Grade 8 Digestive System

1. Welcome
Grade8STE
andSPJ
Students!

2. About the teacher:
Hi everyone! I’m Ms. Charlene N. Llagas.
I’m currently taking up Bachelor of
Secondary Education Major in Science.
I live in Talusan, Balingasag, Misamis
Oriental.
My hobbies are singing, reading, and
watching movies and Korean Dramas.

3. CLASSROOM RULES:
● Be on time. Don't be late for class.
● Always ask permission if you want to go out. (Hand signal -
to not distract the class)
● Always keep your study area clean and free of anything
unrelated to our subject.
● Treat other people with respect. May it be your teachers,
classmates and everyone around you.
● Keep your gadgets unless you’re required to use it.
● Always come prepared.

4. Happy
1
Sad
2
TEMPERATURE CHECK
Sleepy
Angry/
Grumpy
3 4

5. Digestive
System:
Structuresand
Functions
8thgrade

6. - Food plays a central role in the
survival of species. Food gives
organisms energy that enables
them to carry out the many
activities they do each day; this
includes predators chasing a prey
or prey escaping a predator,
arboreal organisms climbing trees
to gather fruits, or fish swimming in
schools in search for food, to name
a few. Organisms are able to obtain
energy from the foods they eat
through digestion.

7. How do we digest
food?
Digestion of food is carried out
by the organs and substances of
the digestive system. During
digestion, food is broken down
to smaller parts -- a fraction of
which is made up of nutrients.
These nutrients are circulated to
the different parts of the body
through the bloodstream and
assimilated by cells.

8. Almost all animals have a digestive system in which food enters the
mouth, is moved through a long tube, and exits the anus as feces.
In humans, digestion starts
in the mouth where food is
chewed and broken down to
smaller pieces for easier
digestion. This is called
mechanical digestion.

9. Initial chemical digestion starts
also in the mouth. This is carried out
by enzymes -- molecules that speed
up chemical reactions. Enzymes
present in saliva such as amylase
helps break down carbohydrates,
which are large complex molecules,
into simpler ones that can be used
by the body.

12. Six Functions ofthe
Digestive System:
1. Ingestion
2. Mechanical
processing
3. Digestion
4. Secretion
5. Absorption
6. Excretion

13. Ingestion
- The process of taking in food through the
mouth. In vertebrates, the teeth, saliva, and
tongue play important roles in mastication
(preparing the food into bolus). While the food
is being mechanically broken down, the
enzymes in saliva begin to chemically process
the food as well.
Mechanical Processing
- Crushing and shearing
- Makes materials easier to propel along
digestive tract

14. Digestion
- The process that converts nutrients in ingested
food into forms that can be absorbed by the
gastrointestinal tract. Proper digestion requires
both mechanical and chemical digestion and
occurs in the oral cavity, stomach, and small
intestine.
Secretion
- Is the release of water, acids, enzymes, buffers,
and salts
- By epithelium of digestive tract
- By glandular organs

15. Absorption
- The process by which the products of digestion
are absorbed by the blood to be supplied to the
rest of the body. During absorption, the
digested products are transported into the
blood or lymph through the mucous membrane.
Excretion
- Removal of waste products from body fluids
- Process called defecation removes feces

16. 2typesofDigestiveSystem
● CompleteDigestive System
● IncompleteDigestiveSystem

17. - Almost all animals have a tubelike digestive
system; one end of the tube serves as the
mouth while the other end serves as the
anus. This digestive system is called a
Complete Digestive System. Food enters
the mouth, passes through the long tube, and
exits as feces through the anus.
- The smooth muscles of the tubelike digestive
organs move the food rhythmically through
the system where it is broken down into
absorbable forms. Outside of this tube are
attached some accessory organs -- the liver,
gallbladder, and pancreas -- which also help
in the digestion of food.

18. Cyclostomes - jawless fishes
Gar - one of the largest of all
freshwater fishes.

19. Necturus - aquatic salamanders

20. The more primitive animals
like the Hydra have a
‘digestive system’ with only
one opening which is also
called an Incomplete
Digestive System. These
organisms eat and defecate
with their mouth which also
alternates as their anus.

21. Let’sTestYourKnowledge!

22. 1. _______ is the breaking, crushing,
and mashing of food.
a. Mechanical digestion
b.Chemical digestion
c. Both a and b
d.None of the above

23. 2. It is the physical breaking down
of the food in the mouth.
a. Chewing
b.Pitting
c. Chewing
d.Gargling

24. 3. _______ is a chemical that the
body uses to break down large
molecules into small ones.
a. Hormone
b.Enzyme
c. Juice
d.Water

25. 4. What does the Gallbladder
store?
a. Bile
b.Fat
c. Carbohydrates
d.Insulin

26. 5. The _______ is the last part of the
large intestine that stores the feces
until they are expelled out.
a. Anus
b.Liver
c. Pancreas
d.Rectum

27. 6. Teeth are very important organs
for chemical digestion.
True or False?
7. Mechanical processing is the
crushing and shearing of food.
True or False?

28. 8. One end of the tube serves as the
mouth while the other end serves as
the anus. This digestive system is
called a Complete Digestive System
True or False?

29. 9. Hydra is an example of an organism
that has Incomplete Digestive System
True or False?
10. Secretion is the removal of waste
products from body fluids.
True or False?

30. 11. The _______ produces bile, which
helps in the digestion of fat in the
small intestine.
12. _______ occurs when materials
enter the digestive tract via the
mouth.

31. 13. _______ are present in saliva such
as amylase that helps to break down
carbohydrates.
14. Organisms are able to obtain
_______ from the foods they eat
through digestion.

32. 15. During ________, food is broken
down to smaller parts -- a fraction of
which is made up of nutrients.

33. ANSWER KEY:
1. A 6. False 11. Liver
2. C 7. True 12. Ingestion
3. B 8. True 13. Enzymes
4. A 9. True 14. Energy
5. D 10. False 15. Digestion