Pathophysiology of asthma Flashcards

1
Q

How does inflammation cause airway dysfunction? (briefly)

A
→ Allergen inhalation 
→ Immune system response 
→ Airway inflammation 
→ Impaired airway function 
→ Wheezing, coughing, dyspnoea
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2
Q

What lifestyle factors make it more likely to get asthma?

A

→ Urban dwelling
→ Pollution
→poor diet
→ obesity

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3
Q

What is Ohms law?

A

→ Airflow is proportional to 1/resistance

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4
Q

What does the Hagen-Poiseuille law state?

A

→ As an airways radius decreases the resistance increases and airflow decreases dramatically

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5
Q

What determines the radius of the lumen?

A

→ The level of contraction of smooth muscle

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6
Q

What factors decrease the radius of the lumen even further?

A

→ Hypersecretion of mucus

→ Swelling

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7
Q

What is wheezing caused by?

A

→ Turbulent airflow

→ Increases resistance and decreases airflow

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8
Q

What is the first stage in the allergic response?

A

→sensitization
→ person breathes in allergen
→ Gets stuck in the airways
→ APC recognizes allergen as being harmful
→ Processes antigen to a helper T cell
→T cells mature and become TH2 cells
→ TH2 cells secrete cytokines like IL5
→ IL4 interacts with B cells and stimulates them
→ B cells proliferate and produce IgE antibodies
→ Antibodies bind to mast cells

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9
Q

What is the second stage in the allergic response?

A
→ Exposure
→ Allergen binds to antibodies 
→ Mast cells degranulate 
→Prostaglandins, LTs and chemokines are secreted 
→ Mediators bind to receptors 
→cause smooth muscle to contract 
→ Mediators attract TH2 and eosinophils 
→ Eosinophils migrate to airways and release reactive O2 species 
→ Second round of inflammation occurs
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10
Q

What is the early phase of the asthmatic response?

A

→ Initial degranulation of mast cells

→ After the first response the mediators are cleared and effects resolve themselves

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11
Q

What is the secondary phase of the asthmatic response?

A

→ Eosinophils and T cells being recruited several hours later

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12
Q

What are the changes in respiratory function observed in asthma?

A

→ FEV1 decreases
→ FVC is unchanged
→ FEV/FVC decreases <70%

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13
Q

What are the long term changes caused by uncontrolled asthma?

A
→ Smooth muscle is being constantly worked 
→ Hypertrophy of smooth muscle
→ More muscle takes up more space and contracts harder 
→ More goblet cells and mucus glands 
→ Infiltration of immune cells 
→ Epithelium Distruption
→ Basement Membrane thickening
→ ECM deposition and Fibrosis
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14
Q

What are the most effective treatments for asthma?

A

→ Beta 2 agonists and corticosteroids

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