Year 11 Biology

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Year 11 Biology

• The Respiratory System

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The Respiratory System

• THE VARIOUS PARTS OF THE RESPIRATORY SYSTEM ARE-
• TRACHEA
• EPIGLOTTIS
• LARYNX
• BRONCHUS
• BRONCHIOLES
• ALVEOLI
• DIAPHRAGM

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• The air passes into the lungs down a tube called
  the TRACHEA. This is made up of rings of
  cartilage.

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• There are plates of cartilage at the top of the
  TRACHEA which widen at the point commonly called
  the Adams Apple.

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• This is actually the LARYNX or Voice Box.
• Occasionally this doesnt happen and we have all
  experienced feeling choking when food goes down
  the wrong way.
• At the bottom of the TRACHEA are 2 branches
  called the BRONCHI, through which air passes into
  either lung.
• Smaller and smaller branches, called BRONCHIOLES,
  extend out from the BRONCHI and at the very ends
  of these they form tiny sacs called ALVEOLI.

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ALVEOLI

• It is these that give the lungs their spongy
  texture.
• The linings of the ALVEOLI are very thin and only
  work well when they are moist and clean.
• When air is breathed in through the nose, it is
• FILTERED by the hairs at the entrance to the nose
  and by mucus.
• WARMED by blood vessels passing close to the
  lining of the nose.
• MOISTENED by water vapour.

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BREATHING IN

• When we breathe in, the cycle starts with the
  ribs lifting upwards and outwards.

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• This is caused by the contraction of the
  intercostal muscles which are situated between
  the ribs.

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• There is also movement in the body as the
  DIAPHRAGM contracts, changing from a dome shape
  to a flatter sheet.

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BREATHING OUT

• It relaxes when we breathe out, moving upwards
  back to a dome shape.

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GASEOUS EXCHANGE

• The ALVEOLI are in very close contact with the
  blood capillaries, which contain red blood cells
  and Haemoglobin

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• We have already seen that Haemoglobin carries
  oxygen and at this point in the CIRCULATORY
  SYSTEM it attracts the oxygen in the ALVEOLI.
• Whilst the oxygen is taken in, carbon dioxide is
  given out, into the Alveoli and is then breathed
  out.

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• So the RESPIRATORY SYSTEM has 2 main jobs
• To get oxygen into the body
• To get carbon dioxide out of the body.

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WHAT WE BREATHE

• As well as breathing in oxygen, we also breathe
  out a lot of oxygen.
• This is most important when we give mouth to
  mouth resuscitation.
• The air we INHALE contains 20 oxygen and 0.4
  carbon dioxide.

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• The air we EXHALE contains 16 oxygen and 4
  carbon dioxide.

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This is why we can give the kiss of life
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