blood and use them to make their
secretion, which then discharge
TWO MAJOR TYPES OF GLAND
1
...
Exocrine
- With ducts, where their secretions empty through the ducts
to the epithelial surface
- Both internal and external
- Sweat and oil glands
(External) liver
(Internal) pancreas
CONNECTIVE TISSUE
- Connects body parts
- Found everywhere in the body
- The most abundant and widely distributed of the tissue
types
Functions:
1
...
Support
3
...
Variation in blood supply
- Well vascularized (good blood supply)
- Tendons and ligaments have poor blood supply and
cartilages are avascular
- Tendons, ligaments and cartilages heal very slowly when
injured (due to poor blood supply)
2
...
Collagen (white) fibers
2
...
Reticular (fine collagen) fibers
The fibers are made by CT cells and then secreted
Types of Connective Tissues
The major differences of CT are their fiber type and the
number of fibers in the matrix
1
...
Cartilage
3
...
Loose CT
5
...
Adipose CT
7
...
Blood
Bone
- Osseous tissue
- Composed of bone cells sitting in cavities called lacunae and
surrounded by layers of a very hard matrix that contains
calcium salts in addition to larger number of collagen fibers
- Has an exceptional ability to protect and support other body
organs because of its rock-like hardness
e
...
the skull protects the brain
Cartilage
- Less hard and more flexible than bone
- Found only in few places in the body
Types:
1
...
Supporting structures of the larynx
2
...
Articular surface of the bone
4
...
Fibrocartilage
- Form the cushion-like discs between the vertebrae of the
spinal column
3
...
g
...
Tendons – attach skeletal muscles to bones
2
...
Dermis of the skin – arranged in sheets
Loose CT
- Softer and have more cells and fewer fibers than any other
CT type except blood
Areolar CT
- Anchors internal organs
- Soft pliable tissues
- Its fluid matrix contains all types of fibers forming a loose
network
- Most of the matrix appears to be an empty space, explaining
the name of the tissue
(areola = small open space)
Functions:
1
...
Provides nutrients to all body cells
3
...
Anchors internal organs
5
...
Form the subcutaneous tissue beneath the skin, where it
insulates the body and protects it from extreme cold or heat
2
...

3
...
it forms the stroma (bed or matress)
2
...
Skeletal
2
...
Smooth

SKELETAL MUSCLE
- Packaged by CT sheets into organs
- Can be controlled voluntarily, forming the flash of the body
- Pulls the bones and skin when it contracts
- Contraction causes gross body movements or changes in
facial expressions
- The cells of skeletal muscles are long, cylindrical and
multinucleated with obvious striations (stripes)
CARDIAC MUSCLE
- Found only in the heart
- The heart acts as pump and propels blood through the blood
vessels because of its contraction
- Cardiac cells are straited, uninucleated, branched cells that
fit tightly together ( like clasped fingers ) at junctions called
intercalated disk
- Intercalated disk contain gap junctions that allow ions to
pass freely from cell to cell, resulting in rapid conduction of
the exciting electrical impulse across the heart
- Involuntary muscle , which means that we cannot
continuously control the activity of the heart
SMOOTH MUSCLE
- Visceral organs (absence of striations)
- Smooth muscle cells have a single nucleus and are spindleshaped
(pointed at each end)
- Found in the walls of hollow organs such as stomach,
bladder, uterus, blood vessels
- Smooth muscle contraction causes alternating constriction
( becomes smaller ) and dilation ( enlarges ) of the cavity of an
organ to propel substances through the organ along a specific
pathway
Peristalsis – wave-like motion that keeps food moving through
the small intestine
NERVOUS TISSUE
Neurons – receive and conduct electrochemical impulses
from one part of the body to another
Major functional characteristics:
1
...
Conductivity
- The cytoplasm is drawn out into long extensions ( as much
as 3 feet or more in the leg, which allows a single neuron to
conduct an impulse over long distances in the body )
- Neurons along with a special group of supporting cells ( that
insulate, support, and protect the delicate neurons ) make up
the structures of the nervous system ( brain, spinal cord, and
nerves )

