Life Cycle - Human Biology (5A)
Post Lab 

   
OBJECTIVES:
  • Comparing how and where digestion takes place.
  • Explaining the different types of food molecules.
VOCABULARY:
  • calorie
  • carbohydrate
  • diet
  • enzyme
  • fat
  • mineral
  • protein
  • vitamin
MATERIALS:

Students use a worksheet to trace how  food goes through the human body.

 

BACKGROUND:

Food provides energy to help our bodies grow.  No one kind of food can fulfill all of the body needs, so we must eat a variety of foods in order to receive proper nutrition.  Nutrients in foods are chemical substances and are classified as carbohydrates, fats and oils (lipids), proteins, minerals, and vitamins.   

Carbohydrates contain carbon, hydrogen, and oxygen, and their "burning" is the body's usual source of energy for muscular work, body heat, breathing, and other functions.  Amino acids which are linked together to form proteins contain nitrogen and sometimes sulfur in addition to carbon, hydrogen, and oxygen.  Amino acids are essential to our bodies. Fats are made up of fatty acids and glycerol.  Fatty acids or unsaturated fats cannot be manufactured by our bodies so they must be supplied by our diets.  Vitamins and minerals are needed in small amounts and are needed to make chemical reactions happen in tissues.  In other words vitamins help a body run smoothly.  A normal healthy diet provides almost all of the vitamins one needs.
 
PROCEDURE:

  1. You may want students to critique What Happens to a Hamburger to see if the information in the book.  This book is essential correct. It is important for students to know that just because it is in a book, doesn't mean that it is correct.  You should always question what you read. 

  2. In this worksheet, students are asked to trace how sugars, starches, proteins and fats are digested in the body.  Students should be familiar with the parts of the digestive system.  However, they may not know that the duodenum is about 10 inches in length and is the shortest, widest, and most firmly attached portion of the small intestine.  

    Digestion begins in the mouth with some starches and sugars being broken down into simple sugars by an enzyme in the saliva.  Proteins are then partially digested in the stomach with some carbohydrate digestion.  Fats are not affected.  In the duodenum, bile from the gallbladder emulsifies (breaks up) fats and digestive enzymes from the pancreas attack carbohydrates, proteins and fats.  In the small intestine, remaining parts are further broken down and absorbed into the body.

     

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