Lesson · S.1.2
The respiratory system
How air moves from the atmosphere into the blood, and why the respiratory and cardiovascular systems cannot be studied apart.
ObjectiveS.1.2Read2 minExam weightHuman Anatomy and Physiology ≈ 41% of Science
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See editions and pricing →What you will be able to do
- Trace the path air takes from the nose to the alveoli.
- Explain why gas exchange happens only at the thin alveolar wall.
- Describe how the diaphragm, intercostal muscles, and brainstem work together to control breathing.
What the lesson concludes
- Air travels nose or mouth, pharynx, trachea, bronchi, bronchioles, alveoli.
- Gas exchange happens only in the alveoli, by diffusion, because their walls are thin.
- The right lung has three lobes, the left has two, since the heart occupies space on the left.
- The diaphragm and intercostal muscles drive breathing by changing lung volume and pressure.
- Blood pH and carbon dioxide levels, monitored by the medulla oblongata, set the breathing rate.