Questions: a. secrete hormones into the bloodstream, whereas secrete substances into ducts and onto the skin or the lumen of a hollow organ. b. Goblet cells and mammary glands are both exocrine glands-how are they similar and how are they different?

a. The answer is: Endocrine glands secrete hormones into the bloodstream, whereas exocrine glands secrete substances into ducts and onto the skin or the lumen of a hollow organ.

Explanation:

• Endocrine glands release hormones directly into the bloodstream, which then travel to target organs or tissues to exert their effects. Examples include the thyroid gland and adrenal glands.
• Exocrine glands release their secretions through ducts to the surface of an organ or onto the skin. Examples include sweat glands and salivary glands.

b. Goblet cells and mammary glands are both exocrine glands.

Similarities:

• Both goblet cells and mammary glands are classified as exocrine glands because they secrete their products through ducts or onto surfaces.
• They both play roles in secretion: goblet cells secrete mucus, while mammary glands secrete milk.

Differences:

• Goblet cells are unicellular glands found in the lining of the intestines and respiratory tract, where they secrete mucus to protect and lubricate surfaces.
• Mammary glands are multicellular and more complex, found in the breast tissue, and are responsible for producing and secreting milk, primarily during lactation.

In summary, while both goblet cells and mammary glands are exocrine glands, they differ in structure, location, and the substances they secrete.