Life Cycle - Human Biology (3A)
Post Lab 

  • Analyzing components of the respiratory system.
  • Exploring human systems in detail.
  • alveolus or air sac
  • bronchiole
  • bronchus
  • esophagus
  • larynx
  • lungs
  • respiratory
  • trachea
  • worksheet

Students look at how humans breathe. 



It is the respiratory system that enables our bodies to breathe in oxygen and breathe out carbon dioxide.  Without oxygen, we cannot live for more than a few minutes.  All the cells in the body use oxygen to aid in the process of converting food into energy.

The process by which we breathe is as follows.  Oxygen is taken in through the nose (nasal cavity).  Oxygen is a component of air.  From the nose the air enters the pharynx (the throat cavity behind the mouth).  From there the air passes through the voice box or larynx and then into the windpipe or trachea which is supported by stiff cartilage rings that one can feel at the throat.  The trachea becomes divided at the lower end into two tubes, called bronchi (bronchus - singular).  Within these pathways, air is warmed, filtered, moistened, and delivered to and from the lungs.  Each bronchus enters a lung (left and right) and divide up into narrower tubes called the bronchioles.  At the end of these tiny tubes are hundreds of tiny air sacs called alveoli (alveolus-singular).  These tiny air sacs in the lungs hold the air for a few seconds until the oxygen is diffused into the blood through capillaries.  Blood returning from the heart carries carbon dioxide which leaves the blood stream by diffusing into the air sacs which is then exhaled out by the lungs.

  1. Provide students with copy of worksheets.
  2. Go over each of the  words on their worksheet.
  3. Repeat the section above on how we take in air through our lungs.  Have the students label the parts of the respiratory system as you talk.  Give them clues on where each part belongs.  

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