What is pepsin and mucus

 Proteins are digested by the enzymes called as proteases. Proteases are secreted in the stomach to initiate protein digestion. Pepsin in stomach also aids in protein digestion. During intestinal digestion of proteins, trypsin plays a vital role. Protein digestion is brought over by pepsin, trypsin and other exopeptidases.
*Pepsin is a digestive enzyme secreted by the chief cells in the stomach in its inactive form called as pepsinogen.It gets activated to pepsin in the presence of HCl. Proteins are converted into peptides by the action of pepsin.   Mucus is a slippery secretion produced by mucous membranes. Mucous fluid is typically produced from cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing antiseptic enzymes,immunoglobulins, inorganic salts, proteins such as lactoferrin, and glycoproteins known as mucins that are produced by globlet cells in the mucous membranes and submucosal glands. This mucus serves to protect epithelial cell in the respiratory, gastrointestinal, urinogenital, visual and auditory systems in mammals. A major function of this mucus is to protect against infectious agents such as fungi, bacteria and viruses. The average human body produces about a litre of mucus per day.