Life Cycle - Human Biology (3A)

  • Exploring  external signs of internal systems.
  • Analyzing how some of the internal systems work.  
  • organ
  • system
  • box of bones
  • mirrors (if not working with partners)
  • magnifying lens
  • skeletal model
  • stethoscopes

Students examine their body.


The internal body structure is very difficult for children to imagine.  We do not have corpses available for students this young to learn about internal anatomy.  People are left with their outside body to help decipher what their inside body looks like.  In this activity, the students are looking for external clues as to how their insides are working.  External names are head, abdomen, legs, arms, torso, and fingers. But under each of these external parts are the organs that make our body work as a fine-tuned machine.

  1.  If you have a skeletal model, ask students if the outside of our body reflects the inside.  Students should understand that our entire form is because of the structure of our skeleton.  The outside can help us understand the inside.  
  2. There are 10 tasks that the students observe which are listed under "body parts."  The students will then describe what they see and then try to interpret what systems the various parts belong to.  Each of the parts of the body is explained below.  You should leave adequate time to go over each of the parts so the students understand what they actually observed.  
  1. MOVEMENT OF CHEST (up and down) - RESPIRATORY  
    When air enters the lungs, they "blow up" like a balloon.  The expanded lungs push on the rib cage and make the entire chest move up and down. Students should use a stethoscope to listen to their lungs.  They can put the stethoscope on their back to listen.  It is much better to put the stethoscope on skin.  So if they have a partner they might want to listen to the lungs through their back.  But if the student is doing it their body, they can listen from their front. 
  2. NAILS (tips of fingers and toes) - SENSORY
    The nails are modified outer skin cells.  New nail cells take place as the nail moves forward and grows in length.  The crescent or moon at the base of the nail is called the lunula which is the living nail. Use the magnifying lense to look at this are closely.
  3. PULSE (beating) - CIRCULATORY
    A pulse is caused when blood goes through the arteries of the heart.  The heart is a strong muscle that "squirts" blood through the arteries as the blood leaves the heart.  The blood will return through the veins, but this action does not produce a pulse.  Use the stethoscope to listen to their blood move, they can either listen to their own heart or they can listen on their wrist or neck. 
    Students should move the skin under the eye down, to see the pink capillaries. If they do not have a partner, they will require a mirror.  You can see very small blood vessels. 
    Blood vessels are difficult to observe.  Have students look at either their underside of their tongue using a mirror or their partner's tongue.  They will see thick blue lines (veins), thick pink lines (arteries) and tiny hair-thin lines which are capillaries.  Arteries take the blood away from the heart, the blood is rich in oxygen and is red.  Veins take blood that has lost its oxygen toward the heart and the blood looks blue.  Capillaries are a system of blood vessels that join the veins and arteries.  When students look at the fold under their eye (pull slowly down to expose a small area), they will see capillaries.  
    To observe their vertebrae have students touch their back or partner's back midway.  Have them press slightly so they can feel the segmented vertebrae. The students can feel the bone better if the other student hunches over.  Students can also feel their own vertebrae that run along the middle of their back.  Have students use the bag of bones to observe where the vertebrate is located. 
    The skin and eyes are part of several systems, but they have to do with the senses.  Note that we are using the sensory system which is not a real system.  Most elementary text  books use sensory as a system and this is probably easier for children to understand.  Students may ask you about goose pimples which are an involuntary muscle reaction   which causes the hair to "stand on end."     
    The biceps get large as you flex your muscle.  Muscle cells contract and become larger. Students should make a muscle slowly.  The partner should feel the muscles and how they contract as the muscles is being made. 
    In this activity have the students just bend their arm with no force.  If you add no force nothing will happen. Muscles can only contract.  
    Hair is a modified form of skin cells.  Hair cells are produced at the embedded tip of  the hair follicle in the skin.  Students should use a magnifying lens to look at the hair follicles.  
  1. In the conclusion, we ask the students to determine which system does the human body most reflect.  The skeletal system basically controls the overall shape of the human body. 

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