ventilation

• summary

  • muscle contractions increase thus need more energy
  • aerobic respiration increases as cells need more 02
  • produce more C02 as a waste product
• during exercise

  • increase rate and depth of breathing= increased 02 to lungs+ blood and removes more C02
  • increased heart rate= transports more 02 and glucose to muscles(faster), removing additional C02
• control of breathing rate

  • controlled by ventillation centres in medulla oblongata
  • located at the base of brain, where the brain stem connects the brain to your spinal cord
• inspiratory centre

  1. sends nerve impulses along motor neurones to intercostal and diaphragm muscles
  2. these muscles contract and cause volume of chest to increase- intercostal muscles move ribcage up and out and diaphragm moves down
  3. increased area lowers pressure in lungs, to below atmospheric pressure-impulse sent to expiratory centre to inhibit its actions
  4. difference in air pressure causes air to move from high to low pressure- air flows into lungs
• • stretch receptors in the lungs are stimulated as they fill with air
  • impulses are sent back to medulla to inhibit the inspiritory centre
• expiratory centre

  • medulla sends nerve impulses to intercostal and diaphragm muscles
  • muscles will relax- diaphragh moves up and intercoastal muscles move ribcage down and inwards- volume of chest decreases
  • air pressure in the lungs increases above atmospheric pressure
  • air particles move from high to low pressure- air will flow out of lungs

  lungs deflate, stretch receptors become inactive= inspiratory centre not longer inhibited