How is the mammalian gaseous exchange system adapted to its functions?

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  • Nasal  cavity;  has  cells  that  produce  mucus;  that  together  with  hairs/cilia;  trap  and  propel dust/microbes  to  the  pharynx  to  be  breathed  out/swallowed;  cavity  is  supplied  with  capillaries; that  warm  the  air  for  faster  flow  in  the  channels;  
  • Epiglottis;  covers  the  trachea  during swallowing;  so  that  particles  of  food  and  water  may  not  enter  the  trachea;  
  • Trachea  and  bronchi; have  cartilage  rings;  to  keep  the  passages  open/prevent  them  from  collapsing;  so  that  air  moves in  and  out  freely  and  continuously;  are  also  lined  with  mucous  membranes  which  have hairs/ciliated;  whose  movement/wafting  push  out  dust  particles  collected  in  the  passages  into the  pharynx;  richly-supplied  with  blood  vessels;  to  warm  the  air;  for  faster  flow;  lungs;  
  • Have numerous  alveoli;  to  increase  the  surface  area  for  gaseous  exchange;  alveoli  have  a  thin epithelium;  to  reduce  the  distance  through  which  gases  diffuse  for  easier  and  faster  diffusion; alveoli  are  moist;  to  dissolve  oxygen    for  faster  transport;  lungs  are  spongy;  because  of  many air  sacs  that  contain  a  large  amount  of/volume  of  air;  
  • Lungs  are  also  supplied  with  many  blood vessels;  for  transportation  of  gases;  they  are  also  supplied  with  a  network  system  of  trachea, bronchi  and  bronchioles;  to  provide  an  efficient  system/large  surface  area  for  gaseous exchange;    
  • Lungs  are  enclosed  in  a  pleural  membrane;  which  secrete  pleural  fluid;  that  protect the  lung  surface;  lubricate  the  chest  cavity;  allowing  smooth  movement  of  lungs  as  they  change volumes; 
  •  Ribs  have  intercostal  muscles;  that  moves/contracts  and  relaxes  to  allow  for  inhalation and  exhalation;  ribs  also  protect  the  lungs;  has  the  diaphragm  muscles  whose  contraction  and relaxation  leads  to  inhalation  and  exhalation  respectively;  
  • Max.  20  mks 

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