So, before we get into the meat of the posts that I’ve planned for the month, I want to lay down a foundation of knowledge that further posts will build on. To do this, I have to discuss what asthma actually is – for many people, this will be review.
Asthma is a chronic lung condition where people have episodes (called attacks or flares) of difficulty breathing. Their breathing may or may not return to normal between these attacks, but it is always better between attacks than during attacks. In asthma, lungs are often irritated. This irritation causes swelling and redness, and in medical terms is called inflammation. The problem with lung swelling is that your lungs are a series of progressively-smaller, ever-branching tubes called airways. Air goes from your trachea, to your left and right bronchi (large airways), and from there the airways branch into smaller and smaller airways, eventually becoming the small airways, or bronchioles. When the bronchioles are so tiny that they’re microscopic, they stop at little sacs called alveoli. At the alveoli is where all your air exchange occurs, with carbon dioxide leaving your blood and oxygen entering.
In order for your lungs to work, you need to be able to get air from outside of your body all the way down to your alveoli and back again. You do this every time you breathe: Your diaphragm contracts, creating a slight vacuum in your chest cavity, which makes your lungs inflate and suck air into them. That’s inhaling. When you breathe out, called exhaling, your diaphragm just relaxes and the air flows out of your lungs passively.
Or, at least, that’s how it should happen.
In asthma, things sometimes work a bit differently. Remember when I mentioned about the inflammation? Well, the problem with swelling inside your lungs is that it blocks the airways a bit. In medical terms, this is called airway obstruction. This can make it hard to move air. As well, your airways are coated in a type of muscle called smooth muscle. If your airways get inflamed, the smooth muscle gets twitchy and sometimes can go into a spasm. This is called a bronchospasm. It’s like a muscle spasm in your hand, except when your airways spasm, it clamps your airways shut even more. So now you have obstruction because of the inflammation and more obstruction because of the bronchospasm, and this is an asthma flare or an attack. Airway obstruction makes it hard to breathe, and is the direct cause of all the asthma symptoms I’ll discuss in later posts. In asthma, airway obstruction is reversible, meaning that between attacks, your airways are not as blocked up as they are during attacks. The obstruction can be fully reversible, where people breathe normally between attacks, or only partially reversible, where people always have at least a little breathing trouble, depending on how bad a person’s asthma is.
So, the point of this post was to explain a bit about what asthma is and how it works. If I’ve done my job right, you should now know that asthma is a condition of reversible airway obstruction, the names of different types of airways, and the role of inflammation and bronchospasm in asthmatic airway obstruction. Tomorrow, I will talk about asthma symptoms.