Biology: Lung Disease

Biology: Lung Disease

1. Tuberculosis

   • Transmission
     • Spread by droplets of water/mucous Inhaled into another person's respiratory system
   • Bacterium - Mycobacterium tuberculosis
   • Course of Infection
     • The bacteria can grow and divide in the upper regions of the lungs. Phagocytes can engulf and digest the bacteria. They can become encased in a tubercule. The bacteria can destroy the alveoli, causing fibrosis and scar tissue. The damage leads to less diffusion of gases, due to less surface area and larger diffusion pathway.  
   • Symptoms
     • Persistant cough Tiredness Loss of apetite Fever Coughing up blood

2. Pulmonary Fibrosis

   • Scarring of the epithelium of the lungs
     • Irreversibly thickened
     • Larger diffusion pathway
   • The volume of air the lungs can contain is reduced
   • Reduces the elasticity of the lungs
     • Lack of stretch and recoil
       • Air cannot be expulsed so lung ventilation is difficult
   • Symptoms
     • Shortness of breath Fatigue Chest pain Chronic cough 

3. Emphysema

   • Symptoms
     • Shortness of breath Chronic cough Fatigue 
   • Breaking down of the alveoli
     • Surface area of the lungs is reduced
     • Elastin break down
       • Lack of stretch and recoil
         • More difficult to expel air
   • Caused by smoking

4. Asthma

   • Caused by allergens
   • Also triggered by air pollution, exercise, cold air...
   • What happens:
     • Allergens cause WBCs to move to site of infection.  Release histamine Lining of airways inflammed.  Cells produce more mucus. Bronchioles contract, constricting the airways. Airways in turn become blocked 
   • Symptoms
     • Difficulty breathing Tight chest pain  Wheezing Coughing