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Respiratory System

0% mastered
Placing the respiratory system8%

A tide of airSystema respiratorium

An airway and an enormous folded membrane, arranged so that oxygen can cross into blood and carbon dioxide can leave.

Illustrated plate of the respiratory system
Primary role
Exchanges oxygen for carbon dioxide
Scale
~70 m² of exchange surface
Every day
About 20,000 breaths

Organs in this atlas 1

How it works as a whole

Air is drawn in not by suction from the lungs, which have no muscle of their own, but by the diaphragm dropping and the ribs swinging outward to enlarge the chest. Pressure falls, air follows. The airway branches some twenty-three times, warming and filtering as it narrows, until it ends in roughly 300 million alveoli — thin, wet sacs wrapped in capillaries. Folded flat, that exchange surface would cover a tennis court, all of it packed inside the ribcage.

Other key structures

  • DiaphragmThe muscle that actually does the breathing
  • Trachea & bronchiConducting airway — warms, filters, and humidifies
  • AlveoliWhere gas exchange happens, across a wall under a micron thick
  • PleuraSlick double membrane letting lungs glide against the chest wall

Connected systems

  • Cardiovascular SystemShares a circuit — the entire blood volume passes the alveoli
  • Nervous SystemBrainstem sets breathing rhythm automatically, day and night
  • Urinary SystemTogether they hold blood pH in a very narrow band

Common conditions

  • Asthma
  • COPD
  • Pneumonia
  • Sleep apnoea
  • Pulmonary embolism
  • Tuberculosis

The through-lineBreathing rate is set less by oxygen than by carbon dioxide: brainstem sensors read blood CO₂ and adjust the drive to breathe, which is why holding your breath becomes intolerable well before oxygen actually runs low.

Did you knowYou exhale roughly a glass of water a day simply as vapour — which is why breath fogs a cold window.

The path through this system

0 of 10 steps done — read it, walk it in 3D, then be asked about it.

Start: Lungs: the lesson
ReadLessonIntroLungs: the lesson

Structure and story of the lungs, layer by layer.

3 minGuided walk-throughDissectionIntroGuided dissection: lungs

Walk the lungs structure by structure, then cut inward layer by layer.

6 minMemo cardsQuizIntroLungs memo cards

Turn the cards on the lungs — structures, layers, key facts — and grade yourself.

4 minMultiple choiceQuizIntroLungs quiz

A multiple-choice round on the lungs, reshuffled every time.

4 minClick on the 3D modelQuizCoreFind the lungs structures

Click the named structures directly on the live 3D lungs.

5 minLabel the diagramQuizCoreLabelled diagram: Lungs

The lungs plate with its labels taken off: put each one back on its number, or draw it yourself first.

5 minMatch layersQuizCoreMatch lungs layers

Pair each layer of the lungs, outside in, with what it does.

4 minMatch pairsQuizCoreMatch lungs structures

Pair each structure in the lungs with its role.

4 minMultiple choiceQuizCoreRespiratory System quiz

A quiz pulling from every organ in the respiratory system.

3 minReadClinicalIntroLungs in the clinic

Where the lungs shows up in the clinic, and what goes wrong.

3 min