4.4 and 4.5 - Tuberculosis, Fibrosis, Asthma and Emphysema Flashcards
(25 cards)
what are the two bacteria that cause tuberculosis?
mycobacterium tuberculosis and mycobacterium bovis
What are the SYMPTOMS of TB?
- persistent cough
- tiredness
- loss of appetite
- weight loss
- fever
- coughing up blood
How is TB spread?
Transmission in the air by droplets: coughing, sneezing, laughing or talking. M. tuberculosis can survive up to two weeks on surfaces. Usually takes long term exposure to become infected. TB can be spread from cows to humans with the m. bovis strain.
Which 4 groups of people have an increased risk of catching TB?
- those in contact with infected individuals over a long period of time
- work or reside in places where lots of people are very close together
- from countries where TB is common
- has reduced immunity
Which 7 groups have reduced immunity to TB?
1) the very young or old
2) those with AIDS
3) people with underlying medical conditions
4) those undergoing treatment with immunosupressants
5) the malnourished
6) alcoholics or injecting drug users
7) the homeless
Describe the course of infection for TB.
1) the bacteria enters and grows in the upper regions of the lungs where there is lots of oxygen
2) the body’s immune system responds and white blood cells accumulate at the area
3) this causes inflammation and swells up the lymph nodes, this is called the primary infection
4) In a healthy person there are few symptoms and it is usually fought off. Some bacteria usually remain
5) These bacteria a few years later can re-emerge to cause post-primary tuberculosis
6) This is not as easily controlled and the bacterium attacks the lung tissue, making scar tissue
7) The sufferer will cough up sputum, blood and damaged tissue with bacteria and the TB can be fatal if it is allowed to spread
What is fibrosis?
A disease which arises when scar tissue forms on the lungs causing them to become irreversibly thickened
How does fibrosis affect diffusion?
Because the lung tissue has been thickened, the diffusion pathway is made much longer and the volume the lungs can hold has been reduced. This means less oxygen diffuses across
How does fibrosis affect lung elasticity?
Because of the scar tissue, the lungs are less elastic. This means the tissue can not spring into place to push out the air in normal resting breathing.
How does fibrosis cause a DRY COUGH?
The scar tissue causes an obstruction in the lungs. The body’s reflex is to try and remove the obstruction by coughing. The tissue is immovable and therefore nothing is expelled.
How does fibrosis cause a PAIN IN THE CHEST?
The pressure and damage caused by the scar tissue and excess dry coughing causes pain
How does fibrosis cause WEAKNESS AND FATIGUE?
the lack of intake of oxygen from the lungs due to scarred tissue results in lack of cellular respiration
How does fibrosis cause a SHORTNESS OF BREATH?
A large amount of airspace is being taken up by scarred tissue so less air can be taken up. The loss of elasticity makes it difficult to ventilate the lungs and the thick pathway means diffusion is slow.
What is ASTHMA?
A local allergic reaction in the airways and lungs. It can be triggered by exercise, stress, pollen, cold air, animal fur and pollutants
How is an ASTHMA ATTACK triggered?
- The allergen causes the white blood cells on the bronchi to release histamine so
- the lining of the airway becomes inflamed
- the cells of the epithelial lining secrete more mucus than usual
- fluid leaves the capillaries and enters the airways
- the muscle around the bronchioles contracts and so constricts the airways
How does asthma cause a DIFFICULTY IN BREATHING?
Due to the constriction of the bronchi, inflamed linings and additional fluid within
How does asthma cause a WHEEZING SOUND?
Caused by air passing through the constricted bronchi
How does asthma cause a TIGHTNESS IN THE CHEST?
A consequence of not being able to ventilate the lungs properly
How does asthma cause COUGHING?
a reflex action in response to the obstructed bronchi and not being able to clear them
What is emphysema?
Where the lungs no longer contain elastin protein. This happens over a long period of about 20 years through smoking and is only diagnosable once the lungs have been irreversibly damaged.
How does the depletion of elastin damage breathing?
The tissue containing elastin would usually spring back into place to force air out during resting breathing. In emphysematous lungs, the tissue is permanently stretched and the lungs can’t force all of the air out. Also, the alveoli can burst.
How does emphysema cause SHORTNESS OF BREATH?
Because the lungs can’t force out all of the air, it is hard to get fresh air in to replace it. Also, the smaller surface area means less air is being absorbed into the blood so the patient tries to breathe rapidly to get more in.
How does emphysema cause a CHRONIC COUGH?
It is a consequence of the body’s effort to remove damaged tissue and mucus that can’t be removed because all of the cilia have been destroyed through smoking
How does emphysema cause a BLUISH SKIN COLOURATION?
It is due to the poor levels of oxygen in the blood as a result of poor diffusion rate in lungs
