I was reading pancreatic digestive enzymes from a Textbook of Medical Physiology and I came across Trypsin Inhibitor, it stated that It is important that the proteolytic enzymes of the pancreatic juice not become activated until after they have been secreted into the intestine because the trypsin and the other enzymes would digest the pancreas itself.... ....substance called trypsin inhibitor. This substance is formed in the cytoplasm of the glandular cells, and it prevents activation of trypsin both inside the secretory cells and in the acini and ducts of the pancreas.
It also states that 'When first synthesized in the pancreatic cells, the proteolytic digestive enzymes are in the inactive forms trypsinogen, chymotrypsinogen, and procarboxypolypeptidase, which are all inactive enzymatically. They become activated only after they are secreted into the intestinal tract.'
My question is, why is Trypsin Inhibitor secreted if trypsin is already secreted as trypsinogen and can only be activated in intestine.