Tissues
Chapter 5
Four Major types:
 Epithelial:
form protective coverings, fxn in
secretion and absorption
 Connective: supports soft body parts and
bind structures together
 Muscle: produces body movements
 Nervous: conducts impulses that help
control and coordinate body activities.
Epithelial Tissues
• Found throughout the body, covers
organs, lines body cavities and lines
hollow organs.
• It always has a free (apical) surface
(not covered)
• Underside is attached to connective
tissue by a thin, nonliving layer
called the basement membrane.
• Usually is lacking in blood vessels,
receiving nutrients by diffusion from
connective tissue
Epithelieal Continued
Readily divide, resulting in fast healing
injuries
 Tightly packed: making good protective
barriers to the outside
 Some invloved in absorption, excretion,
and excretion.
 Classified according to shape, number of
layers of cells
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Classification Of Epithelial Cells
Squamous: thin, flattened cells
Cuboidal: cube shaped
Columnar: tall, elongated
Single layers: simple
Stratified: two or more layers
The free surface epithelial cells are
modified in ways that reflect their
specialized functions.
Simple Squamous Epitheleal Con.
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Line air sacs (alveoli) of lungs.
Forms walls of capillaries
Lines the insides of blood and lymph
vessels
Covers the membranes that line body
cavities
Because they are so thin, they are easily
damaged.
Simple Cuboidal Epithelial Cells
Single Layer
Cube shaped
Covers ovaries and most of the
kidney tubules and the ducts of
certain glands
Functions in secretion and absorption
in glands of the kidneys and secrets
glandular products.
Simple Cuboidal Eptherlium
Simple Columnar
Epithelium
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Elongated: longer than they are wide
Single layer of cells, with elongated nuclei.
May be ciliated
Ciliated cells in the female reproductive tubes
cilia aid in movement of the egg
 Nonciliated SCE cells line the uterus and most
organs of the digestive tract including the
stomach and both intestines/
SCE
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The elongation leads to the formation of
thick tissue which provides protection for
underlying tissues
Some secrete digestive fluids and absorb
nutrients from digested foods
Those specialized for absorption often
have many tiny extensions from their
surfaces called microvilli to increase
surface area for greater absorption
SCE
► Specialized
flask shaped glandular cells
(goblet cells) are often scattered among
them. They secrete a protective fluid
(mucus) onto the free surface of the tissue
Simple Columnar Epithethelium
Cells
Pseudostratified Columnar
Epithelium
Appear to be stratified/layered but are
not.
 This is due to nuclei of the cells are found
in two or more layers. All of the cells share
the same basement membrane. Some of
them may not contact the free surface.
 Commonly have cilia.
 Goblet cells in this tissue secrete mucus.
 Found in passages of respiratory system.
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Pseudostratified Columnar
Stratified Squamous Epi
Relatively thick
Cell division occurs in deeper layers and newer cells
push older ones to the surface where they flatten. In
naming stratified epi tissues, based on cell shape, the
appearance of the top layer is used.
 Forms the outer layer of the skin. As skin cells age,
they accumulate a protein called keratin, then harden
and die. Keritinization pr4oduces a covering of dry,
tough protective material preventing water and other
substances from escaping and blocking various
chemicals and microorganisms from entereing.
 Stratifired Squ. Epi lines the oral cavity, esophagus,
vagina and anal canal. Here it is not keratinized, stays
soft and moist and surface cells remain alive.
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Stratified Squamous epi
Stratified Cuboidal Epi
Two or 3 layers of cuboidal cells forming a
lining of a lumen. Provides more
protection than a single layer of cells.
 Lines larger ducts of the mammary glands,
sweat glands, salivary glands, and
pancreas. Also forms the lining of
developing ovarian follicles and
seminiferous tubules.
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Stratified cuboidal Epi
Stratified Columnar Epi
Several layers of cells
 Superficial cells are columnar, base layers
are cuboidal. So, look for layers of cells
and a change to columnar in the outer
layer.
 Found in male urethra and ductus
deferens and in parts of pharynx
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Stratified columnar Epi
Transitional Epi
Specialized to change in response to
increased tension. Forms inner lining of
bladder and lines ureters.
 When contracted, there will be several
layers of cuboidal cells. Distended, there
will be less layers.
 Also helps provide a barrier to prevent
urinary tract contents from diffusing back
in to the internal environment.
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Transitional Epi