Republic of the Philippines
Department of Education
Regional Office IX, Zamboanga Peninsula
8
Z est for Progress
Z P
eal of
Science Grade 8
Quarter 4 - Module 1
The Digestive System
Name of Learner:
Grade & Section:
Name of School:
artnership
Module
1
The Digestive System
What I Need to Know
This module was designed and written with you in mind. It is here to
help you master the concepts behind the Digestive System (S8LT-IVa-13).
The scope of this module permits it to be used in many different learning
situations. The language used recognizes the diverse vocabulary level of
students. The lessons are arranged to follow the standard sequence of the
course. But the order in which you read them can be changed to correspond
with the textbook you are now using.
After going through this module, you are expected to:
1. describe how the upper and lower gastrointestinal tracts work
2. explain ingestion, absorption, assimilation, and excretion; and
3. identify common ailments of the digestive system.
The digestive system is truly astonishing. It takes the foods we eat and
breaks them into smaller components that our bodies can utilize for energy,
cell repair, and growth. This lesson presents the main parts of the digestive
system and how they interact.
The easiest way to understand the digestive system gastrointestinal (GI)
is to divide its organs into two main categories. The first group is the organs
that make up the alimentary canal. These organs are part of the "tube" our
food travels through from the mouth to the anus. Accessory digestive organs
comprise the second group. Food never enters or passes through these
organs, but they are significant for orchestrating food breakdown. Accessory
digestive organs, despite their name, are significant to the function of the
digestive system.
2
What’s In
12
Activity 1: Concept Map
Using the words/phrases from the word box below, complete the concept map on
the Digestive System.
anus
small intestine
esophagus
peristalsis
stomach
large intestine
mouth
water reabsorption
ulcer
digestive disorders
principal organ
exit of solid waste
Digestive System
is responsible for the breakdown of
can be affected due to
food
imbalance
which starts from
the
which may lead to
1.
11.
to the
2.
such as
moves
food
through
3.
acts as
the
5.
is the
site for
8.
serves
as the
10.
12.
to the
4.
to the
6.
to the
7.
then
9.
3
What’s New
Activity 2
Part A. A Sweet Break
Objectives:
After performing this activity, you should be able to:
1. describe the process of mechanical digestion; and
2. explain how the physical breaking down of food helps in its digestion.
Materials Needed:
two 100 mL beakers or clear containers
warm water
two pieces of candies (hard candies)
mortar and pestle
paper towel
Procedure:
1. Fill the two beakers with warm water. See to it that the amount of water
placed in each glass is about similar. And then label the glasses A and B.
2. Prepare two pieces of candies. Wrap a piece of candy in a paper towel and
crush it using a mortar and pestle or any hard object like a piece of wood.
3. Place one piece of candy into the glass of warm water labeled A and put the
crushed piece of candy in the remaining glass of warm water labeled B.
4. Observe how long it takes for the whole candy in Glass A and the crushed
piece of candy in Glass B to dissolve.
Q1. How does crushing the candy to smaller pieces affect its dissolution?
Q2. What does crushing the candy represent in the process of digestion?
Part B. How Does It Taste?
Have a piece of a soda cracker. Chew it for about three (3) minutes before
you swallow it. Observe the changes the soda cracker will undergo as you
mechanically and chemically digest it. Record your observation in the table below.
Food Item
Taste of the Food
Before Chewing
Soda Cracker/Biscuit
1. What organs are involved in
chewing the soda cracker?
2. What
do
you
think
happened to the soda
cracker in your mouth?
4
After Chewing
What is it
Digestion is the breakdown of large food particles into smaller and
absorbable nutrients needed for energy production, growth, and cellular repair. It
begins with ingestion through the mouth and ends with defecation or excretion.
Digestion takes place in the
gastrointestinal tract in two main
forms: mechanical and chemical.
Mechanical digestion is the physical
degradation of large food particles into
smaller pieces that digestive enzymes
can
access
through
chemical
digestion.
Chemical digestion is the
enzymatic cleavage of proteins,
carbohydrates, and fats into tiny
amino acids, sugars, and fatty acids.
Once food enters the mouth, it
mixes with saliva and gets chewed
through the process of mastication.
