Respiratory Pathogenesis from ALL of module

Question 1

outline the early/immediate reaction in asthma

Answer 1

1. Eliciting agent (allergen or non-specific stimulus) stimulates mast cells leading to 2 outcomes:

• production of different mediators like spasmogens,

-

• promoting bronchospasm and bronconstriction
  production of chemotaxins, which initiate the late phase

Question 2

outline what happens in the late reaction of asthma

Answer 2

1. inflammation causes recruitment of eosinophils to maintain the inflammatoin + activates and other leukocytes

2.mucosal oedema and muscle hypertrophy occurs, narrowing the lumen

3. epithelial cells produce chemokines to attract more Th2 cells and eosinophils
4. repeated inflammation leads to airway remodelling

Question 3

outline 5 steps of the pathogenesis in ARDS

Answer 3

1. damaging stimulus to lung
2. this leads to damage to cells lining the alveoli and damage to the alveolar capillary endothelium, leading to increased permeablility
3. this leads to interstitial oedema and high protein exudation into the alveoli, which impairs oxygen gas exchange
4. this can lead to either a good outcome with regenerate of type II alveolar lining cells, OR a bad outcome with inflammation of the interstitium.
5. this leads to organisation of scar tissue, leading to interstitial fibrosis, which then becomes marked intersititial fibrosis (honeycomb lung), and can then cause death

Question 4

what are the 4 steps in IPF morphology in the disease IPF

Answer 4

1. stimulated fibroblasts deposit collagen and ECM excessively for an extended time
2. patchy interstitial fibrosis worses over time
3. fibroblastic foci - become more collagenous and less cellular
4. causes collapse of alveolar wall and formation of cystic spaces (honeycomb lung)

Question 5

outline the 5 steps involving how low surfactant levels leads to lung tissue changing into fibrin hyaline membrane

Answer 5

1. low surfactant
2. lung collapse
3. leads to hypoxia
4. causes pulmonary vasoconstriction and alveolar epithelial damage
5. produces fibrous exudate that causes free radicals to change structure of lung tissue into fibrin hyaline membrane

Question 6

outline the 4 steps that happen in the first 3 weeks to someone that acquires TB

Answer 6

1. inhaled mycobateria engulfed by macrophages
2. the mycobacteria maipulate endosomes in macrophages to be able to HIDE in macrophages
3. this causes defective phagolysosome formation
4. mycobacteria will then proliferate in the endosomes in macrophages, usually leading to mild flu symptoms

Question 7

outline 6 steps of what happens towards the end of the first 3 weeks of TB infection, regarding steps before granuloma inflammation and the formation of epithelioid macrophages.

Answer 7

1. Macrophages that have phagocytosed mycobacteria drain to lymph nodes and prime lymphocytes, causing T cells to be recruited to the lung

2.antigens from mycobacteria displayed on macrophage surface and presented to T cells.

3. T cells are converted to Th1 cells
4. Th1 cells activate more macrophages for phagocytosis by secreting interferon-𝛄
5. Monocytes are also recruited to release free radicals and Reactive Oxygen species, causing necrosis
6. this causes granuloma inflammation and the formation of epithelioid macrophages

Question 8

outline how dissemination can occur in TB and state:
- what happens if the pulmonary vein is involved
- what happens in the pulmonary artery is involved

Answer 8

Dissemination can occur in TB when caseating TB granuloma erodes into lung vasculature

If pulmonary vein involved:
- systemic dissemination to organs like liver, kidney and spleen

If pulmonary artery involved:
- lymph drainage to right side of heart, leading to miliary TB of lung