Lungs and Lung Disease

1. Gross Structure Lungs
   1. Bronchioles
   2. Bronchi
   3. Trachea
   4. Lungs
   5. Alveoli
      1. Elastic Fibres
      2. Highly Vasuclarised
      3. Large surface area:volume
      4. V thin wall
      5. Goblet and cilliated cells
   6. Produce Mucus, have rings of cartilage,(except terminal bronchioles) Cilia and elastic walls
2. Ventilation of the lungs
   1. Controlled in Medulla Oblongata
   2. Chemoreceptors sensitive to CO2 in the corotid arteries and the aorta
   3. Impulses sent from chemoreceptors to medulla, then from the medulla to the diaphragm via the phrenic nerve, this controls the rate and strength of contraction of the diaphragm
   4. Inspiration and Expiration
3. Spirometry
   1. measures volume and speed of inhalation and exhalation
   2. used to test for various lung diseases

Annotations:

• for Asthma Emphysemia and fibrosis you only need to know how it impacts lung function

1. Pulmonary TB
   1. Symptoms
      1. persistent cough w blood and phlegm
      2. Night Sweats
      3. High Temperature
      4. Fatigue
      5. Loss of appetite
   2. Course of Infection

      Annotations:

      • -EXAM MARK SCHEME- -spread via droplet transmission -bacteria are ingested via phagocytosis in the lungs -encased in a wall by immune system cells which is called a tubercle -bacteria remain dormant within tubercles  -if the person is immuno-supressed the bacteria can become activated  -they then destroy lung tissue and alveoli -this leads to fibrosis/ cavities -less surface area for gas exchange in the lungs -this activation allows bacteria to enter the blood stream and affect other organs
      1. Bacteria multiply @ top of the lungs w lots of oxygen
      2. white blood cells respond and ingest bacteria
         1. immune system builds wall around the bacteria called tubercles
         2. Infected tissue within tubercles dies and gaseous exchange surface is damaged
      3. inflammation of the lymph nodes that drain the lungs= primary infection
         1. bacteria usually remain many years later they can re emerge = secondary infection
      4. bacteria destroy lung tissue- lung repairs itself using scar tissue- person coughs up damaged lung tissue and bacteria
      5. if it spreads to the rest of the body it can be fatal
   3. Transmittion
      1. inhaling tiny droplets from the coughs or sneezes of an infected person
      2. prolonged contact e.g living with a sufferer
2. Fibrosis
   1. volume of lungs occupied by fibrotic tissue

      Annotations:

      • causes shortness of breath
   2. thickness of epithelium so diffusion pathway has increased
   3. lungs are less elastic= less effective ventilation
   4. fibrous tissue obstructs airways
   5. large mass fibrous tissue= pressure on the lungs
3. Emphysemia
   1. elastin is permanently stretched
   2. means lungs cannot expel air efficiently out of the lungs
      1. hard to ventilate the lungs
   3. surface area of the alveoli is reduced- sometimes causes them to burst
      1. little- no gas exchange
4. Asthma
   1. histamine causes linings of the bronchi and bronchioles to become inflamed
   2. epithelial cells produce more mucus
   3. muscle surrounding bronchioles contract
   4. all this constricts airways greatly reducing gas exchange since ventilating the lungs becomes v difficult