The Effects of Lung Disease Flashcards
What does lung disease affect?
Lung disease affects both ventilation and gas exchange in the lungs
What is tidal volume?
Tidal volume is the volume of air in each breath - usually between 0.4 dm3 and 0.5 dm3 for adults
What is the ventilation rate?
Ventilation rate is the number of breaths per minute. For a healthy person this is around 15 breaths
What is the forced expiratory volume 1 (FEV1)?
Forced expiratory volume 1 is the maximum volume of air that can be breathed out in 1 second
What is forced vital capacity (FVC)?
Forced vital capacity is the maximum volume of air it is possible to breath forcefully out of the lungs after a really deep breath in
Give four examples of different lung diseases
- Pulmonary tuberculosis (TB)
- Fibrosis
- Asthma
- Emphysema
How does tuberculosis affect the lungs?
When somebody becomes infected with tuberculosis bacteria, immune system cells build a wall around bacteria in the lungs. This forms small, hard lumps known as tubercles. Infected tissue within the tubercles dies and the gaseous exchange surface is damaged, so tidal volume decreases. TB also causes fibrosis, which further reduces tidal volume. A reduced tidal volume means less air can be inhaled with each breath so patients have to breath faster, increasing ventilation rate
What are the common symptoms of pulmonary tuberculosis?
A persistent cough, coughing up blood and mucus, chest pains, shortness of breath and fatigue
How does fibrosis affect the lungs?
Fibrosis is the formation of scar tissue in the lungs. This can be the result of an infection or exposure to substances like asbestos or dust. Scar tissue is thicker and less elastic than normal tissue - the lungs are less able to expand and so can’t hold as much air as normal - tidal volume is decreased and so is FVC. There’s a reduction in the rate of gaseous exchange because diffusion is slower across a thicker scarred membrane. Fibrosis sufferers have a faster ventilation rate than normal - to get enough air into their lungs to oxygenate their blood
What are the common symptoms of fibrosis?
Shortness of breath, a dry cough, chest pain, fatigue and weakness
What is asthma?
Asthma is a respiratory condition where the airways become inflamed and irritated. The causes vary from case to case but it’s usually because of an allergic reaction to substances such as pollen or dust
How does asthma affect the lungs?
During an asthma attack, the smooth muscle lining the bronchioles contracts and a large amount of mucus is produced. This causes constriction of the airways, making it difficult for the sufferer to breathe properly. Air flow in and out of the lungs is severely reduced, so less oxygen enters the alveoli in moves into the blood. Reduced air flow means FEV1 is severely reduced
What are the common symptoms of asthma?
Wheezing, a tight chest and shortness of breath. During an attack the symptoms come on very suddenly. They can be relieved by drugs (often in inhalers) which cause the muscles in the bronchioles to relax, opening the airways
What is emphysema?
Emphysema is a lung disease caused by smoking or long-term exposure to air pollution
How does emphysema affect the lungs?
Foreign particles in the smoke (or air) become trapped in the alveoli. This causes inflammation, which attracts phagocytes to the area. The phagocytes produce an enzyme that breaks down elastin. Elastin is elastic - it helps the alveoli to return to their normal shape after inhaling and exhaling air. Loss of elastin means alveoli can’t recoil and expel air as well. It also leads to the destruction of the alveoli walls, which reduces the surface area of the alveoli, so the rate of gaseous exchange decreases. People with emphysema have an increased ventilation rate as they try to increase the amount of air (containing oxygen) to their lungs
