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Human Body Systems

The respiratory system, gas exchange and lung disease

  • 3 things to know
  • AS 2

Overview

The trachea and alveoli, inhalation and exhalation, gas exchange and what affects its rate, cystic fibrosis and its cause, and emphysema and breathlessness.

What you need to know

Answer each one before you reveal it.

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Key term

What are the main structures of the respiratory system?

Key term

How is the trachea adapted to its function?

Key term

How are alveoli adapted for gas exchange?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What are the main structures of the respiratory system?

    Model answer

    The respiratory system includes the nose, trachea, bronchi, bronchioles and alveoli, with the diaphragm and intercostal muscles. Air passes down the airways to the alveoli.

  2. 2

    How is the trachea adapted to its function?

    Model answer

    Rings of cartilage keep the trachea open during breathing. Ciliated cells and mucus trap and remove dust and microorganisms.

  3. 3

    How are alveoli adapted for gas exchange?

    Model answer

    Alveoli have a very large surface area and walls one cell thick. A dense capillary network maintains a steep concentration gradient.

  4. 4

    How does inhalation occur?

    Model answer

    The diaphragm contracts and flattens, and the external intercostal muscles raise the ribs. Chest volume increases, pressure falls and air flows in.

  5. 5

    How does exhalation occur at rest?

    Model answer

    The diaphragm and intercostal muscles relax, and the lungs recoil. Chest volume decreases, pressure rises and air flows out.

  6. 6

    What factors affect the rate of gas exchange?

    Model answer

    The rate depends on surface area, the thickness of the exchange surface and the concentration gradient. Fick's law summarises the relationship.

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