L21- Asthma and COPD Flashcards
What’s the difference between asthma and COPD?
Asthma is primarily irreversible. Asthma is reversible, though if left untreated can lead to iirreversible changes in lung function.
What’s FEV1?
The volume of air that can be exhaled from the lungs in one second, after max inspiration
What’s PEFR?
Max. flow rate developed by the lungs after a maximal inspiration.
What is asthma?
A chronic disease of the lungs, involving paroxysmal obstruction of the airways. Predominantly inflammatory
What is chronic obstructive pulmonary disease? COPD
Chronic disease with narrowing of peripheral airways in the lung. Poorly reversiblle. Combined bronchitis and emphysema. Predominantly inflammatory
What is asthma caused by?
Genetic factors
Early environmental influences eg maternal smoking
too-clean environment
What is status asthmaticus?
Severe acute asthma attack that isn’t readily reversed. Medical emergency, can be fatal.
What has changed in an asmathic airway?
- More submucosal glands
- More muscle
- Lots of immunal cells in the submucosal layer
- Basement membrane is thicker
- Loss of ciliated epithelium
So more mucus clogging, and more muscle so muscle contractions block airways more, and less cilia to remove the mucus
Asthma attacks are usually biphasic. What are the 2 phases?
Early phase- bronchospasm
Late phase- Inflammatory phase which usually compromises airways more.
How do immune cells acquire the antibody to be ready to interact with the allergen in allergic asthma?
- Antigen presenting cell interacts with a T helper cell.
- Activated T cell releases cytokines (interleukins)
- These activate other immune cells- eosinophils and mast cells.
- The mast cells then have the antibody and can interact with the allergen.
How do mast cells cause bronchospasm?
When antibodies on the mast cells link to antigens, the mast cell degranulates and releases histamine and other mediators.
Later, leukotriene B4 and prostaglandin D2 are made from membrane lipids. These factors cause bronchospasm.
What’s attracted to the histamine and other signals released by mast cells?
Cells including eosinophils which release toxic proteins that damage the respiratory epithelium (desquamation).
They also release various growth factors that cause sensitizing of the epithelium to further allergens. BAD.
What does histamine cause?
Contraction of smooth muscle, increased bronchial secretions
What do chemotactic factors cause?
Infiltration of lung tissues by neutrophils and eosinophils
What do later mediators- leukotrienes and prostaglandin cause?
Contraction of smooth muscle, increased vascular permeability, increased bronchial secretions