Saliva is rich in mucus and salivary
enzymes such as amylase, which
helps break down carbohydrates. And
together,
with
the
effects
of
mastication, it creates a mass called a
food bolus. The food bolus then travels
down the esophagus via wave-like
muscular
contractions,
called
peristalsis, before it reaches the
stomach.
https://cutt.ly/yjihLsa
At certain instances, you hear your stomach rumbling. This is the sound
you hear as the gastric juices are churned in an empty stomach. This indicates
that you are already hungry, and it is time for you to eat. The stomach and some
glands start to produce gastric juices to prepare your stomach for the food you
will eat. These gastric juices provide an acidic environment in the stomach.
5
Enzymes
Amylase
Protease, Pepsin
Lipase
Maltase
Where digestion happens
catalyzes the breakdown of starch into maltose in the
mouth and small intestine
catalyze the breakdown of proteins into amino acids
in the stomach and small intestine
catalyzes the breakdown of fats and oils into fatty
acids and glycerol in the small intestine
catalyzes the breakdown of maltose into glucose in the
small intestine
The pancreas is located below the stomach. It secretes a mix of enzymes
that together are called pancreatic juice, which helps neutralize the very acidic
chyme when it enters the small intestine. Pancreatic juice also allows us to digest
proteins, fats, and carbohydrates.
The liver digests food by producing bile to break down fats, removing toxins,
and breaking down and storing some vitamins and minerals. The gall bladder
stores the bile that is produced by the liver. When needed, bile passes into the
small intestine, where it breaks down fat.
Digestion ends in the small intestine, where
nutrients are absorbed in the small intestine's villi, tiny
finger-like processes. Villi contain capillary beds, as well
as lymphatic vessels called lacteals. Fatty acids absorbed
from broken-down chyme passes into the lacteals.
Capillaries absorb glucose, fructose, and galactose,
transported to all cells of the body.
As they passed through the alimentary canal (gut),
digested and undigested foods have different outcomes
https://cutt.ly/7jihYVQ
Assimilation is the movement of digested food
molecules into the cells of the body where they are used. For
example:
• glucose is used in the process of respiration to provide energy
• amino acids are used to build new proteins
Wastes that remain after digestion go to the large intestine, where water is
also reabsorbed. These wastes, including the water that was not reabsorbed, are
temporarily stored in the rectum before they are excreted out of the body through
the anus. Egestion or excretion happens when these feces pass out of the body
through the anus.
6
What’s More
Read and Learn More!
Different organs in the digestive system work together to make
digestion possible. If any of these organs are not in good condition, the
whole system cannot function properly.
Taking the best care of the digestive system can support the
prevention of ailments. Peptic ulcer, constipation, and other ailments
could be avoided if the digestive system is healthy. That is why
practicing health habits is essential to enable your digestive system to
work well. However, many people have habits that, sometimes not
known to them, can cause digestive system illnesses.
"An Ounce of Prevention is Worth a Pound of Cure." Therefore, you
need to learn about some common ailments that may affect parts of
your digestive system and how they can be prevented. Some common
ailments of the digestive system are in the chart below.
AILMENTS
Gastroesophageal
Reflux (GERD)
DESCRIPTION
Frequent
episodes of acid
reflux
CAUSE
Muscle found at the
end of the esophagus
does not close
properly, allows acid
from the stomach, or
leaks into the
esophagus.
Tissue eroded by too
much stomach acid,
acidic juices, smoking,
alcohol, and some
drugs
Not enough water
absorbed in the large
intestine
Peptic Ulcer
Open sore in
the stomach or
duodenum
Constipation
Difficulty in
moving vowel
Colon Cancer
Malignancy in
the area of the
colon and
rectum
Eating foods that are
low in fiber and high in
fats and calories
Acute
cholecystitis
Gallstones in
the gall bladder.
Severe, steady
pain in the
upper abdomen
Collections of solid
material predominantly
crystals of cholesterol
in the gallbladder
7
PREVENTION
Avoid alcohol and
spicy, fatty, or acidic
foods or beverages
that trigger heartburn
(a burning sensation
in the chest)
TREATMENT
Medication or
by surgery
Avoid smoking, taking
large quantities of tea,
coffee, alcohol, and
some drugs
Medication
Eat plenty of fruits
and vegetables, drink
plenty of water and
move your bowel
regularly
Eat plenty of fruits
and vegetables, drink
plenty of water and
move your bowel
regularly
Avoid eating foods
with a high saturated
fat content
Medication
Surgery
Radiation
therapy or
Chemotherapy
Gall bladder
removal
The way the digestive system work has something to do with your health.
