• 11 parts
  • Checked October 2026

Pleural Membranes and Pressures Diagram

One lung in its pleural sac, then the three pressures that move air in and out.

Pleural Membranes and Pressures Diagram

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1 2 3 4 5 6 7 8 9 10 11
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Write the name of each numbered part.Answer key

  1. Lung
  2. Parietal pleura
  3. Visceral pleura
  4. Pleural cavity
  5. Chest wall
  6. Diaphragm
  7. Atmospheric pressure
  8. Intrapulmonary pressure
  9. Intrapleural pressure
  10. Transpulmonary pressure
  11. Air flowing in

Drawn for this site on 2026-10-03 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the lobes and fissures of the lungs

All 11 parts on the diagram

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Membranes 6

  1. Lung The organ inside the sac. Its airways branch from the bronchus that enters at its root.
  2. Parietal pleura The outer layer of the pleura. It lines the chest wall and covers the diaphragm.
  3. Visceral pleura The inner layer of the pleura. It coats the lung's surface.
  4. Pleural cavity The thin space between the two layers. It holds a film of pleural fluid.
  5. Chest wall The wall of the chest, with the ribs in it. The parietal pleura lines its inside.
  6. Diaphragm The sheet of muscle under the lung. The parietal pleura covers its upper surface.

Pressures 5

  1. Atmospheric pressure The pressure of the air outside the body.
  2. Intrapulmonary pressure The pressure inside the alveoli of the lung. It is also called intra-alveolar pressure.
  3. Intrapleural pressure The pressure within the pleural cavity. It is normally a little below atmospheric pressure.
  4. Transpulmonary pressure Intrapulmonary pressure minus intrapleural pressure. It keeps the lung expanded.
  5. Air flowing in Air flows in when intrapulmonary pressure falls below atmospheric pressure.

How this list was compiled: Every name read on 2026-10-03 and kept only where two independent sources give it. (1) Henry Gray, Anatomy of the Human Body (1918, public domain), The Pleurae, https://www.theodora.com/anatomy/the_pleurae.html : the pulmonary (visceral) pleura on the lung, the parietal pleura lining the chest wall and covering the diaphragm, the two continuous around the root of the lung, the pleural cavity between them. (2) Wikipedia, text only: Pleural cavity, Intrapleural pressure and Transpulmonary pressure, https://en.wikipedia.org/wiki/Pleural_cavity and https://en.wikipedia.org/wiki/Transpulmonary_pressure . (3) U.S. National Cancer Institute, SEER Training Modules, Mechanics of Ventilation, https://training.seer.cancer.gov/anatomy/respiratory/mechanics.html : atmospheric, intra-alveolar (intrapulmonary) and intrapleural pressure, and air flowing in when the pressure in the alveoli falls. (4) TeachMePhysiology, Mechanics of Breathing, https://teachmephysiology.com/respiratory-system/ventilation/mechanics-of-breathing/ : the pleural space and its fluid, intrapulmonary and intrapleural pressure, and transpulmonary pressure as the difference that keeps the lungs expanded. The drawing is our own. Licence: own work

The drawing: Drawn for this site on 2026-10-03 from plain geometry. Own original drawing; nothing traced or copied. Not to scale. Licence: own work

How it works

Each lung sits in a sac of two thin membranes, the pleurae, with a film of fluid between them. The first drawing names the layers. The second adds dials for the pressures that fill and empty the lung.

Read the full guide

Membranes

The visceral pleura covers the lung. The parietal pleura lines the chest wall and covers the diaphragm, and the two are one sheet, joined around the root of the lung. The pleural cavity is the thin space between them. Both layers and the gap are drawn far thicker than life.

Pressures

Atmospheric pressure is the pressure of the air outside. Intrapulmonary pressure is the pressure in the alveoli, and intrapleural pressure the pressure in the pleural cavity, normally the lowest of the three. The last two differ by the transpulmonary pressure. The needles show order only.

  • Intra means within: intrapulmonary is within the lung, intrapleural within the pleural cavity.

Questions and answers

What are the two pleural membranes?

The visceral pleura, which covers the surface of the lung, and the parietal pleura, which lines the chest wall and covers the diaphragm. They are one continuous sheet, folded back on itself around the root of the lung.

What is the pleural cavity?

The thin space between the visceral and the parietal pleura. It holds a film of pleural fluid, whose surface tension keeps the two layers close together, so the lung follows the chest wall as it moves.

What is the difference between intrapulmonary and intrapleural pressure?

Intrapulmonary pressure is the pressure inside the alveoli of the lung; it is also called intra-alveolar pressure. Intrapleural pressure is the pressure within the pleural cavity, which is normally a little lower than atmospheric pressure.

What is transpulmonary pressure?

The difference between the pressure in the alveoli and the pressure in the pleural cavity: intrapulmonary minus intrapleural. It is the force that keeps the lungs open.

How do I label the pleural membranes and pressures associated with the lungs?

Name the layers from outside in: parietal pleura, pleural cavity, visceral pleura. Then place each pressure where it is measured: atmospheric outside the body, intrapulmonary in the lung, intrapleural in the pleural cavity. This drawing is our own, made for practice.

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