Pressure changes that drive inspiration and expiration — practice questions

Question 1 · difficulty L1 · recall

During normal quiet inspiration in a healthy adult, which combination of muscle activity occurs?

• A. The diaphragm contracts and the external intercostal muscles contract
• B. The diaphragm relaxes and the internal intercostal muscles contract
• C. The diaphragm contracts and the internal intercostal muscles contract
• D. The diaphragm relaxes and the external intercostal muscles relax

Question 2 · difficulty L1 · recall

What happens to the diaphragm during normal inspiration?

• A. It relaxes and becomes more dome-shaped
• B. It contracts and flattens
• C. It closes the glottis
• D. It compresses the lungs directly

Question 3 · difficulty L2 · understanding

During quiet expiration the diaphragm mainly:

• A. contracts strongly
• B. remains permanently flattened
• C. moves downward actively
• D. relaxes

Question 4 · difficulty L2 · understanding

During quiet inspiration intrapulmonary pressure becomes:

• A. zero absolute pressure
• B. slightly lower than atmospheric pressure
• C. equal to venous pressure
• D. higher than atmospheric pressure

Question 5 · difficulty L2 · understanding

During quiet inspiration the diaphragm:

• A. contracts and reduces thoracic volume
• B. relaxes and becomes more dome-shaped
• C. does not move
• D. contracts and flattens

Question 6 · difficulty L2 · understanding

Why does air enter the lungs during inspiration?

• A. Atmospheric pressure becomes zero
• B. Intrapulmonary pressure rises above atmospheric pressure
• C. Intrapulmonary pressure falls below atmospheric pressure
• D. The lungs actively pump air inward

Question 7 · difficulty L3 · application

During quiet inspiration, the external intercostal muscles contract. What is the immediate mechanical effect?

• A. Intrapulmonary pressure rises above atmospheric pressure
• B. The ribs move inward and thoracic volume falls
• C. The diaphragm relaxes and abdominal pressure disappears
• D. The ribs and sternum move upward and outward, increasing thoracic volume

Question 8 · difficulty L3 · application

A person's thoracic cavity increases in volume while intrapulmonary pressure becomes slightly lower than atmospheric pressure. Which event should follow?

• A. Air flows into the lungs
• B. Air flows out of the lungs
• C. No air movement occurs
• D. The lungs collapse immediately

Question 9 · difficulty L5 · analysis

A temporary condition prevents the diaphragm and external intercostal muscles from contracting, but the airways remain open. Which part of normal quiet breathing is most directly impaired?

• A. Diffusion of oxygen across the alveolar membrane only
• B. Generation of the thoracic-volume increase required for inspiration
• C. Binding of oxygen to haemoglobin
• D. Conversion of carbon dioxide to bicarbonate