GLOSSARY

Endocrinology studies hormones, glands and their related disorders.

Hormones are chemical signals whose effects depend on target cells and appropriate receptors. Endocrine generally describes communication through blood, while local and neural signals also contribute. One substance can have several roles and sources. Calling something a metabolic or appetite hormone does not imply an exclusive effect; interpretation requires the signaling network, food and activity rather than assigning the body's response to one molecule alone.

Synthesis, storage, secretion, transport and clearance are distinct processes. Blood concentration reflects entry and removal rather than directly measuring secretion; exercise-related plasma-volume changes can also affect it. Half-life depends on hormone form and method and is not identical to the duration of all effects. Comparisons therefore need sampling time, previous food and recent activity standardized or recorded rather than interpreting isolated concentration differences without context.

Sensitivity is response to a given signal and is not identical to hormone concentration or receptor number. Receptor abundance, binding and downstream signaling can each alter response. Maximum responsiveness also differs from a shift in sensitivity. One blood value cannot describe all tissue receptors; assay type and target tissue are needed to interpret resistance or sensitivity rather than treating these as directly interchangeable concentration measurements.