Final answer:
Endocrine glands are ductless and secrete hormones directly into the blood, whereas exocrine glands release secretions through ducts onto an epithelial surface or organ lumen.
Step-by-step explanation:
Differences Between Endocrine and Exocrine Glands
The main characteristic that describes the difference between endocrine and exocrine glands is that endocrine glands are ductless and release their hormones directly into the bloodstream. On the other hand, exocrine glands release their secretions through ducts onto an epithelial surface or into the lumen of an organ.
Examples of endocrine glands include the thyroid and pituitary glands, which secrete hormones like thyroxine and growth hormone, respectively, into the blood. By contrast, exocrine glands include the salivary glands and pancreas, which releases substances like saliva and digestive enzymes through their ducts.
The pancreas is unique because it functions as both an endocrine and an exocrine gland. The endocrine part of the pancreas releases hormones like insulin into the bloodstream, whereas the exocrine part secretes digestive enzymes into the small intestine via a duct.