Home/Topics/General Medical Terms/lobe General Medical Terms Brain & Nervous System Lungs & Breathing Digestive System & Nutrition Hormones, Diabetes & Metabolism lobe Listen Save Share Print Meaning of lobe: A portion of an organ, such as the liver, lung, breast, thyroid, or brain. Definition of lobe A portion of an organ, such as the liver, lung, breast, thyroid, or brain. Written and maintained by James Murray · Last updated July 21, 2026 Educational reference, not medical advice. Read the limitations. Keep exploringRelated termsMore in General Medical Terms → Procedures & Surgery lobectomy A lobectomy removes one entire lobe of an organ, most often the lung, sparing the rest of the organ and its function. Read definition → Biological & Chemical Substances serotonin The brain and gut supplies are separate, because the molecule cannot cross from blood into brain tissue, and each pool works on its own. Read definition → Anatomy & Physiology autonomic nervous system Two opposing divisions, one for action and one for rest, keep heart rate, blood pressure, and digestion balanced without any conscious effort. Read definition → Biological & Chemical Substances 5-hydroxytryptamine A hormone found in the brain, platelets, digestive tract, and pineal gland. Read definition →
Procedures & Surgery lobectomy A lobectomy removes one entire lobe of an organ, most often the lung, sparing the rest of the organ and its function. Read definition →
Biological & Chemical Substances serotonin The brain and gut supplies are separate, because the molecule cannot cross from blood into brain tissue, and each pool works on its own. Read definition →
Anatomy & Physiology autonomic nervous system Two opposing divisions, one for action and one for rest, keep heart rate, blood pressure, and digestion balanced without any conscious effort. Read definition →
Biological & Chemical Substances 5-hydroxytryptamine A hormone found in the brain, platelets, digestive tract, and pineal gland. Read definition →