Download Digestion Lab - Pearland ISD

DIGESTION SIMULATION LAB
PAP CLASS SET
BACKGROUND INFORMATION
What is digestion and where does it begin?
Digestion is the breaking down of food into forms that our bodies can use. Your digestive
system is responsible for converting the food we eat into energy for our bodies to use.
Digestion begins when you put food in your mouth and begin to chew. Your teeth help to
break the food apart, saliva helps to soften the food and your tongue helps to push the food
into your throat when you’re ready to swallow. When we swallow the food goes into a tube
called the esophagus. The muscles that surround the esophagus help to squeeze and push the
food into the stomach.
The stomach is a sack that receives the food from the esophagus. Your stomach is located just
below the heart. The stomach makes digestive juices (acids and enzymes) that help to break
our food down into a thick liquid or paste. Your stomach is a muscular organ that is able to
move in order to mix the food with digestive juices. Food usually remains in the stomach for
about two hours.
What is the major site of digestion?
What is the major site of digestion? If you answered stomach, you missed it! The correct
answer is small intestine.
Imagine a water hose 1 inch in diameter and 20 feet long. This is the overall size of your small
intestine. Most digestion occurs in the first 10 inches, the remaining length is used for
absorbing nutrients.
Food is squirted into the small intestine through a valve connecting it to the stomach. Small
quantities of semi-fluid, approximately 1 teaspoon per minute, are released into the small
intestine and combine with fluids from the pancreas and gall bladder.
The pancreas secretes fluids to neutralize the stomach acid and carry enzymes for digesting
proteins, fats, sugars, and starches. Some proteins and starches are digested earlier in the
stomach. Others are digested in the small intestine. The brain tells the body how much
enzyme of each type to secrete into the small intestine.
The gall bladder secretes bile into the first 10 inches of the small intestine. Bile works like a
detergent to break fat globules into smaller droplets for digestion. The enzymes in the
pancreatic fluid can now surround these droplets and begin the digestive process.
Digested food is absorbed into the walls of the small intestine as it moves through the
intestine. The undigested food is not absorbed. It moves through the next part of the
digestive system, the large intestine. The large intestine is about five feet long so it is shorter
than the small intestine. The large intestine is however thicker or wider than the small
intestine and that is why it is called the large intestine. The undigested food enters the large
intestine as a liquid paste. In the large intestine water is removed from the liquid paste turning
what is left into solid waste. The solid waste then collects in the rectum at the end of the large
intestine and will finally leave the body through an opening called the anus.
What causes our stomach to growl?
Stomach growling occurs when the stomach receives signals from your brain to begin
digestion but the stomach is empty. Your brain might sense you're running low on energy
(glucose) or even seeing or smelling something you want to eat can get things going. The
motion of the stomach muscles begins, but the organ is hollow. The movement of the muscles
mixing the acids of the stomach in the hollow space of the stomach produces vibrations we
hear as growling, or rumbling, or gurgling. The obvious solution is to eat, but this is not
always practical. Because your body responds to things that you do daily, people who eat on
very regular schedules may be more susceptible to this problem.
INTESTINE DIGESTION LAB
Procedure:
1. Add 25 mL of vinegar to a plastic bag. Color the vinegar by adding 3 drops of
coloring.
food
2. Measure 25 mL of oil. Pour the oil into the bag containing colored vinegar. This mixture
represents undigested food leaving the stomach and entering the small intestine. Observe
the bag. Write your observations below.
3. After you complete your observation in step #2, add 25 mL of baking soda solution to the
vinegar and oil. Seal the bag. The baking soda solution represents fluid from the pancreas
that is added to food entering the small intestine. The fluid contains enzymes for digestion
which also neutralizes the acid as it leaves the stomach. Record what is happening to the
acid.
4. Observe the contents of the bag. Mix the contents, and observe the contents again. What
do you see? Did anything change? Explain what you see below.
5. Bile is produced by the liver and stored in the gall bladder. It is secreted into the small
intestine to break large droplets of fat molecules into smaller ones. This increases the surface
area where fat-digesting enzymes work. Bile works like detergent on food entering the small
intestine. What do you think the detergent will do?
6. Measure 10 mL of detergent in a graduated cylinder. Add the detergent to the bag. Seal
and mix the contents of the bag. Observe how the detergent (bile) affects the oil. Record
what you see happen to the oil.
NAME: _____________________________________ DATE:_________PERIOD:________PAP Digestion Lab
Questions: Use the information in the Background Information passage.
1. What is digestion? _________________________________________________________________
__________________________________________________________________________________________
2. What is the body’s major site of digestion? ______________________________________________
3. Where does most of the digestion occur in the small intestine? _____________________________
4. What is the remaining length of the small intestine used for? _______________________________
5. What is the function of the pancreas? __________________________________________________
__________________________________________________________________________________________
6. Why are enzymes needed for digestion? ________________________________________________
__________________________________________________________________________________________
7. Which organ secretes bile? _________________________________________________
8. What is the function of bile? _________________________________________________________
9. Where does the undigested food move after it leaves the small intestine? _____________________
10. What is the function of the large intestine? ______________________________________________
__________________________________________________________________________________________
11. What 2 systems are interacting when your stomach “growls”? _________________ &_________________
MULTIPLE CHOICE QUESTIONS:
_____12. The main function of the human digestive system is to
A. break down foods for absorption into blood
B. exchange oxygen and carbon dioxide in the lungs
C. release energy from sugars within the cells
D. carry nutrients to all parts of the body
_____13. Which type of digestion occurs in the mouth when an individual chews a piece of bread?
A. mechanical digestion only
B. chemical digestion only
C. both mechanical and chemical digestion
D. neither mechanical nor chemical digestion
_____14. If too much water is removed from undigested food, the feces
hardens and constipation occurs. This malfunction affects which part of the
digestive system?
A.
B.
C.
D.
F
G
C
E
_____15. In the human digestive system, most nutrients are absorbed into the blood through the lining of the
A. esophagus
B. stomach
C. large intestine
D. small intestine
_____16. Into which parts of the human digestive system are digestive enzymes secreted?
A. mouth, esophagus, stomach
B. stomach, small intestine, large intestine
C. mouth, stomach, small intestine
D. esophagus, stomach, large intestine
_____17. The removal of a human gallbladder interferes most directly with the
A. production of gastric juices
B. production of saliva
C. storage of pancreatic juices
D. storage of bile
_____18. Nutrients from digested food enter the blood stream through the process of
A. absorption
B. elimination
C. respiration
D. secretion
_____19. Fats are important nutrients because they
A. provide genetic information
B. contain stored energy
C. are used in photosynthesis
D. maintain bone density
_____ 20. In which human organ would the chemical digestion of a piece of meat normally begin?
A. oral cavity
B. small intestine
C. stomach
D. liver
The diagram below shows several organs in the human digestive system.
Explain two ways that food is changed as it passes through the digestive system.
(21) ______________________________________________________________________________________________
(22) ______________________________________________________________________________________________