Republic of the Philippines
Department of Education
Regional Office IX, Zamboanga Peninsula
8
Z
est forP
rogressZ
eal ofP
artnershipScience 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.
3
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 12
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
https://cutt.ly/7jihYVQ
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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?
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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
https://cutt.ly/ljigphJ
10
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
https://cutt.ly/7jisY4X
11
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
https://cutt.ly/ljisnlC
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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.
Mou th
2.
Esop hagu s
3.
Per istalsis
4.
Stomac h
5.
Prin cipal organ
6.
Small in tes tin e
7.
Large intes tin e
8.
Wat er r eab sorp tio n
9.
Anu s
10.
Exit of so lid w aste
11.
Dig estiv e d isord ers
12.
Ulcer
What’
s N ew
(An sw ers m ay va ry)
Act2 Pa rt A
1.
Brea kin g the cand y in to smaller p ieces
incr ease s the rat e of the foo d's
disso lutio n and chemica l d
iges tio n.
2.
Cru shing the cand y rep res ents the
chewing of fo od -- a for m o f mec hanical
or phy sical dig estio n of fo od .
Part B
1.
M ou th (tee th, to ngu e, s aliva)
2.
The sod a cr ack er is mechan
ically and
chemically dig ested .
What’ s M ore
(An sw ers m ay va ry)
Q1 . Skip pin g main meals
can cau se yo ur metab oli sm
to slow d ow n, w hich can
cau se w eight gain o r mak e
it har der to lo se w eight.
It
can also lead to d iges tives
diso rd ers or disea ses.
Q2 . Eat regu larly
healt hy
foo ds such as hi gh-f iber
foo ds and d rin k 6 to 8
glas ses of wat er d aily.
What I Ha ve L ea rn ed
Act4 Pa rt A
1.
Mou th – es op hagu s – st omac h - small intes tin e – lar ge in tes tin e
– rec tu m
2.
a. 3
b.
6
c. 1
d.
4
e. 2 f.
5 3.
1 . b oth
2 . b oth
3.
bot h
4 . mec hanical
Act 4 P art B
1.
Mou th a. in
gestio n
2.
Esop hagu s
3.
Stomac h b.
dig estio n
4.
Pancr eas
5.
Live r
6.
Gall blad der
7.
Small in tes tin e c. d iges tio n, ab sorp tio n
8.
Large intes tin e d.
abso rp tio n
9.
Rectu m
10.
Anu s e. ex
cret ion
What I Ha ve L ea rn ed
Act 5
1.
gastric juice
2.
chyme
3.
intes tin e
4.
bile 5.
nutrient s
6.
fat s
7.
blo od
8.
was te
9.
large 10.anu s
What I Can Do
(An sw ers m ay va ry)
Asse ssm en t
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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