lungs

• inspiration/inhaling


  -external intercostal muscles contract and internal intercostal muscles relax

  -this moves ribcage up and out

  -diaphragm flattens

  -volume of chest cavity increases

  -pressure inside the lungs drops below atmospheric pressure

  -forces air to rush into the lungs
• expiration/exhaling


  -external intercostal muscles relax and internal intercostal muscles relax

  -moves ribcage in and down

  -diaphragm moves up

  -volume of chest cavity decreases

  -pressure inside the lungs increases above atmospheric pressure

  -air rushes out of the lungs
• spirometer


  measures lung function. chamber filled with oxygen sat on a water tank. pen tracks movement of chamber to produce a trace.
• using a spirometer safely

  -disinfect/ sterilise mouthpiece

  -sufficient fresh oxygen in the chamber

  -carbon dioxide accumulates and could be dangerous- use soda lime to absorb

  -make sure subject is healthy- not asthmatic

  -ensure water level is below opening of the tubes
• tidal volume


  -volume of air moved in and out of the lungs in 1 breath @ rest

  -subject wears nose clip and breathes normally

  -measure amplitude of atleast 3 waves and calculate the mean
• vital capacity


  -largest vol of air that can be moved in and out of the lungs in one breath

  -measure difference between highest part and lowest trough
• residual volume


  -volume of air always left in the lungs even after the deepest breath
• dead space


  -air in bronchi, bronchioles and trachea that doesn't contribute to gas exchange
• inspiratory reserve volume


  -extra volume of air that is breathed in in a deep breath compared to tidal volume
• expiratory reserve volume


  -extra volume of air that is breathed out compared to tv
• calculating oxygen consumption


  -add soda lime to spirometer to absorb exhaled carbon dioxide and fill chamber with oxygen

  -as you breathe in you take in air from the oxygen chamber and carbon dioxide absorbed by soda lime

  -overall drop in volume

  -trace drops as more oxygen is used

  -draw a line at the top of the peaks

  -measure gradient over a given time period
• forced expiration

  -active (requires energy)

  -internal intercostal muscles contract

  -abdominal muscles contract forcing the diaphragm up

  -ribs pulled down hard