MEDICINE · RESPIRATORY FOUNDATIONS
A system-level first pass through ventilation, perfusion, airway physiology, pulmonary mechanics, pleura and pulmonary circulation.
USE THIS AS A CHAPTER
Core notes first. Questions second.This is the Respiratory equivalent of the Cardio chapter: a clear first map with original practice. The next depth layer will add topic-specific notes and a scored test.
CORE TOPICS
Mechanism creates the structure; clinical context tells you which mechanism matters in a question.
01 · VENTILATION & PERFUSION
Ventilation moves air to alveoli; perfusion carries blood through pulmonary capillaries. Gas exchange depends on their relationship, not either process alone. V/Q mismatch describes unequal regional matching, while shunt is the more extreme concept of blood reaching the arterial side without effective contact with ventilated alveoli.
Retrieve: Contrast ventilation, perfusion, V/Q mismatch and shunt in four short lines.
02 · OBSTRUCTION
Obstructive physiology reflects increased resistance to airflow, particularly during expiration. The exam frame is airway calibre, expiratory flow limitation and air trapping—not a drug list. Asthma and COPD are distinct clinical entities even though both can show obstructive physiology.
Retrieve: Why is obstructive physiology often described in relation to expiration?
03 · RESTRICTION
Restrictive physiology involves reduced lung expansion and reduced volumes. The conceptual causes can arise from lung parenchyma, pleura, chest wall or neuromuscular system. A good answer separates the physiological pattern from the anatomical site that may be causing it.
Retrieve: List four broad anatomical locations that can produce a restrictive pattern.
04 · GAS EXCHANGE
Gas transfer depends on alveolar ventilation, membrane diffusion, perfusion and oxygen carriage. Carbon dioxide diffuses readily, so an examination question often uses it to test the difference between ventilation failure and impaired oxygen transfer. Time course and work of breathing matter to interpretation.
Retrieve: Name three processes that can change gas exchange without naming a disease.
05 · PLEURA & MECHANICS
The lung and chest wall have different elastic tendencies; pleural pressure is part of the mechanical link between them. Pleural processes can therefore affect expansion even when the airway itself is not the central problem. Think mechanics before memorising a sign.
Retrieve: Why can a pleural process alter lung expansion without being an airway disease?
06 · PULMONARY CIRCULATION
The pulmonary circulation receives the entire cardiac output but normally operates at lower pressure than the systemic circuit. Questions can test how pulmonary vascular resistance, right-heart load and gas exchange intersect. Use a physiology map before jumping to a condition label.
Retrieve: Why is pulmonary circulation described as low pressure despite receiving the full cardiac output?
ORIGINAL QUESTION BANK 01
Core questions build the mechanism. NEET PG and Challenge questions ask you to discriminate between close physiological concepts.
B. Ventilation concerns air movement. Perfusion concerns blood flow, and diffusion concerns movement across the alveolar-capillary interface.
A. The core concept is increased airway resistance and flow limitation, often particularly evident during expiration.
D. Restriction can arise from parenchyma, pleura, chest wall or neuromuscular system. A coronary artery is not part of that anatomical map.
B. Both are gas-exchange concepts, but they are not synonyms. Shunt represents a more extreme lack of effective contact with ventilated alveoli.
B. The pleural space is part of the mechanical relationship between the lung and chest wall, so a pleural process can influence expansion.
B. The pulmonary circuit receives the entire output from the right ventricle but normally functions at lower pressure than systemic circulation.
B. Sorting the dominant physiological domain first makes later discrimination much more reliable.
B. A physiological pattern organises thought, but anatomy, cause, chronology and context make it interpretable.
B. Gas exchange is a system problem. The best answer looks for which component—or combination—is most relevant.
RESPIRATORY ROUTE
This foundation and bank are now linked from the Medicine index. Next we deepen Respiratory with airway disease and gas-exchange topic packs, then add its scored test.