II. Approach to Respiratory Tract Pathology – NUS Pathweb

For large and complex topics such as this, it is helpful to break it down into smaller pieces that still connect, so that everything makes sense of the Big Picture.

Here are several approaches:

1. ANATOMICAL

Upper respiratory tract (Nose, pharynx, paranasal sinuses, larynx (some include trachea too)
- You can subdivide the conditions according to aetiology, eg. inflammatory/infectious, neoplastic etc.
- The common and important conditions are covered well in your lecture notes and will not be further highlighted here
Airways (trachea, bronchi, bronchioles, down to respiratory bronchioles)
- Different conditions affect airways of different sizes, eg. bronchiectasis and chronic bronchitis (larger airways); emphysema and bronchiolitis (smaller airways) etc.
- Conditions vary according to aetiology, eg. inflammatory, neoplastic, infectious etc. and abnormalities can lead to obstruction of air flow
Lung parenchyma
- Alveoli, capillaries, interstitium
- In terms of function, the above form the gas exchange surface which is very important for the main function of the lung – absorbing oxygen and secreting carbon dioxide
- Specific components of alveolar septa (let’s follow the direction of blood to air)
  - Capillary endothelium
  - Basement membranes
    - Of capillary and alveolar wall
    - Interstitial tissue (if present) – collagen, elastic, fibroblasts, smooth muscle, few chronic inflammatory cells
  - Alveolar epithelium (pulmonary surfactant lies on top of this)
  - Alveolar macrophages (within alveolar spaces)
Pleura
- Diseases of the pleura can affect lung function as well, eg. pleural fibrosis decreasing lung expansion
- Some notable conditions: Pleural fibrosis, calcifications and plaques (eg. TB, pneumoconiosis); infections (eg. empyema); malignancy (mesothelioma – related to asbestos exposure)
Blood vessels
- Large to small; arteries (eg. pulmonary embolism); veins (eg. chronic venous congestion )
- Conditions can be haemodynamic (eg. pulmonary embolism, pulmonary hypertension) or inflammatory (eg. vasculitis)

2. AETIOLOGICAL

• VITAMIN C (eg. Vascular, Infectious, Toxic, etc.) – this is covered in the mindmaps at the bottom of this page.

Note that the mindmap is not comprehensive, and you can slot in other conditions as you read about them eg. chronic venous congestion

• This is one of the most complete ways of categorizing lung disease, and you can take note of the anatomical component and functional aspects along the way.

3. FUNCTIONAL

This applies mostly to Chronic lung diseases of a non-infectious and non-neoplastic nature
Lung disease can be classified into two main functional abnormalities:
- Obstructive
- Restrictive
With a living patient, lung function tests are used to determine the pattern. Eg. total lung capacity and expiratory flow rate (measured by forced expiratory volume at 1 second).
These two main patterns are caused by different conditions, with some overlaps.

Refer to "Mindmaps: Obstructive vs Restrictive Lung Diseases" - at the bottom of this page

MINDMAPS: LUNG DISEASES 1 AND 2

If you can't play the video, watch it here on YouTube: https://youtu.be/DFjTGSrFP8o

If you can't play the video, watch it here on YouTube: https://youtu.be/MF3edGtlYCA

MINDMAPS: OBSTRUCTIVE VS RESTRICTIVE DISEASES 1 and 2

If you can't play the video, watch it here on YouTube: https://youtu.be/UZj023LXWPQ

If you can't play the video, watch it here on YouTube: https://youtu.be/c47HyvdGzeI

I. Function

II. Approaches to Respiratory Pathology

III. Clinical Manifestations of Respiratory Disease

IV. Respiratory Tract: Talking Pots and Slides

V. Respiratory Tract: Quiz - Two Mystery Cases

Respiratory Tract: Study Notes and One Page Summary

Respiratory Tract Chapter Home

Pathology Demystified

MINDMAPS: LUNG DISEASES 1 AND 2

MINDMAPS: OBSTRUCTIVE VS RESTRICTIVE DISEASES 1 and 2

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