A4. The Effects of Lung Disease Flashcards
Lung function
Tidal volume is … - usually between … for adults.
Ventilation rate … For a healthy person at rest it’s about __ breaths.
Forced expiratory volume (FEV) is …
Forced vital capacity (FVC) is …
Tidal volume is the volume of air in each breath - usually between 0.4 dm’ and 0.5 dm³ for adults.
Ventilation rate is the number of breaths per minute. For a healthy person at rest it’s about 15 breaths.
Forced expiratory volume (FEV) is the maximum volume of air that can be breathed out in 1 second.
Forced vital capacity (FVC) is the maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in.
Tip: dm³ stands for decimetres cubed. 1 dm³ is the same as…
Tip: dm³ stands for decimetres cubed. 1 dm³ is the same as 1 litre of 1000 cm³.
Lung diseases - Tuberculosis
How is it caused?
What happens and what is its effect?
What does it also cause and what does this do?
What does the effect mean?
What do patients have to do in consequence to this?
What are the common symptoms?
- caused by bacteria - when someone becomes infected with tuberculosis bacteria, immune system cells build a wall around the bacteria in the lungs.
- Infected tissue within the tubercles dies and the gaseous exchange surface is damaged, so tidal volume is decreased.
- TB also causes fibrosis which further reduces the tidal volume.
- A reduced tidal volume means less air can be inhaled with each breath.
- In order to take in enough oxygen, patients have to breathe faster, i.e. ventilation rate is increased.
- Common symptoms include a persistent cough, coughing up blood and mucus, chest pains, shortness of breath and fatigue.
Lung diseases - Fibrosis
What is it and how is it caused?
What happens and what is its effect?
What also happens and what does this do?
What do patients have to do in consequence to this?
What are the common symptoms?
- 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 lung tissue.
- This means that the lungs are less able to expand and so can’t hold as much air as normal tidal volume is reduced, and so is FVC
- There’s a reduction in the rate of gaseous exchange - 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.
- Symptoms of fibrosis include shortness of breath, a dry cough, chest pain, fatigue and weakness.
Lung diseases - Asthma
What happens?
Cause?
What happens in an asthma attack?
What does it cause?
Symptoms?
- Asthma is a respiratory condition where the airways become inflamed and irritated.
- The causes is usually because of an allergic reaction to substances such as pollen and dust.
- 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 and moves into the blood. Reduced air flow means that FEV, is severely reduced
- Symptoms include wheezing, a tight chest and shortness of breath. During an attack the symptoms come on very suddenly.
Lung diseases - Emphysema
What is it and how is it caused?
What does it casue?
What happens and what is its effect?
Symptoms?
- Emphysema is a lung disease caused by smoking or long-term exposure to air pollution
- This causes inflammation, which attracts phagocytes to the area. The phagocytes produce an enzyme that breaks down elastin
- Loss of elastin means the alveoli can’t recoil to expel air as well (it remains trapped in the alveoli). It also leads to destruction of the alveoli walls, which reduces the surface area of the alveoli so the rate of gaseous exchange decreases.
- Symptoms of emphysema include shortness of breath and wheezing. People with emphysema have an increased ventilation rate as they try to increase the amount of air (containing oxygen) reaching their lungs.
The effect of lung diseases on gas exchange
TB, fibrosis, asthma and emphysema all …(3 steps)
1) Reduce the rate of gas exchange in the alveoli.
2) Less oxygen is able to diffuse into the bloodstream, the body cells receive less oxygen and the rate of aerobic respiration is reduced.
3) This means less energy is released and sufferers often feel tired and weak.
Interpreting graphs - Example 1
Describe and explain?
Tip: If the graph included a line for someone with a restrictive disease, like fibrosis, FVC would be ….because …. FEV is likely to be relatively ____compared to FVC because someone with a restrictive disease is able to ….
Tip: If the graph included a line for someone with a restrictive disease, like fibrosis, FVC would be severely reduced because it’s hard to get air into the lungs. FEV is likely to be relatively high compared to FVC because someone with a restrictive disease is able to breathe out fairly normally.
Interpreting graphs - Example 2
