.png){kind=icon}
Q1. Discuss the role of mucus in the protection of the alimentary tract.
A. Mucus is not a one-size-fits-all secretion. Different parts of the alimentary tract secrete different mucins that produce a luminal coating of variable viscosity. For example, compare the watery mucus of saliva with that of the colon. Furthermore, there are specialized mucous channels in the gastric glands that allow separation of hydrogen ions and pro-enzymes in the gastric glands. Various cell types produce mucus, from the mucus-neck cells and surface mucus cells of the gastric mucosa, the goblet cells of the small and large intestine and the mucus glands of the salivary glands.
Q2. Why might diet have such an effect on the relative risk of developing cancers of the alimentary tract?
A. Cancer is a disease found predominantly in epithelium, a tissue with high rates of cell turnover and therefore susceptible to the effects of any chemical mutagens that might be ingested, or damage associated with chronic inflammation. There are many links between not only classes of foods (alcohol in general, or processed meat) but also specific foods or ingested substances, such as the link between betel-nut chewing and oral squamous cell carcinoma. Any food habit that results in chronic damage to the mucosa may increase the risk of initiating potentially malignant changes that may progress to invasive cancer.