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Biology 2nd Baccalaureate

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4.1.2. Lungs


Lung anatomy

Pulmonary lobes

The lung lobes are the spongy, elastic masses into which the lungs divide. The right lung has 3 lobes, while the left only 2.

They are located inside the rib cage formed by the ribs, the sternum, the vertebral column and the diaphragm, which is a muscle whose contraction allows to increase the volume of the thoracic cavity.

Answer in your notebook

4.3.- Why do you think the left lung has a different number of lobes than the right?

Pulmonary alveoli

The pulmonary alveoli are tiny sacs located at the end of the bronchioles, with very thin walls, surrounded by numerous blood capillaries, which allow the exchange of gases between the air and the blood.

Each person has about 400 million pulmonary alveoli, which allows to have a respiratory surface to exchange gases of about 100 m2.

Activity: Pulmonary alveoli.


The pleurae are two membranes that surround the lungs and that have a fluid between them that allows the lungs to slide into the chest cavity during respiratory movements.

Pleura interna y externa cubriendo cada pulmón

By Cancer Research UK uploader (Own work) [CC BY-SA 4.0], via Wikimedia Commons

Activity: A system of ducts carries air from the atmosphere to the blood.

Activity: The lungs.

Activity: Parts of the lungs. (No registration required)

Activity: Parts of the respiratory system.

Activity: Anatomy of the respiratory system.

Activity: The respiratory system.

Activity: The respiratory system.

Animation: Basic aspects of breathing.

Game: Parts of the respiratory system.

3D model: Anatomy of the lung.

Do it yourself: Inflatable lung model.

Answer in your notebook

4.4.- What happens when we choke?


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.