DIGESTIVE SYSTEM; HUMAN DIGESTIVE SYSTEM; SCIENCE; BIOLOGY; DIGESTION

1. THE HUMAN DIGESTIVE
SYSTEM
GRADE 8
SIR AARON RAFAEL RANOIS F. SAN JOSE

2. QUESTION
WHAT HAPPENS TO
THE FOOD ONCE
DIGESTED?

3. QUESTION
HOW LONG
DOES IT TAKE
TO DIGEST
FOOD?

4. THREE MAIN FUNCTIONS
1. Ingestion of food
2. Breakdown of food for cell absorption
3. Eliminating undigested
materials

5. DIGESTIVE SYSTEM
It is composed of
different organs
cooperating for food
digestion.

6. TYPES OF DIGESTIVE ORGANS
1. Accessory organs – assist in food
digestion. (salivary glands, liver,
gallbladder, pancreas)
2. Alimentary canal – contains organs where
food passes through (mouth, pharynx,
esophagus, stomach, small and large
intestines, rectum, anus)

7. QUESTION
WHERE DOES
DIGESTION BEGIN?

8. A. THE ORAL CAVITY
Ingestion is the process from
which the body take in the food through
the mouth for digestion, absorption and
elimination.

9. A. THE ORAL CAVITY
The mouth or oral cavity is the first
portion of the digestive tract or
alimentary canal.

10. TYPES OF DIGESTION
1. Chemical – involves the action of
enzymes and other chemical
substances in the body
2. Mechanical – involves the cutting,
crushing or grinding of food using the
teeth (mastication)

11. EXTERNAL TOOTH DIVISION
1. Crown
2. Neck
3. Root

12. INTERNAL TOOTH DIVISION
1. Enamel
2. Dentin
3. Pulp
4. Cementum

13. FOUR TYPES OF HUMAN TEETH
1. Incisors (8 in adult)
2. Cuspids (Canines)
3. Bicuspids (Premolars) (8 in adult)
4. Molars (12 in adult)
Third molars (wisdom)

14. FOUR TYPES OF HUMAN TEETH

15. WISDOM TEETH

16. THE PROCESS
Initial chemical digestion depends on an
accessory organ – the salivary gland.
Chemical digestion involves enzymatic
action, which is accomplished through
the saliva.

17. SALIVARY GLANDS
1. Parotid gland – lies in front of ear; empties saliva
near the second upper molar
2. Sublingual gland – lies under the floor of the
mouth; empties saliva by numerous sublingual
ducts
3. Submandibular gland – lies deep in the mouth;
empties saliva on either side of the lingual
frenulum (small fold under the tongue)

18. SALIVARY GLANDS

19. B. PHARYNX AND ESOPHAGUS
The bolus is the end product
of the food that has been
chewed, partially digested,
and lubricated by the saliva.

20. QUESTION
HOW COME THE FOOD
ENTER THE ESOPHAGUS
AND DOES NOT GO THE
OTHER WAY? (RESPIRATORY
TRACT)

21. B. PHARYNX AND ESOPHAGUS
A flap called epiglottis
closes the air openings
when food is
swallowed. It prevents
the bolus from
entering the trachea
and ensures food
enters the esophagus.

23. C. THE STOMACH
The bolus passes through the stomach after
leaving the esophagus. The stomach is a
highly muscularized J-shaped sac that stores
food and continues the digestion.

25. C. THE STOMACH
The environment is highly acidic.
1. Chief cells – release pepsinogen (form
pepsin once in contact with acid)
2. Goblet cells – produces mucus that lines
up the cells

26. C. THE STOMACH
Bolus
Chyme

27. C. THE STOMACH
Sphincters – prevent the stomach from
leaking out gastric juices
Cardiac sphincter – near esophagus
Pyloric sphincter – near s. intestine

28. D. THE SMALL INTESTINE
The longest part of
digestive tract.
1. Duodenum
2. Jejunum
3. Ileum

29. D. THE SMALL INTESTINE
The completion of chemical digestion
depends on three accessory organs –
pancreas, liver and gallbladder.END OF FOOD
DIGESTION!

30. C. THE SMALL INTESTINE
Enzyme Digestive organ Function
Salivary amylase Mouth
Breaks down starches
into simpler sugars
Pepsin Stomach Breaks down proteins
Maltase, lactase,
sucrose
Small intestine
Breaks down sugars
into simpler molecules
Peptidase
Breaks down proteins
into amino acids
Trypsin and
chymotrypsin
Small intestine,
pancreas
Continue proteins
breakdown
Amylase
Continue starches
breakdown
Lipase Breaks down fats

31. D. THE SMALL INTESTINE
Bolus
Chyme
Chyle
SEGMENTATION

32. D. THE SMALL INTESTINE
The final products are – amino acids,
monosaccharides, fatty acids and glycerol

33. E. THE LARGE INTESTINE
The site where undigested materials are
transported and water absorption happens.

36. F. RECTUM
The site of feces formation and temporary
storage of undigested food.

37. G. ANUS
The site where feces are expelled out of the
body.

39. SOME COMMON DIGESTIVE DISORDERS
1. Dental caries – tooth decay or cavity.
Characterized by demineralization and
destruction of the different tooth layers
(enamel, dentin, cementum).

41. SOME COMMON DIGESTIVE DISORDERS
2. Heartburn – characterized by burning
sensation in chest. It is caused by the reflux of
acid from the stomach back to esophagus.

43. SOME COMMON DIGESTIVE DISORDERS
3. Gastric ulcer (stomach ulcer) – caused by H.
pylori. The caustic effects of acid and pepsin
reach the walls of the stomach and cause
lesions.

45. SOME COMMON DIGESTIVE DISORDERS
4. Appendicitis – inflammation of appendicitis.
The result of obstruction of the inside space of
appendix. The appendix then accumulates
mucus and swells.

47. SOME COMMON DIGESTIVE DISORDERS
5. Diarrhea –
characterized by having
three or more loose liquid
bowel movements per
day.