Lab 10

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Lab 10 Mechanical Digestion (Part II)

• Dr. Kim Wilson

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Introduction Part I (Mechanical Digestion)

• Mechanical digestion physically changes foods
  from large pieces into small minute pieces. This
  process occurs throughout the GI tract along with
  the process of chemical digestion.

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Part A (Dissolving a Life Saver)

• INSTRUCTIONS
• 1. Obtain 2 baby food jars. Label one A, the
  other B. Add 25 cc's warm water to each. (Use the
  same temperature of water in each.)
• 2. Obtain and add one whole life saver to Jar A,
  and at the same time, add one crushed life saver
  to Jar B. Record the time on the Results Sheet.
  Gently swirl each jar once.
• 3. Allow the jars to set undisturbed and observe
  how long it takes each life saver to dissolve.
  Record the results on the Results Sheet.
• 4. Answer related questions on the Questions
  Sheet.

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Part B - Introduction

• Swallowing is a complex process that requires the
  co-ordination of many muscles and other
  structures in the head and neck. The process must
  occur both smoothly and rapidly since respiration
  is inhibited for 1-3 seconds while food clears
  the pharynx.

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Part B Instructions

1. Take 2 or 3 swallows from a glass of water, and
   note the movement of your tongue. In which
   direction does the tongue move each time the
   water is swallowed? Record the results on the
   Results Sheet.
2. Place your fingers gently on your larynx and
   swallow more water. Note its movements. Take a
   firm hold of the larynx and try prevent its
   moving while you swallow. Record the results on
   the Results Sheet.
3. Most acoustical stethoscopes have both diaphragm
   and bell type heads for detecting sounds of
   different frequency. Using both heads, listen for
   swallowing sounds on the front and sides of the
   neck, and over the cardiac sphincter valve as
   your partner swallows more water. The earpieces
   should fit snugly into the ears and enough
   pressure applied to the diaphragm or bell to
   ensure firm contact with the skin. Don't allow
   the stethoscope tubing to touch or rub against
   any firm surface as you listen. This will cause
   noise that will mask the swallowing sounds.
   Record the results on the Results Sheet.
4. Bend from the waist and swallow normally. With
   your partner's help, attempt to drink water from
   a cup (while bending). Record the results on the
   Results Sheet.
5. Answer related questions on the Questions Sheet.

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Part 2 Chemical Digestion

• Chemical digestion begins in the mouth when
  salivary glands are stimulated to secrete saliva.
  Saliva contains an enzyme which aids in the
  digestion of starch.

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Part 2 Instructions

• 1. Chew some paraffin so that you will reflexly
  produce a large amount of saliva. Collect
  approximately 10 cc's of this saliva in a small
  beaker. Using litmus paper, determine the pH of
  the saliva. (Litmus paper turns blue in alkaline
  conditions and red in acid conditions.) Record
  the pH on the Results Sheet.
• 2. Place 5 cc's of a boiled starch suspension
  into each of two test tubes. Label the test
  tubes as 1 and 2.
• 3. Add 1 drop of 2 Tincture of Iodine to each
  test tube. Record the results on the Results
  Sheet.
• Note Starch Iodine Blue/Black Color
• 4. Add 20 drops of saliva to test tube 1. Record
  the time on the Results Sheet.
• 5. Add 20 drops of water to test tube 2. Record
  the time on the Results Sheet.

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Instructions cont.

• 6. Place both of the test tubes in a beaker and
  incubate for 1 hour at 37 C. Record the beginning
  incubation time on the Results Sheet.
• 7. After the 1 hour incubation period, gently
  swirl each test tube and observe for color
  changes. Record these changes on the Results
  Sheet.
• 8. If the suspension in one of the test tubes is
  colorless or lighter in color, proceed to step
  10. If no changes in color have occurred in
  either test tube, proceed to step 9.
• 9. Add 12 more drops of saliva to test tube 1 and
  12 more drops of water to test tube 2. Incubate
  for 30 more minutes. Gently swirl each test tube
  and record the results on the Results Sheet.
• 10.Add 5 cc's of Benedict's solution to each test
  tube and place them in a boiling water bath for 2
  minutes. USE CAUTION TO AVOID INJURY.
• 11.Remove the test tubes from the water bath and
  gently swirl. Observe for any of the following
  color changes

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Results

• - Solution Remains Blue (No Sugar Present)
• Green Solution
• Yellow Solution
• Orange Solution
• Red Solution
• If solution turns green, yellow, orange, or red,
  sugar is present and the amount varies from 1
  (small amount) to 4 (large amount).
• Record the results on the Results Sheet.
• 12.Answer related questions on the Questions
  Sheet.

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Part B Digestion in the Stomach

• 1. Complete the sheet titled, "Student Guide -
  Digestion Biokit Gastric Digestion". Record the
  results in the spaces indicated and include in
  your lab report.
• 2. Answer related questions on the Questions
  Sheet.