Which of the following is not component of acinus?: (A) Pulmonary lobule, (B) Respiratory bronchioles, (C) Alveolar ducts, (D) Alveolar sac
Answer is A. Ans. is `a' i.e., Pulmonary lobule o Pulmonary lobule is not a component of acinus, rather cluster of 3-5 terminal bronchioles with acinus form pulmonary lobule. Respiratory tract anatomy o Progressive branching of bronchi forms bronchioles. o Fuher branching of bronchioles leads to terminal bronchioles. o Terminal bronchiole emnate into respiratory bronchioles. o Respiratory bronchioles proceed into the alveolar ducts, wich immediately branch into alveolar sacs (alveoli). o The pa of lung distal to the terminal bronchiole is called acinus, i.e., respiratory bronchiole, alveolar duct and alveolar sac. o A cluster of three to five terminal bronchioles, each with its appended acinus, is usually referred to as pulmonary lobule. o So, pulmonary lobules include cluster of three to five terminal bronchioles with its respiratory bronchioles, alveolar ducts and alveolar sacs