PPT 16: Asthma Flashcards
Exam 3
Airway diameter (resistance) is determined by what 3 things?
- Contraction and relaxation of smooth muscles
- ANS input
- Greatest resistance is in medium bronchi
What is the patho behind asthma?
Airway inflammation Mucosal thickening, plugs
Contraction of airway smooth muscle
What are the suspected reasons behind increased asthma prevalence?
- Infant second-hand smoke
- Worsening air quality
- Hygiene hypothesis
What are the symptoms of asthma?
- Wheezing, breathlessness, chest tightness, coughing
- ↑ at night, early morning
What are the measurements for asthma testing?
FEV1
PEF
What is PEF testing?
- Peak expiratory flow
- Maximum flow of forced expiration
What is FEV1 testing?
- Bronchial hyperreactivity testing
- Fall in forced expiratory volume in 1 second provoked by inhaling increasing concentrations of histamine or methacholine
What are the treatment modalities for asthma?
Contraction of smooth muscle
- Beta adrenergic agonists
Edema and cellular infiltration
- Anti-inflammatory agents
Extrinsic or atopic asthma is also known as _______
Type 1 Hypersensitivity Reactions
What are the mediators responsible for in the early asthma reaction?
- Diffuse throughout airway wall
- Cause muscular contraction and vascular leakage
- Immediate bronchoconstriction
What are the 3 mediators in the early asthma response?
Histamine, PGs, and leukotrienes
What are the mediators responsible for in the late asthma reaction?
Occurs 2-8 hours after immediate effects
- Sustained bronchoconstriction
- Cellular infiltration
- Mucous hypersecretion
The early asthma reaction is mediated by ____ cells, while the late reaction is mediated by ______
early: mast cells
late: WBCs
What kind of cells is mucus produced by?
Produced by goblet and epithelial cells
Mucus is composed of?
- 95% water
- 5% glycoproteins
Mucus is has increased ____ in asthma
viscosity
What is the role of mucus?
Defense against irritants and microorganisms
Describe the type 1 hypersensitivity reaction in detail
1st exposure:
1. dendritic cell on mucosa processes allergen, then turns into an antigen presenting cell → MHCII receptor presented on antigen presenting cell surface to activate immune response → migrates to regional lymph node and presents to T cell
2. T cell releases IL4 → activates B cells → B cells turn into plasma cells (antibody producing factories) and produce IgE or the B cells turn into B memory cells
- Dupixent (monocloncal antibody) - blocks IL4
3. IgE binds to surface of mast cells → sensitization of mast cells and basophils
2nd exposure: allergic reaction
1. Allergen binds to IgE antibodies on mast cells → Degranulation
2. Histamines and leukotrienes are released
3. Allergy symptoms
The difference between a type 1 hypersensitivity reaction in allergies and asthmatics is that asthma has less _______
histamine - more leukotriene and PG
Differentiate between PANS and SANS airway control
PANS - vagus nerve, contracts bronchiolar SM (M3)
SANS - relaxes bronchiolar SM (B2), circulating catecholamines