Dr Adrian Harrison has been a respiratory physician at Auckland DHB since 1979 and in private since 1989.
He welcomes referrals and enquiries for patients with conditions across the respiratory spectrum and has particular interest in the areas of cough, bronchiectasis, and mycobacterial lung disease. He gives priority to the rapid investigation of lung cancer and drainage of pleural effusions. He is interested in smoking cessation and general motivation.
Areas of Interest:
- Cough (member of the Lung Foundation of Australia Cough guidelines committee)
- Endoscopy - Bronchoscopy
- Investigation of Lung Cancer
- Interstitial Lung Diseases
- Pleural Effusion
THE RESPIRATORY SYSTEM
- Centres in the brain that enable us to breathe automatically.
- The chest wall and diaphragm, which make up a bellows system. It is the regular expansion and contraction of this mechanical system that enables us to breathe.
- The lungs.
- Firstly, there are the breathing tubes that bring in fresh air (with oxygen) and take away the 'stale' air, from which some oxygen has been removed and carbon dioxide from the tissues has been added. The different levels of breathing tubes include the trachea (windpipe), the bronchi (large airways) and bronchioles (small airways). Thus, the structure of the breathing tubes is like the trunk and branches of a tree - a tree which is upside down, compared with a real tree.
- Secondly, there are the air sacs (or alveoli), that bud off the tiniest breathing tubes. The alveoli form a sponge-like tissue that makes up the main bulk of the lungs. There are very tiny blood vessels in the alveolar walls. The total surface area of the walls of the alveoli is enormous, and it is through this delicate tissue that oxygen and carbon dioxide enter and leave the blood stream, respectively.
As we breathe in, the alveoli expand and fresh air rushes down the breathing tubes. Oxygen passes through the walls of the air sacs into blood vessels, where it attaches to haemoglobin in red blood cells. Oxygen is thus transported around the body in the blood, and diffuses out to supply the various bodily tissues. The opposite happens to carbon dioxide. Carbon dioxide formed in body tissues becomes dissolved in the blood and travels to the lungs. Here, carbon dioxide diffuses out of the blood stream, passing through the walls of the air sacs into the alveolar spaces. From there it is exhaled through the breathing tubes as we breathe out.
- Cough - can be the result of problems in the upper respiratory tract, the airways, and the lung tissue (the walls of the air sacs). Additionally, the stomach and oesophagus can be implicated (gastro-oesophageal reflux).
- Sputum (also known as mucus or phlegm). Mucus is formed by special cells in the lining of the breathing tubes and the lining of the sinuses and the nose. Larger than normal amounts of mucus are usually the result of inflammation or infection in these tissues. Most antibiotics are useless if the mucus is clear in colour (there is one exception, though).
- Breathlessness - can originate from one or more sites. The signal causing breathlessness may come from the brain, the airways, lung tissue (air sacs), the pleural space and the chest wall. The heart is another place where breathlessness can originate. Interestingly, lack of oxygen does not cause breathlessness.
- Chest pain - a practical anatomical point is that the pleura and breathing tubes have pain-sensitive nerve fibres - but the lungs do not. Chest pain can come from the chest wall (with its muscles, ligaments, ribs and nerves), the trachea and bronchi, the pleura, the heart and the oesophagus (gullet) - but not from the lung tissue (the air sacs or alveoli).
- Coughing blood - blood can come from the upper respiratory tract (including the mouth), the breathing tubes and from lung tissue. Infection, inflammation or tumour can cause bleeding from any of these areas. (Trauma to them can cause bleeding - but you already know that!)