Fundamentals of Anatomy and Physiology

96

Characteristics and Location

Columnar epithelial cells^
Elongated, with the nucleus generally near the
bottom and often ciliated on the outer surface;
they line the ducts, digestive tract (especially
the intestinal and stomach lining), parts of the
respiratory tract, and glands.

Chapter 5

Morphology

(A)

Source^

Associ at es/ Sci ence^

(^)
Bi ophot o^
©^
( B)^
Photo^
,^
®^

(B)

Learni ng^

Cengage^

©^

( A)^

Figure 5- 3 Views of columnar
epithelium.

(A)

Figure 5- 4

(^) Source
Gschmeissner/Science
Steve © (A) Photo (B)
Examples of (A) pseudostratified ciliated, columnar epithelium and (B) transitional epithelium.
Source
Associates/Science Biophoto ©
(B) Photo
Figure 5-4A is an example of pseudostratified ciliated,
columnar epithelium. We find this tissue in the throat,
trachea, and bronchi of the lungs. Transitional
epithelium consists of several layers of closely packed,
flexible, and easily stretched cells (Figure 5-4B). When the
surfaces of the cells are stretched, as in a full bladder, the
cells ap-pear squamous or flat but when the tissue is
relaxed, as in an empty bladder, the layers of cells look
ragged like the teeth of a saw. This type of epithelium lines
the pelvis
of the kidney, the ureters, the urinary bladder, and the
upper part of the urethra.
Classification Based on Function
Epithelial tissue can also be named or classified based on
its function. The terms mucous membrane, glands,
endothelium-, and mesothelium all refer to epithelial tissue.