Lungs and Lung Disease

Lungs and Lung Disease

1. Lung Function

   • Gross Structure Lungs
     • Bronchioles
     • Bronchi
     • Trachea
     • Lungs
     • Alveoli
       • Elastic Fibres
       • Highly Vasuclarised
       • Large surface area:volume
       • V thin wall
       • Goblet and cilliated cells
     • Produce Mucus, have rings of cartilage,(except terminal bronchioles) Cilia and elastic walls
   • Ventilation of the lungs
     • Controlled in Medulla Oblongata
     • Chemoreceptors sensitive to CO2 in the corotid arteries and the aorta
     • 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
     • Inspiration and Expiration
   • Spirometry
     • measures volume and speed of inhalation and exhalation
     • used to test for various lung diseases

2. Lung Disease

   • for Asthma Emphysemia and fibrosis you only need to know how it impacts lung function
   • Pulmonary TB
     • Symptoms
       • persistent cough w blood and phlegm
       • Night Sweats
       • High Temperature
       • Fatigue
       • Loss of appetite
     • Course of Infection
       • -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
       • Bacteria multiply @ top of the lungs w lots of oxygen
       • white blood cells respond and ingest bacteria
         • immune system builds wall around the bacteria called tubercles
         • Infected tissue within tubercles dies and gaseous exchange surface is damaged
       • inflammation of the lymph nodes that drain the lungs= primary infection
         • bacteria usually remain many years later they can re emerge = secondary infection
       • bacteria destroy lung tissue- lung repairs itself using scar tissue- person coughs up damaged lung tissue and bacteria
       • if it spreads to the rest of the body it can be fatal
     • Transmittion
       • inhaling tiny droplets from the coughs or sneezes of an infected person
       • prolonged contact e.g living with a sufferer
   • Fibrosis
     • volume of lungs occupied by fibrotic tissue
       • causes shortness of breath
     • thickness of epithelium so diffusion pathway has increased
     • lungs are less elastic= less effective ventilation
     • fibrous tissue obstructs airways
     • large mass fibrous tissue= pressure on the lungs
   • Emphysemia
     • elastin is permanently stretched
     • means lungs cannot expel air efficiently out of the lungs
       • hard to ventilate the lungs
     • surface area of the alveoli is reduced- sometimes causes them to burst
       • little- no gas exchange
   • Asthma
     • histamine causes linings of the bronchi and bronchioles to become inflamed
     • epithelial cells produce more mucus
     • muscle surrounding bronchioles contract
     • all this constricts airways greatly reducing gas exchange since ventilating the lungs becomes v difficult