How are hormones moved between an endocrine gland and its target cells?

How are hormones moved between an endocrine gland and its target cells?

• A. Direct diffusion
• B. Released into interstitial fluid, then blood, and bind to target cells
• C. Carried by nerves
• D. Secreted into ducts

Answer: (B)

Endocrine signaling moves hormones by releasing them into the interstitial fluid around the gland, where they enter nearby capillaries, travel through the bloodstream, and reach distant target cells that have specific receptors. Once bound to those receptors, hormones trigger the appropriate cellular responses that regulate processes like metabolism and growth. This differs from direct diffusion, which would require the cells to be nearby, and from neural signaling, which uses nerves and synapses rather than the bloodstream. Secretion into ducts applies to exocrine glands and sends substances to surfaces rather than into the circulatory system.

Endocrine signaling moves hormones by releasing them into the interstitial fluid around the gland, where they enter nearby capillaries, travel through the bloodstream, and reach distant target cells that have specific receptors. Once bound to those receptors, hormones trigger the appropriate cellular responses that regulate processes like metabolism and growth. This differs from direct diffusion, which would require the cells to be nearby, and from neural signaling, which uses nerves and synapses rather than the bloodstream. Secretion into ducts applies to exocrine glands and sends substances to surfaces rather than into the circulatory system.