Epithelial Tissue

TISSUES
 A collection or groups of similar cells performing a definite function.
4 fundamental tissues in the animal body:
1. Epithelial tissue – forms the covering or lining of body surfaces

2. Connective tissue – forming the principal supporting tissue
3. Muscular tissue – responsible for body movements
4. Nervous tissue – specialized tissue for the transmission of stimuli
EPITHELIAL TISSUE (EPITHELIUM)
 Made up of cells that are compactly arranged and rested on a basement membrane.
 Lines all free body surfaces, internal and external including body cavities.
 Avascular and capable to regenerate
Functions:
1. Protection – skin
2. Secretion – salivary glands
3. Absorption – small intestines
4. Excretion – sweat glands
5. Sensation – taste buds
6. Reproduction – ovary and testes
Types of epithelium:
1. Covering/ lining epithelium – found in sheets that cover body structures (outer layer of skin) or line body
spaces (lining of the stomach).
2. Glandular epithelium – forms the functional portions of the exocrine and endocrine glands.
Classifications of epithelial tissue (categorized by its structure)
I. According to the # of cell layers

1. Simple – made up of 1 cell layer
2. Stratified – made up of more than 2 layers of cell
3. Pseudostratified – made up of only 1 layer of cell, but with different height
4. Transitional – simple – stratified
II. According to the shape of the cell

1. Squamous – flat, scale-like cells with serrated border
2. Cuboidal – cells with an equal height and width
3. Columnar – tall, narrow, prismatic cells, the height is greater than width
a. Simple
b. Ciliated
III. According to functions

1. Protective – guards the body from external injury and infections
2. Sensory – for reception of stimuli
3. Germinal – for production of sex cells
4. Glandular – secretes products for body use
1
SIMPLE EPITHELIAL TISSUE
 A mere single layer cell thick
 Type of epithelium located where diffusion, filtration, and secretion are principal functions
1. Simple squamous epithelium

 Composed of flat, irregularly shaped cells
that are tightly bound together
 Lines the air sacs of lungs, kidneys(where
filtration occurs), blood vessels, body
cavities and coverings of viscera
2. Simple cuboidal epithelium

 Composed of tightly-fitted cube shaped cells
 Found lining small ducts and tubules that
have excretory, secretory and absorptive
functions
 Lines the ovaries, kidneys, ducts of salivary
glands and pancreas
3. Simple columnar epithelium

 Lines the inside walls of stomach and small
intestine
 The tissue consists of “goblet cells”
(secretes lubricative and protective mucus
along the free surfaces of the tissue).
4. Simple ciliated columnar epithelium

 Characterized by the presence of “cilia”
along the free surface
 Lines the female uterine tubes to move the
egg cell into uterus
5. Pseudostratified ciliated columnar epithelium  Lines the trachea and bronchial tubes,
 Also known as the “respiratory epithelium” urinary and reproductive tracts in male
 Consists of numerous goblet cells
2
STRATIFIED EPITHELIAL TISSUE
 Consists of 2 or more layers of cells, the cell divides rapidly

 Too thick to absorb or secrete
 It has a protective function
1. Stratified squamous epithelium

 Forming the skin layer, lining the openings
of the body – mouth, anus, vagina
 Forms the 1st line of defense against the
entry of disease causing organisms
a. Keratinized stratified squamous epithelium

- Contains “keratin”, it makes the epidermis of the
skin somewhat waterproof and protects it from
bacterial invasion
- The outer layers of the skin are dead, but
glandular secretions keep them soft.
b. Non-keratinized stratified squamous

epithelium
- Also known as the “mucosa”, which is well
adapted to withstand moderate abrasion but not
fluid loss
- The cells on exposed surface are alive and
always moistened
- Lines the mouth, throat, nasal cavity, vagina and
anal canal.
2. Stratified cuboidal epithelium

 It has a limited distribution in the body
 Lines the large ducts of sweat glands,
salivary glands and pancreas
3
3. Transitional epithelium
 Similar to non keratinized stratified
squamous epithelium
 Transition between simple and stratified
variety
 Restricted only to urinary system that lines
hollow organs capable of distention –
urinary bladder, ureters
4
5

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TISSUES

 A collection or groups of similar cells performing a definite function.

4 fundamental tissues in the animal body:

1. Epithelial tissue – forms the covering or lining of body surfaces

EPITHELIAL TISSUE (EPITHELIUM)

Classifications of epithelial tissue (categorized by its structure)

I. According to the # of cell layers

II. According to the shape of the cell

III. According to functions

 A mere single layer cell thick

1. Simple squamous epithelium

2. Simple cuboidal epithelium

3. Simple columnar epithelium

4. Simple ciliated columnar epithelium

 Consists of 2 or more layers of cells, the cell divides rapidly

1. Stratified squamous epithelium

a. Keratinized stratified squamous epithelium

b. Non-keratinized stratified squamous

2. Stratified cuboidal epithelium

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