Understanding Your Lungs

The respiratory system is the network of organs and tissues that help you to breathe. Found within the thorax, the space between your neck and abdomen, the respiratory system includes airways, lungs, blood vessels and muscles. These parts work together to move oxygen throughout the body and clean out carbon dioxide, a waste gas.

The airways

Your body uses several channels that allow oxygen-rich air to enter the lungs and carbon dioxide to exit the body:

• Nasal cavities 
• Mouth
• Voice box (larynx)
• Windpipe (trachea)
• Bronchial tubes

The lungs

Your lungs are located on either side of your sternum in your thorax. They are divided into five main sections (lobes). The right lung has three lobes, and the left lung has two lobes. The heart is nestled between your lungs. The heart and lungs are protected by your rib cage.

The muscles that help you breathe

• The diaphragm: The diaphragm is the primary muscle of breathing. It is located below your lungs. It separates the chest cavity and the abdominal cavity. When the diaphragm contracts, it flattens downwards to increase the size of the chest cavity, giving more room for the lungs to expand. When this happens, air is drawn into the lungs. When the diaphragm relaxes, it curves upwards making a smaller space in the chest cavity, pushing air out of the lungs. 
• Intercostal muscles: There are different types of intercostal muscles. Some are located on the outer edges of the ribs, and others located closer to the sternum. These muscles help to expand and contract the thorax.
• Muscles of the neck and chest (Scalene and sternocleidomastoid): These muscle groups help to raise the rib cage as it draws up on the collar bone and first two sets of ribs when you inhale. They provide additional support when the lungs are not working efficiently or when there are other problems in the chest that compromise breathing.
• Abdominal muscles: These muscles are accessory, or helper, muscles. They help to move the diaphragm and give you more power to empty your lungs when you exhale.

What happens in your lungs when you breathe?

When you take a breath through your nose or mouth, this air becomes warmer and more moist. The air moves through your voice box (larynx) and down your windpipe (trachea). From there, it travels down bronchial tubes that enter the lungs. 

At the smallest end of the bronchial tubes (bronchioles) are alveoli — millions of tiny air sacs that are each covered by thin blood vessels called capillaries. The junction of alveoli and capillaries is called alveo-capillary bed. This is where gas exchange (oxygen and carbon dioxide) occurs. 

When we inhale, air reaches the alveo-capillary bed. Oxygen is transferred from inhaled air to the blood for circulation and carbon dioxide is transferred from the blood to alveoli where it is ready to be exhaled. When you breathe out, air with carbon dioxide leaves your lungs through your bronchial tubes, up through the trachea and larynx and out through your mouth or nose. 

The heart and lungs work in harmony in this process to circulate oxygen to muscles, vital organs and all cells so that they can properly function.

Lung disease can be a result of genetic conditions, environmental exposure, behaviours (such as smoking) and/or recurrent lung infections. To get the most out of every day, it is important for you to understand your lung disease. This will help you to communicate better with your healthcare provider, take charge of your symptoms and be more active in managing your disease. 

There are two main categories of chronic lung disease are obstructive lung disease and restrictive lung disease. Shortness of breath is common to both categories. A lung function test is the best way to determine determine your lung disease.

Obstructive lung disease

This category of lung disease includes chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis and cystic fibrosis. The most common diagnosis in this category is COPD, which includes emphysema and chronic bronchitis.

Obstructive lung diseases is marked by airway obstruction. This occurs when inflammation (swelling) narrows or blocks the airways. Obstruction can also occur because of extra mucus production. These conditions make it difficult to exhale the air from the lungs. When air becomes trapped, the lungs become hyperinflated and have an increased total lung capacity. This leads to poor gas exchange in the alveoli, and results in worsening shortness of breath.

Restrictive lung disease

Restrictive lung diseases are a group of lung tissue diseases that cause a reduced total lung capacity. Restrictive lung diseases can come from conditions within the lung (intrinsic), from conditions outside of the lung (extrinsic) or from neurological (nerve) or autoimmune conditions. For our purposes we will only discuss a grouping of intrinsic restrictive lung diseases known as interstitial lung disease (ILD). There are over 200 types of ILD, including sarcoidosis, asbestosis, silicosis, pneumonitis and pulmonary fibrosis. 

Most people with restrictive lung disease have a form of ILD that causes scarring or fibrosis in the lungs. Fibrosis causes thickening and stiffness in the alveoli, making it difficult to inhale. This causes poor gas exchange, which leads to increased shortness of breath and rapid breathing. A dry, hacking cough is also common for people who have ILD.