The trachea, bronchi and bronchioles form the tracheobronchial tree â a system of airways that allow passage of air into the lungs, where gas exchange occurs.he trachea marks the beginning of the tracheobronchial tree. It arises at the lower border of cricoid cartilage in the neck, as a continuation of the larynx. By Bibi Saint-Pol [CC BY-SA 3.0], via Wikimedia Commons. Fig 1.0 â Overview of the tracheobronchial tree.
While relative masses are nice if you want to compare protons, neutrons and electrons to one another, it doesn't tell you what the actual masses of these particles are. In kilograms, the masses are: Neutron = 1.6749286*10-27 kg.
Remember that isotopes have the same number of protons but different numbers of neutrons. The most common isotope of hydrogen has only one proton and zero neutrons. If both protons and neutrons have a mass of about 1 amu (atomic mass unit), the mass of this atom would be about 1 amu (just the mass of the proton). This isotope of hydrogen has a special name, protium, and it makes up over 99.98% of all the hydrogen atoms.