lungs

• lungs:

  • found in thorax
  • protected by ribcage
  • supply oxygen to blood
  • remove carbon dioxide
• gas exchange is made of:

  • trachea - windpipe, air moves through
  • intercostal muscles - contract and relax to ventilate lungs
  • bronchi - air from trachea move into each lung, two 'branches'
  • bronchioles - bronchi split into this
  • alveoli - air sacs where gas exchange occurs
  • diaphragm - separates lungs from digestive organs, moves up and down for inhalation
• ventilation:

  • ribcage moves up and out the diaphragm - volume of chest increases
  • increased volume results in lower pressure
  • air is drawn into chest as air moved from the environment to lungs
  • opposite happens when exhaling
• gas exchange:

  • upon inhalation, alveoli fill with oxygen
  • blood in capillaries surrounding the alveoli is deoxygenated - has alot of carbon dioxide
  • oxygen diffuses into capillary
  • carbon dioxide diffuses into alveoli
  • person breathes out
• adaptations of alveoli:

  • small and arranged in clusters, creating a large surface area for diffusion to take place over
  • capillaries provide a large blood supply, maintaining the concentration gradient
  • walls of alveoli are very thin, meaning there is a short diffusion pathway
• breathing rate:

  • rate = number of breaths / number of minutes