<prompt> Which of the following is true for tracheobronchial luminal neuroendocrine cells?Contain serotoninContain catecholaminesRespond to decrease in pO2Have only cholinergic nerve supply  <response>: Ans. a. Contain serotonin Ref: Ganong 24e p638: Ganong 22e p482-483Cells that manufacture amines in addition to polypeptide are sometimes called APUD cells Amine Precursor Uptake and Decarboxylase or neuroendocrine cells and are found in lungs and other organs in addition to the GIT. They are the cells that form carcinoid tumors.- Ganong 22e p482-483Biologically Active Substances Metabolized by the LungsSynthesized and used in lungs: SurfactantSynthesized or stored and released into the blood: Prostaglandins Histamine KallikreinPartially removed from the blood: Prostaglandins Bradykinin Adenine nucleotides Serotonin Noeepinephrine AcetylcholineActivated in the lungs: Angiotensin I to angiotensin II 