Epithelial tissue is tightly packed cells and has minimal extracellular matrix. It
covers the body and organ surfaces, lines body cavities and organ cavities, forms glands.
Can be simple (one layer), stratified (2 or more), and pseudostratified (appears layered).
Keratinized: found in epidermis and superficial layer of dead cells. Lacks nucleus and filled with
keratin.
Non keratinized: all cells are alive and kept moist with secretions. Visible cell nuclei. Found in
oral cavity, esophagus, vagina, and anus
Functions: Physical protection, selective permeability, secretion, and sensation.
Types
Characteristics
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1. Simple Squamous
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One cell layer, irregular floor tiles, with
a buldging nucleus; attached to
basement membrane directly
Thinnest possible barrier for diffusion,
filtration, and secretion from serous
membranes to occur
Location: lines air sacs in lungs
(alveoli), lymph vessels and lumen
vessels (endotheliam), and serous
membranes of body cavities
(mesothelium)
2. Simple Cuboidal
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Absorbs and secretes between filtrate
and blood
Secretory tissue of most glands and
small ducts
Location: kidney tubules, thyroid
gland follicles, surface of ovary,
secretory regions of ducts and
glands
3. Non-cilated Simple Columnar
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Taller than they are wide, nucleus in
basal region, apical regions may have
microvilli, may contain goblet cells that
secrete mucin
Absorption and secretion; mucin
Location: inner lining of digestive
tract (stomach, small and large
intestine
4. Cilated Simple Columnar
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Secrete mucin and help movement in
apical surface by cilia; oocyte
movement through uterine tube
Lining bronchioles of lung and
uterine tube
5. Cilated Psuedostratified Columnar
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Singles layer of cells with varying
heights, all cells connect to basement
membrane BUT not all cells reach
apical surface
Goblet cells (secrete mucin through
ducts making moist) and cilia
Protection, move mucin along apical
surface by cilia
Cilated form in most of upper resp.
Tract including trachea
Line larger air ways of respiratory,
nasal cavity, pharynx, trache,
bronchi, and larynx
6. Noncilated Psuedo. Columnar
7. Keratinized Stratified Squamous
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Single layer with varying heights
Protection
RARE - lining of the part of male
urethra and epididymis
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Multiple cell layers. Apical cells are
dead and filled with protein keratin
Protect underlying tissue from
abrasion
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7. Non-Keratinized
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Epidermis of skin
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Superficial cells alive and kept moist
Protection of underlying tissue
Lines oral cavity, phayrnx, larynx,
esophagus, vagina, and anus
Withstand abrasion from ingested
materials
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8. Stratfied Cuboidal
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Two or more layers
Protect and secrete
Ducts of most exocrine glands and
ovarian follicles
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Protect and secrete
Large ducts of salivary glands,
conjunctiva covering eye, and
membranous part of male urethra
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Appearance varies depending on if
relaxed or distended.
Relaxed: apical cells are large and
rounded.
Distended: flattended cells at apical
surface some binucleated
Urine elimination
Bladder, ureters, and part of
9. Stratified Columnar
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10. Transitional
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urethra