Epithelial cells are specialized cells which line many different kinds of tissue. Columnar epithelial cells are named because they are somewhat rectangular in shape and resemble a column in their orientation. Columnar epithelial cells are often specialized so that they can have a variety of different functions in the tissues which they line.
Columnar epithelial cells are often found at the linings of certain sensor organs, the University of the Western Cape explains. Columnar epiothelial cells can be found in the linings of the ears, nose and on the taste buds of the tongue. These cells are designed to respond to stimuli, which can come in the form of sound waves or as molecules which are able to bind to these specialized epithelial cells. These cells are able to transmit information about their surroundings to nerve cells, which then convey sensory information to the brain.
Columnar epithelial cells can also be involved in secretion, notes the University of Florida Physician Assistant Program. Columnar epithelial cells can be designed to manufacture and excrete different substances. Columnar epithelial cells can be modified to become glandular or goblet cells. Sometimes these cells secrete mucus, gastric juices or tears into different ducts within the body. These are known as exocrine glands because the secretions affect the surrounding tissue. Columnar epithelial cells can also be found in endocrine glands, which make hormones which are then secreted into the blood. Endocrine glands can affect many different tissues throughout the body because of their connection to the blood stream.
Columnar cells also have an important role in the digestive tract, Southern Illinois University explains. These cells line the intestines and are responsible for absorbing nutrients from digested food. Columnar epithelial cells in these cases often have multiple finger-like projections, which increase the surface area of the cells. A large surface area is necessary to maximize the efficiency of the absorption of these specialized cells.
A specialized kind of columnar epithelium, known as ciliated columnar epithelium, can be found in the lining of some organs, such as the fallopian tubes and in the lungs. Cilia are specialized bundles of protein which can move together to help propel material in one direction. In the lungs these cells help propel mucus and other materials out of the lungs and up into the throat. In the fallopian tubes cilitated columnar epithelial cells move eggs through the fallopian tubes and into the uterus.
Like all epithelial cells, columnar epithelial cells are designed to protect the tissues which they line. Columnar epithelial cells are rather thick, which allows them to withstand mild amounts of damage. In some cases columnar cells can be replaced by more hardy forms of epithelium if they experience significant damage. This can occur with chronic acid reflux, leading to a condition known as Barrett's esophagus.