Breathing andRespiration

Breathing andRespiration

1. Breathing

   • Respiratory system
     • In a nutshell: Breathe in so Oxygen diffuses into bloodstream, breathe out so CO2 diffuses out of bloodstream
     • To Inhale
       • 1. Intercostal muscles contract pulling ribcage upwards
       • 2. Diaphragm contracts, causing it to flatten
       • 3. (1) and (2) cause increase in volume of Thorax
       • 4. As a result, body has lower conc. of air than outside, so air goes in
     • To Exhale
       • 1. Intercostal muscles relax, so ribcage moves downwards
       • 2. Diaphragm relaxes, returning to domed shape
       • 3. (1) and (2) Cause reduction in volume of thorax
       • 4. As a result, body has higher conc. of air than outside, so air goes out
   • Alveoli provide HUGE S.A, with blood capillaries, so gases readily diffuse into and out of blood
     • Healthy person breathes all the time, but may stop due to disease or injury. Can be helped though:
       • Negative pressure ventilators.
         • CAUSES air to be drawn in
       • Positive pressure ventilators
         • FORCES air in

2. Respiration

   • Releases energy for lots of things:
     • 1. Build up larger molecules from smaller ones
     • 2. Animals use it to MOVE (muscles contract)
     • 3. Mammals and birds use it to keep them warm
     • 4. Plants use it to build sugars etc. in amino acids to proteins

3. Circulation

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