Lung Diseasehow different diseases affect the lungs.WAL:

All

Most

Some

• What are fibrosis, asthma and emphysema?

• How do fibrosis, asthma and emphysema impair lung function?

• What are the risk factors for developing different lung diseases?

Today we are covering from the specification:

Pages 82 to 85 of your textbook

http://www.youtube.com/watch?v=Gh2Ovh0uAss

Pulmonary fibrosis

Recap from last lesson....1. What is pulmonary tuberculosis?2. What is it caused by?3. How is it transmitted?4. How does it affect the lungs?5. How could it be prevented?

Lung disease – fibrosis, asthma and emphysema

• Pulmonary tuberculosis is only one disease which affects the lungs.

• Fibrosis, asthma and emphysema can all also impair lung function in a number of different ways...

Pulmonary FibrosisDescriptionHappens when scars form on the pulmonary epithelium, causing them to become irreversibly thickened. This means that in patients with fibrosis, O2 cannot diffuse properly into the blood. Fibrosis also reduces the elasticity of the lungs and therefore makes ventilating the lungs difficult.

CauseThe exact cause is unclear, but evidence suggests it is a reaction to microscopic lung injury, to which some individuals are more susceptible.

Cigarette smoking can increase the risk or worsen the disease.

Pulmonary FibrosisSymptomsShortness of breath, especially when exercising due to a decrease in volume of lungs as there is an increase in scar (fibrous connective) tissue. Thickened epithelium means that diffusion pathway is greater. Loss of elasticity makes ventilation difficult. All of these factors combine to decrease the rate of diffusion.

Chronic, dry cough due to the fibrous tissue causing an obstruction. This is the body’s reflex to remove an obstruction.

Pain and discomfort in the chest occurs due to the pressure in the lungs and hence damage from the mass of fibrous tissue.

Weakness and fatigue results from reduced intake of O2.

Pulmonary Fibrosis

AsthmaDescriptionAsthma is an example of a localised allergic reaction. It affects up to 10% of the world population and accounts of 2000 deaths each year in the UK. Some of the most common allergens include pollen, animal dander, faces of house dust mites.

It can be triggered or worsened by pollutants (e.g sulphur dioxide, ozone, nitrogen oxides), exercise, cold air, anxiety or stress. These allergens cause white blood cells to release histamines in the bronchi and bronchioles, causing the following effects....

Asthma• The lining of these airways becomes inflamed.• The cells of the epithelial lining secrete larger quantities of

mucus than normal.• Fluid leaves the capillaries and enters the airways.• The muscle surrounding the bronchioles contracts and so

constricts the airways.

AsthmaCausesGenetics appears to play a role, as asthma tends to run in families. The number of asthmatics continues to rise and many explanations have been put forward for this;

• Increase in air pollution.• Increase in stress levels.• Increase in chemicals used in food and other manufactured products.• Our now ‘cleaner’ lifestyles means we are exposed to fewer allergens and therefore don’t build up a tolerance to them.

AsthmaSymptomsDifficulty in breathing due to the constriction of the bronchi and bronchioles, their inflamed linings and the additional fluid and mucus within them.

A wheezing sound when breathing caused by the air passing through very constricted bronchi and bronchioles.

A tight feeling in the chest is a consequence of not being able to ventilate the lungs adequately because of constricted bronchi and bronchioles.

Coughing is the body’s response to the obstructed bronchi and bronchioles in an attempt to clear them.

Asthma

EmphysemaDescriptionOne in every five smokers will develop emphysema. It develops over a period of around 20 years or so, and it is virtually impossible to diagnose until the lungs have been irreversibly damaged.

Healthy lungs contain large amounts of elastic tissue, mostly made up of the protein elastin. This tissue stretches when we breathe in and springs back when we breathe out.

In emphysematous lungs the elastin has become permanently stretched and the lungs are no longer able to force out all of the air from the alveoli. The surface area of the alveoli are reduced and sometimes they burst. As a result, little if any exchange of gases can take places across the surface of the stretched and damaged sacs.

EmphysemaCausesEmphysema is almost always caused by smoking tobacco. A few cases have been found to have other causes, and these will be known as secondary emphysema.

The only way at all to minimise the changes of developing emphysema is to not smoke at all.

EmphysemaSymptomsShortness in breath results from difficulty exhaling air due to loss of elasticity in the lungs. If the lungs cannot be emptied, then it is even more difficult to inhale fresh air containing oxygen and so the patient feels breathless.

Shallow, rapid breathing due to the smaller alveolar surface area resulting in a reduced intake of O2. The patient tries to increase intake of O2 by breathing more rapidly.

Chronic cough is the consequence of lung damage and the body’s effort to remove damaged tissue and mucus that cannot be removed naturally because the cilia have been destroyed.

Bluish skin colouration due to low levels of O2 in the blood.

Emphysema

Emphysema

Emphysema

Emphysema

Emphysema

Revision skills – note takingDisease name

Description Causes Symptoms (effects on lung function)

Pulmonary Fibrosis

Asthma

Emphysema

Revision skills – note takingDisease name

Description Causes Symptoms (effects on lung function)

Pulmonary Fibrosis

Asthma

Emphysema

20 minutes

You are now.... Gregory House, M.D

• You are going to diagnose a number of patients who are suffering with various lung diseases.

• You can work in groups (as House would!) but you must write up your own case notes (i.e why you have diagnosed with one disease and not another).

• The group to get the most number correct may win a prize!

You are now.... Gregory House, M.D

1. Read the patient’s case notes.2. Consider past medical history and current

symptoms.3. Come up with a diagnosis (write this down).4. Reason your decision (write this down).

30 minutes (5 minutes per patient)

You are now.... Gregory House, M.D

Patient Group 1 Group 2 Group 3 Group 4 Group 5

A

B

C

D

E

X

You are now.... Gregory House, M.D

Patient AIs suffering from....

Tuberculosis

You are now.... Gregory House, M.D

Patient BIs suffering from....

Emphysema

You are now.... Gregory House, M.D

Patient CIs suffering from....

Pulmonary fibrosis

You are now.... Gregory House, M.D

Patient DIs suffering from....

Asthma

You are now.... Gregory House, M.D

Patient EIs suffering from....

Tuberculosis

You are now.... Gregory House, M.D

Patient XIs suffering from....

Take your pick (except asthma!) but requires clear justification for a single or multiple

disease diagnosis.

Now covering from the specification:

Pages 84 & 85 of your textbook

Risk factors for lung disease

• Read pages 84 & 85• Answer questions 1 to 4 in the light greeney

blue box.(why can’t they use normal colours?!)

15 minutes

Homework – due 24/11/11

• Complete the “exam style questions” 4, 5 & 6 on page 87 of your textbook.

• Read pages 100 to 103 before next lesson.