Science NineUnit 2—Your Living Body

Science 9-Biology

Worksheet 7-1—Digestion in the Mouth, Esophagus and Stomach -- KEY

Read pages 134-139 of SP to help you answer the following questions:

  1. What is meant by tissue? A group of cells with similar tasks (eg. muscle, nerve, bone)
  2. What is meant by an organ? Several types of tissue grouped together for a specific task. (eg. stomach, heart, liver etc.)
  3. Organs that work together to perform a specific task (like digestion) make up a
    __system__ of the body.
  4. What is saliva? The watery fluid in your mouth. (contains salivary amylase)
  5. Two main body parts that carry out mechanical digestion in the mouth are the _teeth_
    and the tongue
  6. On the diagram, label each part and give it’s function.

  1. Give two reasons why mechanical digestion is important in the mouth:
    1. __food particles must be small enough to fit down the esophagus___
    2. __allows better mixing of food with digestive enzymes______
  2. At the back of your throat there are two separate tubes. They are called the
    ___esophagus______, which carries food to the stomach and the
    _____trachea______which carries air to the lungs.
  3. What is the epiglottis? _a fleshy flap which closes the entrance to the trachea while swallowing______
    What is it’s function? _ closes the entrance to the trachea while swallowing ______
  4. The walls of the esophagus are made up of ___muscle____ tissue.
  5. What material, produced by the esophagus helps lubricate the food so it moves more easily
    through? __mucus______
  6. Describe what happens during peristalsis. A series of muscle contractions that work their way down the esophagus squeeze food down the esophagus.
  7. Do you think food would pass from the throat to the stomach is you were in a no-gravity
    environment? __yes______Explain. It is forced toward the stomach by peristalsis.
  8. Your stomach wall is made up of ___muscle______tissue.
  9. Your stomach can hold up to __2 L___L of food when stretched.

  1. Where exactly is your stomach? Under the ribs on the left side of your body.
  2. Mechanical digestion in your stomach is carried out by the ___contractions___ of muscles in the stomach wall.(kneeding the food)

Material / Function
Pepsin / A digestive enzyme that breaks down protein molecules into amino acids
Hydrochloric acid / Assists the pepsin, making it work better to break down proteins
Mucus / Protective material which coats the walls of the stomach, protecting the lining from the digestive action of pepsin and hydrochloric acid
  1. List the 3 materials present in stomach fluid and state the function of each one:
  2. What actually happens to produce what we call “heartburn”?
    The acidic contents of the stomach are pushed up into the esophagus, producing a burning sensation in the upper chest.
  3. The enzyme pepsin works best when there is _hydrochloric acid_ present in the mixture.
  4. If there was no protective lining of the stomach wall, what would the pepsin and acid do to
    it?___digest it, breaking the protein down into amino acids______
  5. Sometimes the acid and pepsin can get through and cause an area of the stomach wall to be damaged. This causes pain and if left untreated could cause serious damage. This type of
    “sore” on the stomach wall is called a gastric __ulcer______.
  6. Which class (carbohydrates, fats, proteins etc.) of nutrients are broken down by the
    enzymes in the stomach? ___proteins______.
  7. What is located at the “exit” point of the stomach which can close to prevent food from
    passing into the small intestine? _a circle of muscle (sphincter)______
  8. The process of __peristalsis______causes the foods and stomach juices to continually mix in the stomach.

  1. Is the opening at the bottom of the stomach usually open or closed? _closed___
  2. Food from a meal usually remains in the stomach from _2_ to _4_ hours.
  3. Label the following diagram:


Worksheet 7-1—Digestion in the Mouth, Esophagus and StomachPage 1