Lung Diseases

Lung diseases are caused by lifestyle factors and genetic factors.

Shown here: pulmonary fibrosis, asthma and emphysema


Pulmonary Fibrosis

Where scars form on the epithelium of the lungs. (exact cause is unclear but there may be a relation   to microscopic lung injury e.g. dust inhilation by minors)

Effect on lungs:

Shortness of breath - some air spaces get occupied by fibrous tissue -> less oxygen taken in at each        breath

     - thickened epithelium of alveoli diffusion pathway so diffusion of oxygen is very        slow 

     - loss of elasticity in alveoli; harder to ventilate lungs so harder to mantain a        diffusion gradient (cannot collapse fully to expel air, breathing very shallow)

Chronic dry cough - fibrous tissue is an obstruction. Reflex reaction is to try to remove it but nothing is     expelled (fibrous tissue means there's a longer diffusion pathway)

Chest pain - from the pressure and damage cause by the fibrous tissue and by the coughing

Weakness and fatigue - reduced intake of oxygen for respiration therefore release of energy from    respiration is reduced

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A localised allergic reaction; typically from pollen, animal fur or dust, made worse by pollutants and exercise, anxiety/stress. 

Allergens cause white blood cells in bronchi and bronchioles to release histamine causing airways to become inflames and more mucus to be produced by epithelial cells. Fluid leaves capillaries and enters the airways, hence greater resistance to air flow in and out. 


Difficulty breathing - bronchi and bronchioles are constricted and filled with mucus

     - diameter of airways is reduced

     - mucus creates a longer diffusion pathway so less oxygen can diffuse in

Wheezing sound when breathing - caused by air passing through the constricted bronchi and  bronchioles 

Tight feeling in chest - as not able to ventilate lungs properly

Coughing - reflex response to try to clear obstructed bronchi and bronchioles of mucus

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1 in 5 smokers develop this. The protein elastin (allows alveoli to stretch and recoil) becomes permanently stretched; some alveoli burst (fewer alveoli) therefore reducing surface area for diffusion of oxygen in.


Shortness of breath - difficult to exhale air due to loss of elastisity and difficult to inhale air as alveoli        cannot be emptied

     - smaller surface area of alveoli; reduced oxygen levels in the blood; patient tries        to increase oxygen by breathing more rapidly

Chronic cough - consequence of lung damage and body's effort to remove damaged tissue (burst        alveoli) 

     - smoking destroys the cilia on the bronchi and bronchioles so mucus cannot be wafted        away

Bluish skin colour - due to low levels of oxygen in the blood

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Risk Factors for COPD


Main risk factors:

- Smoking (over 90% of sufferers)

- Air pollution

- Genetic makeup 

- Infections

- Occupation

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