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.
This unit is actually not the mass of a proton or neutron in grams but is a mass ratio based on the element carbon. An amu is defined as 1/12 of the mass of a carbon atom. Proton...Protons have a positive charge. The number of protons in a nucleus determines the identity of the atom (element) and this number is called the atomic number. The actual mass of a proton has been determined to be 1.673 x 10-24 gram. Scientists use the metric system of measurement where the standard unit for mass is the gram.