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.
According to HowStuffWorks, an atomic mass unit is defined as the mass of a single proton or neutron. Hydrogen, the lightest element, has an average mass of 1.00794 amu. A carbon-12 atom is made up of six protons and six neutrons, hence 12 atomic mass units. The mass of the electron is considered negligible, therefore electrons are not counted in measuring an atom's atomic mass.