Asthma

I’ve decided to do a post on a condition I suffer with this week, partly so I can learn more about what I actually have and partly because its going to be one of the typical things any doctor is going to meet fairly regularly. About 10% of children aged 5-12 years old have asthma with boys about twice as likely to have it than girls. Most sufferers tend to grow out of the condition however although sometimes it can get worse. There is no definite reason why some people are asthmatics and other aren’t but there is almost certainly a genetic factor. The condition also appears to be getting more prevalent in many countries for indefinite reasons; pollution being the most likely. Although my asthma is mild and fairly well managed asthma severity varies greatly from sufferer to sufferer.

 At its very simplest asthma is the muscles of the airways tightening and the lining becoming inflamed and swelling in response to an asthma trigger. Both of these cause the airway to be constricted and gas can’t travel as easily in and out leading to shortness of breath and wheezing. Common asthma triggers are exercise, animal fur, stress and pollen. It is believed (but obviously can’t be completely proven) that it is possible to make any one have asthma-like symptoms given enough time and enough chemicals. Severe asthma attacks can cause the oxygen concentration of the blood to drop significantly and gives the lips and tongue of blue colour of cyanosis. Some very extreme case when the damage caused by asthma is irreversible the condition can be included in COPD (Chronic Obstructive Pulmonary Disease), a combination of bronchitis and emphysema where the respiratory system is progressively more obstructed and eventually fatal.

 On a cellular level the inflammation caused by asthma is very complex. Various different types of white blood cells all play a role including lymphocytes, eosinophils, neutrophils, basophils and mast cells:

• ·      Eosinophils are white blood cell designed to combat multi-cellular parasites. They contain small granules inside them containing various nasty enzymes for killing the parasite. Asthma causes eosinophils to build up in the lungs (where they are normally never found) and discharge their toxin mix inappropriately. This causes the damage to the air passages seen in cases of serious asthma.

A Eosinophil cell

A Histamine molecule

• ·      Basophils are cell in the blood containing granules of histamine. Mast cells are essentially the same but live in tissues not the blood. Histamine is the chemical that triggers the inflammatory response in many allergies (in minor allergies such as hay fever the disease can effectively be managed by taking antihistamines that negate the effects of histamine but for asthma antihistamines are generally ineffective). Normally these cell release histamine when a pathogen is detected so the capillaries widen and allow white blood cell better access to the infected tissues. In asthma no real threat exists so the histamine just causes inflammation, which blocks the airways. 
• ·      Lymphocytes are the cell that recognise threats to the body and react to it. Asthma can be caused by the lymphocytes reacting to something that is not actually a threat.
• ·      Neutrophils are a type of phagocyte that normally engulfs bacteria. In asthma they contribute to the inflammation response.

Next week I’m planning to continue this post on asthma with the various treatments currently available and how they work.