The human respiratory system is very similar, if not practically identical, to the respiratory system of a rat. The only notable difference is the division of the lobes in human lungs. The left lung of a rat is composed of 1 lobe, while the right lung has 4 lobes. The right lung of a human contains 3 lobes and the left lung is composed of 2 lobes. Other than that (and some structural differences along with size) the human and rat respiratory systems work in the same way. (Rat Health Guide, 2012). A respiratory disease that humans (not rats) are known to obtain is lung cancer.
To understand what lung cancer does, you must first understand how normal a human respiratory system should work. The human body contains two lungs that are soft, made up of lobes, and protected by bones known as the rib cage. The lungs bring oxygen into the body and remove carbon dioxide from it. When a human breathes, air travels down the trachea and separates into either of the bronchi and continues into the lungs. In order to keep irritants out of the lungs, the nose acts as a filter to prevent large particles from entering.
(American Thoracic Society) That is how normal lungs should work. Lung cancer is a very common, highly preventable, form of cancer. Lung cancer, like any cancer, is the uncontrolled division of cells. When lung cells divide abnormally, they can create two types of tumors. Benign tumors are not cancerous and are rarely serious. The other types of tumor, malignant tumors, are cancerous. (Ohio State University). Lung cancer may start in parts of the lungs like the bronchioles, alveoli, and the cells lining the bronchi.
(American Cancer Society, 2013). Cancer cells can spread to, and destroy, healthy cells nearby. Cells in the lungs that are cancerous can spread to the lymph glands located nearby and to other parts of the body. Approximately 95% of people diagnosed with lung cancer each year die from it. 87% of lung cancers are due to smoking tobacco. (Ohio State University) When people smoke, they not only ingest tobacco, but many other toxic poisons including carcinogens. Carcinogens have the ability to damage and alter the DNA of cells in the body.
When smoking, lung cells are exposed to these harmful substances and it can cause the uncontrollable division of cells (cancer). (eHow Health) There are two main types of lung cancers. These types are known as small cell lung cancer and non-small cell lung cancer. (Cornell University, 2013) Cancer cells of each type are treated differently, as they grow and spread in different ways. Small cell lung cancer is also known as oat cell carcinoma and accounts for about 15% of lung cancers. Oat cell carcinoma usually begins in the bronchi, but spreads quickly and early to the brain.
Small cell lung cancer responds to chemotherapy at first, but it becomes more and more defiant to treatment as the disease goes on. It is separated into two groups, extensive stage and limited stage. People are usually already at the extensive stage of the disease when they are first diagnosed. Most cases are found in men (probably because of a hormone reaction) and are due to smoking. (About. com, 2012) Non-small cell lung cancer accounts for approximately 85-90% of lung cancer. Non-small cell lung cancer (NSCLC) is divided into three different groups.
While these cancer cells vary in shape, size, and chemical-makeup, they are all grouped into NSCLC because of similar treatment and outlook. (American Cancer Society, 2013) The first sub-type of NSCLC is Adenocarcinoma. This variation of cancer accounts for 40% of all lung cancers. Adenocarcinoma tends to show up in current/former smokers; however, it is the most common lung cancer non-smokers have. It occurs in early cells that secrete mucus and is found in the outer parts of the lung. Adenocarcinoma is usually found before it spreads because it tends to grow slower.
People with this form of lung cancer usually have a better out-look than others. (American Cancer Society, 2013) The second sub-type is Squamos cell carcinoma. 25-30% of all lung cancers are squamos cell carcinoma. This type of cancer starts in the squamos cells (flat cells that line the inside of airways in the lungs) and is usually found near a bronchus. It’s linked to a history of smoking. (American Cancer Society, 2013) The final sub-type of NSCLC is large cell carcinoma. This sub-type accounts for 10-15% of lung cancers.
It is very difficult to treat because grows and spreads very quickly. It also can appear in any part of the lung. (American Cancer Society, 2013) Lung cancer is very common but also very preventable. Those who smoke are at a much greater risk to acquire lung cancer than those who don’t. Even second hand smoke increases the chance of getting lung cancer. Some lung cancers can be treated if found early enough, however, some are almost impossible to find until there is little hope for treatment. Lung cancer is a very deadly form of cancer and is usually self-inflicted.