Function of the lungs

The primary function of the lungs is to allow oxygen to transfer into the bloodstream which is essential to enable all of the cells in our body to function. As part of the process of utilising oxygen a chemical compound called carbon dioxide is created. Too much carbon dioxide in our blood can be dangerous and the lungs also help to remove this, thus ensuring the blood does not become too acidic.

Normal lung structure

In order to understand the changes that happen to the lungs in COPD it is important to understand how they are normally arranged and function.

Each person has two lungs which are located in the chest on either side of the heart. Beneath the lungs sits a muscle called the diaphragm which is important to help the lungs to fill with air. When we want to take a breath this muscle contracts and flattens causing air to rush in through a series of tubes before reaching small sac like structures located deep within the lungs. The first of these tubes is called the trachea which splits into two slightly smaller tubes called the right and left main bronchi. These continue to divide into smaller and smaller tubes known as bronchioles which end at small sacs called alveoli. It is at the alveoli were oxygen and carbon dioxide are transferred from the lungs into the blood stream and vice versa.

For a useful diagram showing this, follow this link to the British Lung Foundation website.

The lungs in COPD

In COPD the lungs become damaged resulting in changes to the bronchi, bronchioles and alveoli.

The tubes (bronchi) become inflamed and narrowed. As a result of this inflammation more mucus and sputum can be produce further clogging up these tubes. These changes are often referred to as bronchitis.

Damage also happens to the smaller sacs deep within the lungs. The walls of these sacs begin to break down resulting in larger holes forming (often referred to as emphysema). This means there is a smaller surface area for oxygen to enter into blood as well as causing air to become trapped in these spaces.

Both of these changes mean that it can be harder to move air out of and therefore bring fresh air into your lungs.

Useful links from the British Lung Foundation:

• How your lungs work
• What is COPD