1.6.10

Breathing

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Breathing

Inspiration (breathing in) and expiration (breathing out) involve many parts of the thorax moving in the following steps:

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Inspiration

  • The diaphragm contracts and becomes flattened.
  • The internal intercostal muscles relax and the external intercostal muscles contract, moving the ribcage up and out.
  • The thorax volume increases, forcing air into the lungs because of decreased internal pressure.
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Expiration

  • The diaphragm relaxes and becomes dome-shaped.
  • The internal intercostal muscles contract and the external intercostal muscles relax, moving the ribcage downwards and in.
  • The thorax volume decreases, increasing internal pressure.
  • Air is forced out of the lungs.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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