This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Functional Anatomy - Respiratory System, Subject name: Physiology
Which of the following is true for tracheobronchial luminal neuroendocrine cells? 
Select and explain. 
A. Contain serotonin, B. Contain catecholamines, C. Respond to decrease in pO2, D. Have only cholinergic nerve supply
A: Contain serotonin
Answer: A: Contain serotonin 
Explanation: Ans. a. Contain serotonin (Ref: Ganong 24/e p638: Ganong 22/e p482-483)'Cells 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 22/e 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