To keep it healthy and work smoothly, you need to know what you can do to take
care of your digestive system.
Learn to practice these habits:
▪
Have a balanced diet every day. The food that you eat should contain the
right amount of the different nutrients needed by the body. Nutrients are
chemical substances that you eat and drink to grow and become healthy.
These include vitamins and minerals, vegetables and fruits, meat and fish
products, cereals, and other carbohydrates.
▪
Eat regularly and observe the proper time for eating. When buying ready
to eat foods, be sure they come from covered containers. Bacteria or germs
and harmful insects easily contaminate uncovered foods.
▪
Chew the food slowly and well. Relax while eating your meals. Do not
swallow large chunks of food.
▪
Do not eat when you are angry, sad, or tense. The food you take in will not
be properly digested and may cause indigestion.
▪
Wash uncooked foods thoroughly before eating them.
▪
Drink about six to eight glasses of water a day. Lessen your intake of
sweets during snacks. Chocolates, cakes, and candies may destroy your
appetite.
▪
Take part in a cheerful and relaxing conversation. It will help stimulate
intestinal activity.
Q1. Why is it dangerous to skip the main meal? How does it affect the body?
Q2. How can we keep our digestive system healthy? What kind of food should we
eat and what should we avoid?
8
What I Have Learned
17
Activity 4
Part A. Complete the Digestive System Worksheet
1. Complete the flow chart to show the digestive system.
large intestine
rectum
stomach
mouth
esophagus
small intestine
2. Order the stages of digestion from numbers 1 to 6.
a.
b.
c.
d.
______
______
______
______
The food is mixed with gastric juices in the stomach.
The feces are expelled through the rectum.
In the mouth, the teeth crush the food, and it is mixed with saliva.
In the small intestine, the food mixes with bile from the liver and
the nutrients and vitamins are absorbed.
e. ______ The food passes down the esophagus and into the stomach.
f. ______ The remains of the food are transformed into feces in the large
intestine.
3. Label with what form of digestion occurs in each part.
(Mechanical, Chemical, or Both)
https://cutt.ly/ljigphJ
9
Activity 4
Part B. Let’s label it!
14
Directions: Label the Digestive System with different parts found in
the Word Bank below. Write your answer in the box numbered 1 to
10. Label the different parts with the process/es that occur (ingestion,
digestion, absorption, and excretion). Write your answer in the box with letters
a to e. Choose the best answer that best describes every part of the
illustration.
1
a
2
5
b
3
6
4
8
7
d
c
9
10
e
https://cutt.ly/7jisY4X
Anus - the opening at the end of the digestive system from which feces (poo) leaves the body
Esophagus - the long tube between the mouth and the stomach
Gall bladder - a small sac below the liver which stores and releases bile into the small intestine
Large intestine - the shorter, wider tube that follows the small intestine
Liver - a large organ that makes bile that neutralizes stomach acid.
Mouth - the first part of the digestive system, where food enters the body
Pancreas – a gland below the stomach that makes lots of chemicals called enzymes that help
break down food.
▪ Rectum - the lower part of the large intestine, where feces (poo) is stored before it leaves the
body
▪ Small intestine - the long, thin winding tube that food goes through after it leaves the
stomach
▪ Stomach - a sack-like, muscular organ that is attached to the esophagus. When food enters
10
the stomach, it is churned with lots of acids.
▪
▪
▪
▪
▪
▪
▪
Activity 5: Complete the Digestive System Worksheet
10
https://cutt.ly/ljisnlC
Use the words in the box to complete the spaces in the text.
fats
bile
The stomach contains acid called
juices. Muscles contract to mix food with this acid.
This makes a thick liquid called
.
nutrients
chyme
large
blood
gastric
waste
anus
intestine
Chyme from the stomach passes into the small
. Here, the chyme mixes with a
liquid from the liver called
and pancreatic
juices from the pancreas. These liquids break the
chyme into
:
proteins,
carbohydrates,
,
vitamins
and
minerals can now pass through the wall of the small
intestine and into the
.
