Final answer:
After a deer dies, the enzyme pepsin, which aids in protein digestion within its stomach, can begin to autolyze the stomach lining. This is because the regulatory mechanisms that prevent self-digestion are no longer active postmortem.
Step-by-step explanation:
The question pertains to whether the pepsin that aids in the digestion of food within a deer's stomach will begin to break down the stomach itself after the deer dies. During the life of the deer, protein digestion is a critical function carried out by pepsin in the stomach chamber.
Pepsin is secreted by chief cells as pepsinogen and converts to active pepsin in the presence of hydrochloric acid (HCl), produced by parietal cells. This acidic environment is necessary for pepsin's optimum function, which starts breaking down proteins into smaller polypeptides. This process is a part of a larger cascade that eventually leads to the absorption of amino acids, the building blocks of proteins.
After death, the regulatory mechanisms that control stomach acid production and enzyme secretion cease. Without these controls, the stomach's highly acidic environment combined with active pepsin could begin to autolyze, or self-digest, the stomach lining. This is because pepsin is an enzyme that cleaves peptide bonds in proteins, which are also present in the tissues of the stomach itself. Therefore, after death, the pepsin can indeed start breaking down the stomach since it is no longer protected by living physiological processes that prevent self-digestion.