Problem 2RCQ: How does pressure at the bottom of a body of water relate to... How does pressure at the bottom of a body of water relate to the weight of water above each square meter of the bottom surface? Chapter , Problem is solved.
The mutations that cause carcinoid tumors often affect the MEN1 gene, the same gene responsible for most familial neuroendocrine tumors and neuroendocrine cancers. But not much is known about exactly what causes these gene changes. Doctors do know that carcinoid tumors start out very small and grow slowly. When patients have parts of their stomach or small intestine removed to treat other diseases, taking a close look under the microscope often shows small groups of neuroendocrine cells that look like tiny carcinoids.
An intestinal carcinoid does not usually cause the syndrome unless hepatic metastases have occurred because metabolic products released by the tumor are rapidly destroyed by blood and liver enzymes in the portal circulation (eg, serotonin by hepatic monoamine oxidase).