AAMC FL Practice Exam

Which is a distinguishing feature of endocrine glands?

1. They secrete substances through ducts

2. They secrete hormones directly into the bloodstream

3. They primarily produce enzymes

4. They regulate body temperature

The correct answer is: They secrete hormones directly into the bloodstream

Endocrine glands are characterized by their unique method of secretion. Unlike exocrine glands, which release their products through ducts to specific sites, endocrine glands secrete hormones directly into the bloodstream. This method allows the hormones to travel throughout the body and exert their effects on various tissues and organs, facilitating the regulation of numerous physiological processes, including metabolism, growth, and mood. The distinction is critical: while exocrine glands might produce substances such as saliva or digestive enzymes that have a local effect, endocrine glands focus on long-distance signaling through hormones, enabling a more widespread and systemic impact on bodily functions. This direct secretion into the bloodstream is what predominantly defines the role and operation of endocrine glands. In contrast, the other options refer to different functions and characteristics that do not accurately describe endocrine glands' mode of operation.