Final answer:
The 'take off' of the right upper lobe bronchus is the point where it branches off from the right primary bronchus, shortly after the primary bronchus enters the lung at the hilum.
Step-by-step explanation:
The term 'take off' refers to the point where the right upper lobe bronchus branches off from the main bronchus. In the human respiratory system, the trachea divides into the right and left primary bronchi. The right primary bronchus is larger and more vertical due to the presence of three lobes in the right lung as opposed to two in the left lung. The right primary bronchus then further divides into secondary bronchi, with one going to each lobe of the lung. Within the right lung, the upper lobe bronchus is the bronchus that serves the superior lobe. It branches off from the right main bronchus soon after it enters the lung at the hilum, which is a concave region where various structures such as blood vessels, lymphatic vessels, and nerves also enter the lung. Each secondary bronchus then subdivides into tertiary bronchi that continue to branch into bronchioles, ultimately leading to the alveoli responsible for gas exchange.