Why do we breathe? You may say “because we need oxygen” But why do we need oxygen? Our cells need oxygen to burn fuels by cellular respiration, which is the main way cells produce the energy that they need. But why do cells in the body need energy? They need energy to do whatever type of work that they may need to do (e.g. muscle cells need energy to be able to contract). But cells also need energy to just stay alive (being alive requires plenty of energy too!). So, if cells do not get oxygen, they stop working and can die pretty quickly. The respiratory system facilitates the process of getting oxygen from the air and passing the oxygen to the blood so that the oxygen can be transported and delivered to all the cells of the body. When cells use oxygen to produce energy by cellular respiration, they generate CO2 as a byproduct. Blood will also carry CO2 from the cells to the lungs so that we get CO2 out of our body. In other words, every time that we inhale (breathe in), we take oxygen into our body and every time we exhale (breathe out), we take CO2 out of our body. . The more efficiently our lungs are able to facilitate the taking in of oxygen and the getting out of CO2, the easier it is for the body cells to keep on producing energy. When the lungs get damaged, the lungs have more difficulties getting oxygen in and CO2 out and this becomes a serious problem for the physiology of the body. . Smoking can damage the lungs and therefore reduce the efficiency of the breathing process. Another thing that smoking does is to expose the lung cells to carcinogenic chemicals from the tobacco combustion. Over time, exposing lung cells to these chemicals can lead to mutations in their DNA, which eventually can turn these cells into cancerous cells. . For this video I used a Leica ZOOM 200 stereoscope and an Olympus BX41 microscope at up to 1000x magnification #microscopy #microscope #physiology #lung #histology #lungofsmoker #alveoli #drbioforever