The effects of lung disease Flashcards
What harm would lung diseases cause?
Affect ventilation (breathing) and gas exchange.
How can lung function be measured?
- Tidal volume - the volume of air in each breath.
- Ventilation rate - the number of breaths per minute.
- Forced expiratory volume (FEV1) - the maximum volume of air that can be breathed out in 1 second.
- Forced vital capacity (FVC) - the maximum volume of air it is possible to breathe forcefully out of the lungs after a deep breath in.
What is TB?
Tuberculosis - a lung disease caused by bacteria. When someone becomes infected with TB, immune system cells build a wall around the bacteria in the lungs which form small and hard lumps known as tubercles.
Infected tissues within the tubercles die and the gaseous exchange surface is damaged so tidal volume decreases.
TB can also cause fibrosis, which further decreases the tidal volume.
Reduction of tidal volume means less air can be breathed in at each breath.
Patients will have to breath faster, common symptoms include, cough, coughing with blood and mucus, chest pains, shortness of breath and fatigue.
What is fibrosis?
Formation of scar tissue in the lungs which can lead to infection and exposure to substances like dust.
Scar tissue is thicker and less elastic than normal tissue so the lungs would expand less and can’t hold as much air as normal and tidal volume is reduced.
Gaseous exchange rate reduces as the diffusion rate is slow across a thicker scarred membrane.
Patients have a faster ventilation rate than normal so they can get enough oxygenated air into the blood.
Symptoms - shortness of breath, dry cough, chest pain, fatigue, and weakness.
What is asthma?
It’s a respiratory condition where the airways become inflamed and irritated. It’s usually triggered by an allergic reaction e.g. pollen and dust.
During an asthma attack, the muscle lining of the bronchioles contract which produces a large amount of mucus which causes blockage to the airways making it difficult for the patient to breath properly.
Less air flow in and out of the lungs so less oxygen enters the alveoli and moves into the blood, reduction in airflow means FEV1 is reduced.
Symptoms - shortness of breath
It can be relived by inhalers which causes the muscles in the bronchioles to relax and open up the airways.
What is emphysema?
A lung disease caused by smoking or long term exposure to air pollution - foreign particles in the smoke become trapped in the alveoli which causes inflammation and attracts phagocytes to the area.
The phagocytes produce an enzyme which breaks down the elastin (a protein in the walls of the alveoli). This protein provides the elasticity in the alveoli which helps it to return to their normal shape after inhaling and exhaling. Loss of elastin means that alveoli can’t breathe out the air as well so it remains trapped in the alveoli. Which leads to the destruction of the alveoli walls and reduces its SA and gas exchange rate decreases.
Symptoms - shortness of breath. Increase of ventilation rate as they try to increase the amount of air containing oxygen reaching their lungs.
What is the effect of lung disease?
Reduces gas exchange in the alveoli. Less oxygen can diffuse into the bloodstream so body cells receive less oxygen and rate of aerobic respiration is reduced so less energy is released and sufferers can often fell tired.
