Biology MOD 3 revision

Set of revision cards for the final module in GCSE Biology

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BREATHING SYSTEM

Thorax -> Upper part of the body

Diaphragm seperates the THORAX from the lower part.

Air comes in through the Trachea, and then into the bronchi, which seperates into two tubes, each called the bronchus. One bronchus goes into one lung each, where it seperates into little bronchioles. They have alveoli on the end of them. Which are little air sacs where gaseous exchange takes place.

BREATHING IN:

  • Intercostal muscles and diaphragm contract
  • Thorax volume increases
  • Pressure is increased and air is breathed in

BREATHING OUT:

  • Intercostal muscles and diaphragm relax
  • Thorax volume decreases
  • Air is forced out
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DIFFUSION THROUGH CELL MEMBRANES

Alveoli and Villi

ALVEOLI is where gas exchange takes place in the lungs.

It transports oxygen into the bloodstream and removes waste carbon dioxide.

It is specialised so the diffusion rate is quicker:

  • Thin Walls
  • Massive Surface Area
  • Good Blood Supply

VILLIincreases the surface area in the small intestine.

This transports the digested food quicker.

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