THE LUNGS AND RESPIRATORY SYSTEM

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.

THE RESPIRATORY SYSTEM

Breathing

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.

The respiratory system is made of up of those body parts that help us take in air and expel carbon dioxide. Take a breath in and you will quickly become aware of some of the body parts of the respiratory system. Air comes in through either the nose or the mouth. It passes to the throat (pharynx), and is pulled into the windpipe (trachea). The trachea splits in two between the lungs sending one branch to each lung (see Figure 1). These branches are called the right and left main bronchus. Before we discuss the path of air once it enters the lungs, let us first consider how we manage the act of breathing.

Figure 1: The Respiratory System

Air moves in and out of the body by the action of muscles. The diaphragm is a large muscle that sits below the lungs. It separates the lungs and other organs in the chest from the organs of the abdomen. When the diaphragm contracts or tenses, it moves down causing the lungs to expand and pull in air. When the diaphragm relaxes, it moves up, pushing against the lungs and causing them to expel air. There are also muscles between the ribs that help in this cycle of expanding and contracting the lungs, forcing air in and out. Put your hands on your chest and take a breath in. You will feel your chest expand. As you breathe out, you will feel your chest move inward. This movement is the result of the diaphragm and other muscles of the chest automatically contracting and relaxing with each breath in and out.

 The lungs take up most of the space in the chest cavity, which extends from the collarbones to the diaphragm (see Figure 2). The organs of the chest are protected by the ribs. The area between the lungs in the middle of the chest is called the mediastinum. It contains the heart, windpipe (trachea), food pipe (esophagus), blood vessels, and many lymph nodes. Examination of the lymph nodes in the mediastinum is an important part of the lung cancer staging process