Life Cycle - Human Biology (1A)
Lab 

   
OBJECTIVES:
  • Discovering the human nervous system.
  • Exploring involuntary and voluntary reactions. 
VOCABULARY:
  • brain
  • nervous system
  • reflex
  • senses
MATERIALS:
  • ice cubes
  • towels
  • flashlight
  • large white shirts (optional) 

Students find sensitive parts of their bodies.


BACKGROUND:

The organs of your body are composed of tissues that are composed of many cells.  Cells can be specialized to perform a particular function such as contraction (muscle) or sensation (nervous).  Nerve cells or neurons conduct nerve impulses to and from the body of the cell.  They transmit impulses all around your body.  Touching something hot causes impulses to move through the neurons and relay the message to the brain.  It is like a train track of nerve cells that brings the message to your brain. Nerve cells are very delicate and cannot be regenerated.  

The nervous system controls all other functions in the body.  It accomplishes this by two mechanisms which we will group into voluntary actions and involuntary actions.  The nervous system simulates movement, digestion, circulation, and the direction of all other body parts.  

The somatic nerves control the voluntary cells which are under conscious control.  If you want to raise your hand, and do so, this is a voluntary motion.  The autonomic nerves control the involuntary motions of your body.  These nerves keep check of your body continuously by maintaining temperature, composition of blood, heart beat, digestion, and excretion.  These are activities that you do not even think about.  Even stress when your blood pressure, pulse rate, and blood sugar become elevated, is controlled by the autonomic nerves.  The somatic and autonomic systems work together.  Skin exposed to cold air becomes "blue," this is autonomic.  At the same time impulses are sent to the brain for sensations of cold, this is somatic.

PROCEDURE:
  1. This lab is to get students to realize that their nervous systems are very complicated.  Use large white shirts as doctor uniforms.  Select students that will be the doctor, and who will administer the activity.  Put the suit on the students and give that student a piece of ice.  If you have enough parent volunteers, you may want a parent to take the role of the doctor. 
       
  2. Break the class into groups or patients in front of each doctor.  The doctor will put the ice cube on several areas of the patient's body.  The purpose of this is so students can find where the ice feels the "coldest."  The doctor should place the ice on the back arm, forearm, palm, hand, and fingertips.  The patients are supposed to figure out where the ice feels coldest on their bodies.  They should all feel that the fingertips sense the cold with the greatest sensitivity.  
       
  3. You may want the doctors to also use the "needle" to find the most sensitive part of the arm or leg.  However, you must select those students who will not try to really "stick" it to their fellow students.    The needle can be the back of a pen or tongue depressor.  This part should be done with adult supervision. 
       
  4. Another activity that illustrates the fact that nerves control motion is for students to find their knee reflex.   A reflex is an action in response to a stimulus, occurring without conscious effort or thought.  Have the patient cross his knee and the doctor uses the reflex hammer to find the spot where the knee will jerk.  This will need supervision, because finding that spot takes a little skill. 
      
  5. The doctor can also perform an examination of the eyes to see if the nerves of the eye react to light.  Have one student shine a small flashlight into another student's eye  to observe what the pupil of the eye will do.  It will move, which is an autonomic response to the light.   Only do this lab if an adult guides the students. 

    You may want to see if any of your studentís parents are doctors or nurses.  They may be able to add to the realism in the classroom.   This lab is for students to realize that their bodies move in very planned motions.  There are motions that we don't have to think about such as involuntary motions, and there are some that we control such as, voluntary motions.  The nervous system controls this movement.  The parts of our bodies are somehow connected and work in unison, for if they did not, they would not work.   

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