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.
The mass of a proton is approximately 1.6726 * 10^-24 g. Because the masses of particles in atoms are so small, scientists developed a new unit for them. The SI unit known as the atomic mass unit, abbreviated amu, is used to express the masses of subatomic particles. Scientists assign each proton a mass of 1 amu and symbol 'p.' All protons are identical, no matter from which kind of element they come. All the atoms of one element have the same number of protons.