Republic of the Philippines

Department of Education Regional Office IX, Zamboanga Peninsula

8 Zest for Progress

Zeal of Partnership

Science Grade 8 Quarter 4 - Module 1 The Digestive System

Name of Learner:

Grade & Section:

Name of School:

2

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.

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What’s In

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

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Digestive System

is responsible for the breakdown of can be affected due to

food

which starts from the

imbalance

which may lead to

1.

to the

2.

to the

4.

to the

6.

to the

7.

then

9.

11.

such as

moves food

through

3. 12.

acts as the 5.

is the site for 8.

serves as the 10.

4

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 After 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?

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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.

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.

https://cutt.ly/yjihLsa

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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

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.

Enzymes Where digestion happens

Amylase catalyzes the breakdown of starch into maltose in the mouth and small intestine

Protease, Pepsin catalyze the breakdown of proteins into amino acids in the stomach and small intestine

Lipase catalyzes the breakdown of fats and oils into fatty acids and glycerol in the small intestine

Maltase catalyzes the breakdown of maltose into glucose in the small intestine

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What’s More

Read and Learn More!

AILMENTS DESCRIPTION CAUSE PREVENTION TREATMENT

Gastro-esophageal Reflux (GERD)

Frequent episodes of acid reflux

Muscle found at the end of the esophagus does not close properly, allows acid from the stomach, or leaks into the esophagus.

Avoid alcohol and spicy, fatty, or acidic foods or beverages that trigger heartburn (a burning sensation in the chest)

Medication or by surgery

Peptic Ulcer Open sore in the stomach or duodenum

Tissue eroded by too much stomach acid, acidic juices, smoking, alcohol, and some drugs

Avoid smoking, taking large quantities of tea, coffee, alcohol, and some drugs

Medication

Constipation Difficulty in moving vowel

Not enough water absorbed in the large intestine

Eat plenty of fruits and vegetables, drink plenty of water and move your bowel regularly

Medication

Colon Cancer Malignancy in the area of the colon and rectum

Eating foods that are low in fiber and high in fats and calories

Eat plenty of fruits and vegetables, drink plenty of water and move your bowel regularly

Surgery Radiation therapy or Chemotherapy

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

Avoid eating foods with a high saturated fat content

Gall bladder removal

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.

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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?

9

What I Have Learned

Activity 4

Part A. Complete the Digestive System Worksheet

17

1. Complete the flow chart to show the digestive system.

2. Order the stages of digestion from numbers 1 to 6.

a. ______ The food is mixed with gastric juices in the stomach.

b. ______ The feces are expelled through the rectum.

c. ______ In the mouth, the teeth crush the food, and it is mixed with saliva.

d. ______ 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)

large intestine rectum mouth small intestine

stomach esophagus

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Activity 4

Part B. Let’s label it!

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.

▪ 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

the stomach, it is churned with lots of acids.

1 a

2

3 b

4

5

6

8 d 7

c

9

10

14

e

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Activity 5: Complete the Digestive System Worksheet

10

Use the words in the box to complete the spaces in the text.

The stomach contains acid called

juices. Muscles contract to mix food with this acid.

This makes a thick liquid called .

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.

fats

bile

nutrients

chyme

large

blood

gastric

waste

anus

intestine

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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 DINNER

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

Sunday

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Assessment

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 C. Produces bile

B. Partially digest starch 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

10

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Additional Activity

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

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15

Answer Key Grade 8 Q4 W1 Science

What’s In

1.Mouth

2.Esophagus

3.Peristalsis

4.Stomach

5.Principal organ

6.Small intestine

7.Large intestine

8.Water reabsorption

9.Anus

10.Exit of solid waste

11.Digestive disorders

12.Ulcer

What’s New

(Answers may vary)

Act2 Part A

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’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.

Q2. Eat regularly healthy

foods such as high-fiber

foods and drink 6 to 8

glasses of water daily.

What I Have Learned

Act4 Part A

1.Mouth – esophagus – stomach - small intestine – large intestine

– rectum

2.a. 3

b. 6

c. 1

d. 4

e. 2

f. 5

3. 1. both

2. both

3. both

4. mechanical

Act4 Part B

1.Mouth a. ingestion

2.Esophagus

3.Stomach b. digestion

4.Pancreas

5.Liver

6.Gall bladder

7.Small intestine c. digestion, absorption

8.Large intestine d. absorption

9.Rectum

10.Anus e. excretion

What I Have Learned

Act 5

1.gastric juice

2.chyme

3.intestine

4.bile

5.nutrients

6.fats

7.blood

8.waste

9.large

10.anus

What I Can Do

(Answers may vary)

Assessment

1.C

2.C

3.B

4.C

5.A

6.C

7.B

8.D

9.D

10.C

16

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 Region IX Hymn

Writer: NEIL FE M. CAMPOS

Teacher 3 Zamboanga del Sur NHS

Editor: LEE G. BARAQUIA, Ed.D.

Master Teacher 1

Zamboanga del Sur NHS

Reviewer: 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

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