Final answer:
Proteases are secreted by the pancreas, stomach, and small intestine. They play a crucial role in the digestion of proteins by breaking them down into smaller peptides or amino acids. Salivary glands, however, do not secrete proteases.
Step-by-step explanation:
The organs that secrete proteases, which are enzymes that break down proteins into smaller peptides or amino acids, include the pancreas, stomach, and the small intestine. The pancreas releases proteases like trypsin, chymotrypsin, and elastase as part of the pancreatic juice, aiding in protein digestion. The stomach secretes pepsin, an enzyme that cuts proteins into smaller polypeptides. The small intestine continues the process by further breaking down proteins with additional enzymes released from its walls and those from the pancreatic juice. Conversely, salivary glands do not produce proteolytic enzymes and hence are not involved in protein digestion.