What is lungs and how does it works ?
Lung cancer affects a life-sustaining system of the body, the respiratory system. The respiratory system is responsible for one of the essential functions of life, breathing. Breathing enables us to take in oxygen and expel carbon dioxide. Every cell in the body depends on oxygen to function. If the supply of oxygen is impaired in any way, the entire body is affected. An understanding of how the lungs and respiratory system work will help you understand how lung cancer affects the body. It may also be helpful as you talk with your health care providers, gather information about your illness, and communicate with your family and friends
How do the lungs normally work?
The chest contains two lungs, one lung on the right side of the chest, the other on the left side of the chest. Each lung is made up of sections called lobes. The lungs are soft and protected by the ribcage. The purpose of the lungs is to bring oxygen into the body and to remove carbon dioxide. Oxygen is a gas that provides us with energy, while carbon dioxide is a waste product or “exhaust” of the body.
How does air get into the body?
To deliver oxygen to the body, air is breathed in through the nose, mouth or both. The nose is the preferred route, since it is a better filter than the mouth. The nose decreases the amount of irritants delivered to the lungs, whilst also heating and adding moisture (humidity) into the air we breathe. When large amounts of air are needed, the nose is not the most efficient way of getting air into the lungs and therefore mouth breathing may be used. Mouth breathing is commonly needed when exercising. After entering the nose or mouth, air travels down the trachea or “windpipe”. The trachea is the tube lying closest to the neck. Behind the trachea is the oesophagus or “food tube”. When we inhale, air moves down the trachea, and, when we eat, food moves down the oesophagus. The path air and food take is controlled by the epiglottis, a gate that prevents food from entering the trachea. Occasionally, food or liquid may enter the trachea, resulting in choking and coughing spasms. The trachea divides into one left and one right breathing tube, and these are termed bronchi. The left bronchus leads to the left lung and the right bronchus leads to the right lung. These breathing tubes continue to divide into smaller and smaller tubes called bronchioles. The bronchioles end in tiny air sacs called other set is responsible for transporting oxygen from the lungs to the body via the heart. Blood that has picked up oxygen from the lungs returns to the left side of the heart and is pumped out to deliver this oxygen-rich blood (called arterial blood) to the body. After the blood has delivered oxygen to the cells of the body (skin, organs, etc.) it is called venous blood, which returns to the right side of the heart. Venous blood contains high amounts of carbon dioxide and small amounts of oxygen. The venous blood returns to the lungs to get rid of carbon dioxide and to pick up oxygen.
The respiratory system has one vital function, breathing. When you breathe in or inhale, your body receives oxygen. Oxygen is a gas in the air that is needed to sustain life. The human body cannot survive without oxygen for more than a few minutes. When you breathe out or exhale, you rid the body of carbon dioxide, a gas produced by normal body functions. Getting rid of carbon dioxide is necessary because excessive amounts of carbon dioxide are toxic. The lungs are the place in the body where essential oxygen is taken in, and toxic carbon dioxide is released. When the lungs have difficulty doing their job, other organs in the body have difficulty doing their jobs. Therefore, the health of the lungs has direct and immediate effects on the overall health of the body.
What about oxygen and carbon dioxide?
Surrounding each alveoli are tiny blood vessels or capillaries. The tiny blood vessels surround the alveoli like a net. This is where the oxygen that has travelled down the breathing tubes into the alveoli enters the blood. The carbon dioxide or “exhaust” gas from the body trades places with the oxygen by leaving the blood and entering the alveoli. Carbon dioxide is then exhaled out of the lungs. For our body to function well, oxygen must enter the blood and carbon dioxide must leave the blood at a regular rate. The lungs also contain blood vessels and a covering of nerve fibres. Outside of the lungs, there are two layers of thin material called pleura. One pleura is attached directly to the outside of the lungs and the other is attached to the inside of the chest, close to the ribs. The lungs also have two sets of blood vessels. Blood vessels can be arteries or veins. One set of blood vessels feeds into and nourishes the lungs, whilst the pollutants from entering the lungs. If an irritant does enter the lungs, it will get stuck in a thin layer of mucus (also called sputum or phlegm) that lines the inside of the breathing tubes. An average of 70 grams of mucus is secreted onto the lining of these breathing tubes every day. This mucus is “swept up” toward the mouth by little hairs called cilia that line the breathing tubes. Cilia move mucus from the lungs upward toward the throat to the epiglottis. The epiglottis is the gate that opens allowing the mucus to be swallowed. This occurs without us even thinking about it. Spitting up sputum is not “normal” and does not occur unless the individual has chronic bronchitis or there is an infection, such as a chest cold, pneumonia or an exacerbation of chronic obstructive pulmonary disease (COPD). Another protective mechanism for the lungs is the cough. A cough, while a common event, is also not a normal event and is the result of irritation to the bronchial tubes. A cough can expel mucus from the lungs faster than cilia. The last of the common methods used by the lungs to protect themselves can also create problems. The airways in the lungs are surrounded by bands of muscle. When the lungs are irritated, these muscle bands can tighten, making the breathing tube narrower as the lungs try to keep the irritant out. The rapid tightening of these muscles is called bronchospasm. Some lungs are very sensitive to irritants. Bronchospams may cause serious problems for people with COPD and they are often a major problem for those with asthma, because it is more difficult to breathe through narrowed airways.