Tissue Types

Key Terms
• Differentiation = produces specialized cells
during embryonic development
• Tissues = groups of cells which are similar in
structure and which perform common or
related functions
• Histology = the study of tissues

Four Basic Kinds of Tissues
• Epithelial Tissue
• Connective Tissue
• Muscle Tissue
• Nervous Tissue

Epithelial Tissue
• Locations:
– Covers the body
– Lines organs, body cavities, and ducts
– Forms glands
• Functions:
– Protection from injury and microbial invasion
– Regulates permeability
– Secretes fluids to lubricate structures

Characteristics:
• Avascular (no blood vessels)
• Cells may show polarity (apical & basal surface,
they are chemically and structurally different
from one another)
• A basement membrane attaches epithelia to
underlying connective tissues
• High rate of cell division (allows repair by
sloughing off dead or injured cells, important
because epithelium is exposed to physical stress)
Epithelial Tissue

The Polarity of Epithelial Cells

• Number of cell layers pg 113
– Simple (single layer)
– Stratified (several layers)
– Pseudostratified (nuclei are at different levels & not
all cells reach the apical surface)
• Shape of cells (draw, location, function)
– Squamous (thin, flat, irregular cells) pg 115
– Cuboidal (cube shaped cells) pg 116
– Columnar, ciliated and nonciliated (tall & slender
cells) pg 116, 117
– Transitional (change shape from flat to cuboidal and
back) pg 119
Classification of Epithelia

Squamous Epithelia

Cuboidal Epithelia

Cuboidal Epithelia Cont.

Special Cuboidal Epithelia:
Transitional Epithelia
cells can stretch

Columnar Epithelia

Columnar Epithelia

Columnar Epithelia

Many epithelia contain gland cells that produce
secretions
Exocrine glands:
– Produce secretions such as mucus and/or watery
solution through ducts onto the epithelial surface
Endocrine glands:
– Ductless, release secretions directly into bloodstream
Glandular epithelia

Exocrine vs.
Endocrine
Glands

Examples of Exocrine Glands

Time to Review
Simple squamous
epithelium (lining of body
cavities)
Simple cuboidal epithelium
(lining of glands and ducts)

Simple columnar
epithelium (lining of
stomach, intestines)

Stratified squamous epithelium (skin)

Simple
columnar
epithelium
(lining of
digestive tract)

Simple cuboidal
epithelium
(lining of ducts in
kidneys)

Simple squamous
epithelium (lining
of the heart)

Pseudostratified
columnar
epithelium
(lining of nasal
cavity)

Transitional
epithelium (urinary
bladder)

Stratified
squamous
epithelium (lining
of mouth)

Type of Tissue Function Location
Pseudostratified
columnar
removing dust and particles
from airways, has cilia
lines the respiratory
passageways
Simple Columnar Absorption
lines the uterus and
most organs of the
digestive tract
Simple Cuboidal Secretion and Absorption
glands, kidney tubules,
ovaries
Simple Squamous Diffusion and Filtration
lungs, walls of
capillaries and vessels
Stratified Squamous Protects underlying cells
skin(keratinized) and
the throat, vagina,
mouth (soft)
Stratified Cuboidal Protection
lines ducts of the
mammary glands,
sweat glands, pancreas
Stratified Columnar Protection, secretion
male urethra and vas
deferens, parts of the
pharynx
Transitional
(unstretched)
Specialized to become
distended
urinary tract