Any food left in the small intestine is now
.
This material passes into the
intestine where any extra water is absorbed into the
blood. Dry waste passes into the rectum and waits to
leave the body through the
.
▪
An adult’s digestive system is approximately 9 meters long.
▪
Food usually takes between 24 and 72 hours to pass from
your mouth to the toilet.
▪
Your small intestine begins digesting your food about 30
minutes after eating.
11
What I Can Do
Activity 6: My Eating Habit
Adolescence is characterized by several major changes and development
in the body. To reach its full potential, the body needs the right kind and
amount of nutrients through healthy eating habits.
A. Fibers in cereals, fruits, and vegetables clean the intestines. They
help prevent constipation.
Write the fiber foods that you eat in one day. Fill in the table below.
BREAKFAST
LUNCH
DINNER
B. Eat your meals regularly. Eating on time helps prevent hyperacidity
and indigestion.
Write the time you eat your meals each day. Fill in the table below.
DAYS
BREAKFAST
LUNCH
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
12
DINNER
Assessment
10
Directions: Encircle the letter of the best answer.
1. Which of the following sequences correctly traces the passage of food through
the human digestive tract?
A. Esophagus, pharynx, stomach, large intestines, large intestine
B. Esophagus, stomach, small intestines, large intestines, pharynx
C. Pharynx, esophagus, stomach, small intestines, large intestines
D. Pharynx, stomach, esophagus, small intestines, large intestines
2. Which of the following refers to the process wherein large food molecules are
broken down into soluble and diffusible molecules that can be absorbed into
the body cells?
A. Absorption
B. Assimilation
C. Digestion
D. Ingestion
3. What do you call the wave-like contraction that transports food along the
digestive tract?
A. Absorption
B. Peristalsis
C. Swallowing
D. Vomiting
4. Final and complete digestion happens in the
.
A. Large intestine
B. Rectum
C. Small intestine
D. Stomach
5. The enzyme in the saliva that helps digest food is called
A. Amylase
B. Lipase
C. Pepsin
.
D. Starch
6. Saliva does the following EXCEPT
A. Aids in swallowing
B. Partially digest starch
.
C. Produces bile
D. Softens food
7. A muscular sac located on the posterior surface of the liver that stores and
concentrates bile.
A. Epiglottis
B. Gall bladder
C. Liver
D. Pancreas
8. What do you call the tiny finger-like processes of the small intestine that serve in
the absorption of nutrients?
A. Epiglottis
B. Gall bladder
C. Pancreas
D. Villi
9. What is the major function of the large intestine?
A. Breakdown of fats
C. Ingestion
B. Defecation
D. Water reabsorption
10. Which of the following is NOT an accessory organ of the digestive system?
A. Liver
B. Pancreas
C. Pharynx
D. Salivary glands
13
Additional Activity
20
Activity 6: Let’s add more!
Direction: Make an eye-catching poster that will show at least three healthful
practices that will maintain the normal functioning of your digestive system.
Use short bond paper for your output.
Standards: Your output/product will be assessed based on the following
criteria:
1. Accuracy of content
2. Organization of idea
3. Clarity of message
4. Creativity
14
15
What’s In
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
What’s New
(Answers may vary)
Act2 Part A
Mouth
Esophagus
Peristalsis
Stomach
Principal organ
Small intestine
Large intestine
Water reabsorption
Anus
Exit of solid waste
Digestive disorders
Ulcer
1. Breaking the candy into smaller pieces
increases the rate of the food's
dissolution and chemical digestion.
2. Crushing the candy represents the
chewing of food -- a form of mechanical
or physical digestion of food.
Part B
1.
Mouth (teeth, tongue, saliva)
2. The soda cracker is mechanically and
chemically digested.
What I Have Learned
Act4 Part A
What’s More
(Answers may vary)
Q1. Skipping main meals
can cause your metabolism
to slow down, which can
cause weight gain or make
it harder to lose weight. It
can also lead to digestives
disorders or diseases.
