What is the primary role of endocrine glands?

• A. Produce digestive enzymes
• B. Transport oxygen in the blood
• C. Filter waste products from the blood
• D. Secrete hormones into the bloodstream to regulate bodily functions

Answer: (D)

Endocrine glands release hormones into the bloodstream to regulate numerous bodily functions. These chemical messengers travel to distant target organs and tissues, coordinating processes like metabolism, growth, reproduction, and overall homeostasis. That's why their primary role is to secrete hormones into the bloodstream to regulate bodily functions.

This differs from producing digestive enzymes, which are exocrine products released into the digestive tract to aid digestion. It also isn’t about transporting oxygen, which is handled by red blood cells with hemoglobin. And it doesn’t involve filtering waste, a job mainly done by kidneys and liver.