Symptoms of a urinary tract infection (UTI) are similar in men, women, and children. Early symptoms and signs are usually easy to recognize and primarily involve pain, discomfort, or burning when trying to urinate.
Protein digestion begins in the stomach with the action of an enzyme that we previously learned about called pepsin. Pepsin is the active protein-digesting enzyme of the stomach. When pepsin acts on the protein molecule, it breaks the bonds that hold the protein molecule together, called peptide bonds.
Digestive enzymes are diverse and are found in the saliva secreted by the salivary glands, in the stomach secreted by cells lining the stomach, in the pancreatic juice secreted by pancreatic exocrine cells, and in the intestinal (small and large) secretions, or as part of the lining of the gastrointestinal tract. Pepsinogen is then activated by the stomach acid into its active form, pepsin. 2  Pepsin breaks down the protein in the food into smaller particles, such as peptide fragments and amino acids. 3  Protein digestion, therefore, first starts in the stomach, unlike carbohydrate and lipids, which start their digestion in the mouth.