Goblet cells are long, slender cells found in most human organs that are almost entirely responsible for the production of mucus. They occur most predominantly in the respiratory tract and they play an important role when it comes to helping the immune system flush out foreign bodies like pollen and smoke, as well as viruses like that responsible for the common cold. The mucus they secrete is also an important part of digestive balance and can help food move through the stomach, intestine, and colon.
These sorts of cells get their name from their basic shape, which to many people looks like a goblet: narrow at the bottom, but broadening near the top. The shape is sometimes compared to a tulip or bell, too. Typically the cell’s nucleus and other organelles are found in the narrow base, whereas the mucus-secreting glands and granules are located in the larger, wider end.
Depending on how the cells are being viewed, the larger end may seem wider than it actually is; most scientists find that the “cup” end of the goblet can get squished and stretched when the cells are prepared for microscope slides, which can make them appear quite a bit broader than in fact most actually are. When they are at work in the body, these cells often seem more or less tubular. One end is slightly more bulbous, but the difference isn’t always as pronounced as it might otherwise seem.
What They Do
Goblet cells work primarily through merocrine secretion, in which highly concentrated mucus-filled vesicles build up in the cell. Once they are released, something known as the “Golgi membrane” fuses with the cellular membrane, and the mucus is released. It’s usually released in a very concentrated form, though, and often comes out as a gel. That gel reacts with fluids and water outside of the cell and can expand to up to 500 times its original volume almost instantly — in approximately 0.02 seconds, to be precise.
Where They’re Located
These sorts of mucus-secreting cells are very prominent in the lungs, nose, and sinuses, and are also widely present all along the digestive tract. These are the places that often have the most use for mucus. Most organs also contain them in their lining, too, though. While mucus is most commonly used to flush things out, it can also be a lubricant that can assist in various organ functions. Outside of the respiratory and digestive tracts goblet cells are usually widely outnumbered by other types of cells, but they are almost always present in at least some degree.
Importance to the Immune System
Mucus plays a very important role in healthy immune function. It is usually stimulated by some sort of an external irritation, such as digestive acids in the intestine or smoke in the respiratory tract, and helps to flush the foreign substance out of the body and away from any organs or tissues it may be able to harm.
Many diseases and illnesses can be stopped or aided by mucus secretions, which is another way these cells help the immune system. The common cold and influenza viruses, for example, are both usually characterized by an increase in systemic mucus production. Other more serious diseases like chronic obstructive pulmonary disease or cystic fibrosis can also involve not only increased mucus production but also elevated numbers of these cells themselves as the body mounts its defense.
It’s generally pretty rare for a person’s goblet cells to not function properly, but it can happen. Most of the time this is due to some sort of accident or injury that damages some of the tissues where the cells occur in the highest densities; some diseases and aggressive treatments, including chemotherapy and radiation, might also impact how prolific these cells are as well as how effective they can be. People with low mucus secretions often have a harder time getting over illnesses and may have a range of digestive and respiratory problems, too.
Sometimes these cells begin reproducing and growing in places where a lot of mucus isn’t needed, which can also be problematic. When they start colonizing the esophagus, for instance, a range of problems can ensue. This is often an indication of intestinal metaplasia, a phenomenon in which the lining of the esophagus is gradually replaced by tissue similar to that found in the intestine. Upon biopsy, patients with intestinal metaplasia may be diagnosed with Barret's esophagus, a usually benign condition associated with long-term irritation of the esophageal lining. Barrett's esophagus is most often diagnosed in men over 50 years old who have a history of gastroesophageal reflux disease, and it also can be associated with a slightly increased risk of developing a kind of cancer called esophageal adenocarcinoma.