Final answer:
Trypsinogen is considered an exocrine secretion and ends up in the digestive tract lumen, while secretin is considered an endocrine secretion and ends up in the blood.
Step-by-step explanation:
A chemical like trypsinogen is considered an exocrine secretion because it ends up in the digestive tract lumen. A chemical like secretin is considered an endocrine secretion because it ends up in the blood.