Tissue Repair/Wound Healing
- Begins almost immediately when tissue injury occurs,
stimulating the body’s inflammatory and immune responses
Inflammatory response – generalized non-specific body
response that attempts to prevent further injury
Immune response – extremely specific and mounts a vigorous
attack against recognize invaders (bacteria, viruses or toxins)
Factors Affecting Wound Healing
1
...
Severity of the injury
Clean cuts (incisions) heal much more successfully than
ragged tears (lacerations) of the tissue
Types of Wound Healing
1
...
Fibrosis
Regeneration – replacement of destroyed tissue by the same
kind of cells
Fibrosis – involves repair by dense (fibrous) connective tissue,
forming scar tissue
Types of Skin Wound Healing
1
...
Deep wound healing
Epidermal wound healing
- Occurs within 24-48 hours after injury
- Skin injury ( abrasion ) – response to injury – basal epidermal
cells in the area of the wound break their contacts with the
basement membrane – enlargement of the basal epidermal
cells – migration of basal epidermal cells as a sheet across the
wound until all advancing cells from opposite sides of the
wound meet – inhibition of continued migration / fusion of
basal epidermal cells
(Contact Inhibition) – epidermal growth factor stimulates
other epidermal cells to divide and replace the ones that have
left – resurface of the wound – division of the migrated cells
to form new strata – thickening of the epidermis
Contact Inhibition
- Inhibition / cessation of the continued migration / fusion of
basal epidermal cells
- An epidermal cell changes its direction of movement when it
encounters another epidermal cell, until it encounters
another cell and so on
- Continued migration of the epidermal cells stops when it is
finally in contact on all sides with other epidermal cells

Rule : Contact inhibition occurs only among like cells ( it does
not occur between epidermal cells and other types of cells )
- Malignant cells do not obey the rules of contact inhibition
- Malignant cells have the ability to invade body tissues with
few restrictions
Deep wound healing
Phases:
1
...
Migratory
3
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Maturation
Inflammatory Phase
- Vascular and cellular response that serves to dispose
microbes, foreign material and dying tissue in preparation for
repair – vasodilation and ↑ permeaability of blood vessels –
migration of WBC (neutrophils and monocytes /
macrophages) and mesenchymal cells from the bloodstream
into the wound – phagocytosis of microbes, dead tissues
/cells and other harmful substances – clot formation – clot
hold the edges of the wound together – walls off the
wounded area
- Prevention of bacteria and other harmful substances from
spreading to surrounding tissues – exposure of clot to the air
(hemostasis) – drying and hardening of the clot – scab
formation
Migratory Phase
- Migration of epithelial cells beneath the scab to bridge the
wound – migration of fibroblasts along fibrin threads –
fibroblasts synthesizes collagen fibers and glycoproteins – scar
tissue formation (fibrosis) – regrowth of the damaged blood
vessels – granulation tissue formation composed of capillaries
- Granulation tissue – delicate pink tissue filling the wound
- The capillaries are fragile and bleed freely , as when a scab is
picked away from a skin wound
Proliferative Phase
- Extensive growth of epithelial cells benaeth the scab –
deposition of collagen by the fibroblasts in random patterns –
continuing growth of blood vessels
Maturation Phase
- Restoration of dermis to normal thickness – scab sloughs off
– collagen fibers become more organized - ↓ number of
fibroblasts – restoration of blood vessels to normal

FIBROSIS
- The process of scar tissue formation
- Sometimes so much scar tissue is formed that that a raised
scar results, one that is elevated above the normal epidermal
surface
Types of Pathologic scar:
1
...
Keloid scar
Hypertrophic Scar
- The scar remain within the boundaries of the original wound
Keloid Scar
- Scar extends beyond the boundaries of the original wound
into normal surrounding tissues
DEVELOPMENTAL ASPECTS OF SCAR AND TISSUE
- It begins as a single cell, which divides thousand to
form multicellular embryonic body
- The cells begin to specialize to form the primary tissue
during the very early embryonic development and by birth,
most organs are well formed and functioning
CELL DIVISION AND GROWTH PERIOD
- Cell division is very important during the body’s growth
period
- Most cells (except neuron) undergo mitosis until the end of
puberty and maturity
- Cells that continually divides (even after maturity)
1
...
Liver cells (when damaged)
- Cells that completely lose their ability to divide ( amitotic )
1
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Nervous tissue
Amitotic tissues are severely handicapped because the lost
cells cannot be replaced by the same type of cells
AGING PROCESS
- Begins once maturity has been reached
- The cause of aging is still unknown
Theories :
1
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Radiation
3
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Epithelial tissues
2
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Muscle tissue
4
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Epithelial membranes become thinner and are more easily
damaged
- Which causes sagging and loss of elasticity of the skin
2
...
Some endocrine glands produce decreasing amounts of
hormones and the body processes that they control ( such as
metabolism and reproduction ) become less efficient or stop
altogether
Connective Tissues
1
...
Bones become porous and weak
3
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Atrophy
- Major factor is the decreased efficiency of the circulatory
system, reducing nutrient and oxygen delivery to the body
tissues
CELL AND TISSUE MODIFICATION
1
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Hyperplasia
3
...
g
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anemia – the bone marrow goes hyperplasia so that
RBC may be produced at a faster rate
b
...
g

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