Introduction[edit | edit source]
Goblet cells are a specialized type of epithelial cell that secrete mucins (any of the class of glycoproteins found in mucus e.g. saliva, gastric juice, secreted by mucous membranes) which are significant components of mucus. They are most often found in the respiratory and gastrointestinal tracts, where they make up part of the surface epithelium. The secretion of mucus in these tracts lubricates and protects the lining of the organs. This mucous barrier also aids in the preservation of the epithelium.
- Goblet cells have a very prominent morphology; having the nucleus, mitochondria, Golgi body, and the endoplasmic reticulum at the basal portion of the cell. The rest of the cell is filled with mucus in secretory granules.When fixed, these cells appear to have a narrow base and expanded apical portion that extends up to the lumen
- Clinically, goblet cells are associated with respiratory diseases and inflammatory bowel diseases.
Image 1: Goblet cells (shown in blue), then underlying connective tissue
Function[edit | edit source]
Goblet cells are widely distributed in the different epithelia of many organs. In particular they are found lining the epithelium of respiratory organs (trachea, bronchioles, and bronchi), digestive organs (small and large intestines), and the conjunctiva in the upper eyelid. Among all of these organs, they are most abundant in the intestines
Intestinal: Goblet cells are a type of intestinal mucosal epithelial cell, the primary function of goblet cells is to synthesize and secrete mucus.
- These mucins help neutralize the acids produced by the stomach. They also help in lubricating the epithelium for the easier passage of food.
- Although the production of mucus is the main function of them, recent studies have shown that goblet cells in the small intestine can accumulate and uptake antigens (toxins that induces an immune response).
- In the large intestine, the formed mucus blanket/barrier inhibits inflammation by preventing the passage of luminal bacteria and food-derived antigens from passing through it. Such phenomenon is called as the oral tolerance
Respiratory Tract: While most cells in the respiratory tract are ciliated columnar cells, there are some goblet cells present in the epithelia. In these locations, they are situated with their apices protruding into the lumen in order to react rapidly whenever a chronic airway insult happens or a foreign body is inhaled. New evidence revealed that the mucins produced by the goblet cells are responsible for the trapping and transport of the inhaled foreign bodies (i.e. allergens, particles, and microorganisms).
Secretion[edit | edit source]
Mucous secretion is preceded by a stimuli. Along with the secretory granules, they secrete the mucus via exocytosis (process where the contents of the vacuole is released).
- When inside the goblet cell, the mucus is initially in a condensed state. However when it gets released, it dramatically and instantaneously expands.
- The mucin gel in goblet cells can expand up to 500 times its original volume in just 20 milliseconds.
Pathophysiology[edit | edit source]
Goblet cells are implicated in a few diseases either due to their increased activity (hyperproduction of mucus), increased number, or aberrant presence at new sites.
- parasitic intestinal infections
- Mucus hypersecretion as a result of goblet cell hyperplasia is a symptom of asthma and chronic obstructive pulmonary disease. Hyperplasia refers to areas where the excessive proliferation of goblet cells occurs in an area they are normally present, such as large airways. As a result of this goblet cell proliferation, the usual protective role of goblet cell mucin secretion transforms into a pathophysiological role. Sputum is the thick mucus (sometimes called phlegm) which is coughed up from the lungs.
- immune cells, and other types in the airways. Inflammatory pathways may attenuate or worsen the condition. Timing for goblet cell metaplasia may last from a few weeks to decades. Smoking cigarettes, inhaling biomass fuels, chronic bronchitis, environmental allergens that trigger asthma, and mutations of cystic fibrosis transmembrane conductance regulator may cause lung diseases with goblet cell metaplasia.
- Two major bowl inflammatory diseases that may involve goblet cells are Crohn disease and ulcerative colitis. In ulcerative colitis, goblet cell number and size drastically decrease. Mucin, the main product of goblet cells, plays an essential role in maintaining protective mucus barriers, and the breakdown of these barriers is thought to result in colitis eventually.
Physiotherapy Relevance[edit | edit source]
References[edit | edit source]
- Biology on line Mucins Available:https://www.biologyonline.com/dictionary/mucin ( accessed 9.7.2021)
- Dao DPD, Le PH. Histology, Goblet Cells. [Updated 2021 Jan 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-.Available:https://www.ncbi.nlm.nih.gov/books/NBK553208/ (accessed 9.7.2021)
- Bioexplorer Goblet Cells Available:https://www.bioexplorer.net/goblet-cells.html/ (accessed 9.7.2021)
- Biology Dictionary Goblet Cells Available:https://biologydictionary.net/goblet-cells/ (accessed 9.7.2021)