1. Mouth – esophagus – stomach - small intestine – large intestine
– rectum
2. a. 3
b. 6
c. 1
d. 4
e. 2
Q2. Eat regularly healthy
foods such as high-fiber
foods and drink 6 to 8
glasses of water daily.
f. 5
3. 1. both
2. both
3. both
4. mechanical
Act4 Part B
1. Mouth
2. Esophagus
3. Stomach
4. Pancreas
5. Liver
6. Gall bladder
7. Small intestine
8. Large intestine
9. Rectum
10. Anus
What I Have Learned
Act 5
a. ingestion
b. digestion
c. digestion, absorption
d. absorption
e. excretion
Assessment
1. C
1. gastric juice
2. chyme
3. intestine
4. bile
5. nutrients
6. fats
7. blood
8. waste
9. large
10. anus
2. C
3. B
4. C
5. A
6. C
7. B
8. D
9. D
10. C
What I Can Do
(Answers may vary)
Answer Key Grade 8 Q4 W1 Science
References
Books:
Campo, Pia C., May R. Chavez, Maria Helen D. H. Catalan, Leticia V. Catris, Marlene B.
Ferido, Ian Kendrich C. Fontanilla, Jacqeline Rose M. Gutierrez, Shirley R. Jusayan,
Michael Anthony B. Mantala, Cerilina M. Maramag, Marie Paz E. Morales, Eligio C.
Obille, Jr., Digna Paningbatan, Genevieve Faye Pasamonte, Ma. Dulcelina O.
Sebastian, Rolando M. Tan, and Rodolfo S. Treyes. "Unit 4 Module 3 The Digestive
System." In Science - Grade 8 Learner's Module, First Edition, 291-305. Pasig City,
Philippines: Department of Education, 2013.
Madriaga, Estrellita A., Meliza P. Valdoz, Marites D. Aquino, Mary Anne B. Castillo, and
Gil Nonato C. Santos. "Unit 12 Structure and Functions: Digestive System." In
Science Links 8 Worktext for Scientific and Technological Literacy, 314-336. Manila,
Philippines: Rex Book Store, Inc., 2015.
Pavico, Josefina Ma. F., Anna Cherylle M. Ramos, Aristea V. Bayquen, Angelina A. Silverio,
and John Donnie A. Ramos. "Chapter 12 Food Trip." In Exploring Life Through
Science Series The New Grade 8, Second Edition. 245-263. Quezon City, Philippines:
Phoenix Publishing House, Inc., 2017.
Electronic Resources:
Rmr09. (n.d.). Label the digestive system. Retrieved December 30, 2020, from
https://www.tes.com/teaching-resource/label-the-digestive-system-6109934
Digestive system gap fill worksheet. (n.d.). Retrieved December 30, 2020, from
https://www.liveworksheets.com/md31237tv
Keeping the Digestive System Healthy. (2011, March 22). Retrieved December 30, 2020,
from https://lrmds.deped.gov.ph/detail/16
Development Team
Writer:
Editor:
Reviewer:
NEIL FE M. CAMPOS
Teacher 3
Zamboanga del Sur NHS
LEE G. BARAQUIA, Ed.D.
Master Teacher 1
Zamboanga del Sur NHS
MILA P. ARAO
EPS - Science
Management Team:
DANNY B. CORDOVA, Ed.D., CESO VI
Schools Division Superintendent
MARIA COLLEEN L. EMORICHA, Ed.D, CESE
Assistant Schools Division Superintendent
MARIA DIOSA Z. PERALTA
CID Chief
MA. MADELENE P. MITUDA, Ed.D.
Education Program Supervisor – LRMDS
MILA P. ARAO
Education Program Supervisor - Science
Region IX Hymn
OUR EDEN LAND
Here the trees and
flowers bloom,
Here the breezes
gently blow,
Here the birds sing
merrily,
And liberty forever
stays,
Golden beams of
sunrise and sunset,
Are visions you’ll never
forget.
Oh! That’s Region IX...
Hardworking people
abound,
Every valley and dale
Zamboangenos,
Here the Badjaos
Tagalogs, Bicolanos,
swam the seas,
Cebuanos, Ilocanos,
Here the Samals live in
Subanens, Boholanos,
peace,
Illongos,
Here the Tausogs
All of them are proud
thrive so free,
and true
With the Yakans in
Region IX our Eden
unity.
Land.
Gallant men And
Ladies fair,
Linger with love and Region IX, our Eden
Land.
care,
16