This PowerPoint presentation details out the anatomy of the human digestive system. Their are general terminologies that involves the topic but over-all this work focuses on how digestion takes place in the human body. The details coming from this presentation are combined from four different and liable sources/references including Biology (Thomson Asian Edition). I can say that this presentation is brief and well-organized so I hope this could help you in your class or seminars. Thanks.

1. THE DIGESTIVE SYSTEM
ANATOMY OF THE HUMAN DIGESTIVE SYSTEM

2. GENERAL TERMINOLOGIES
NUTRITION – the process of taking in and
using food
NUTRIENTS – substances in food that are
used as energy sources to run the
system of the body
DIGESTIVE SYSTEM – the organs and glands
in the body that are responsible
for digestion
DIGESTION – the breakdown of food to
smaller molecules

3. TWO TYPES OF DIGESTIVE SYSTEM
INCOMPLETE DIGESTIVE SYSTEM – common
among invertebrates, there is only a
single opening for the ingestion of food
(an anus is absent)
COMPLETE DIGESTIVE SYSTEM – common
among nematodes, annelids, mollusks,
echinoderms, and vertebrates, this type
has digestive tubes with two openings
(a mouth and an anus)

4. THE HUMAN
DIGESTIVE SYSTEM

5. THE HUMAN DIGESTIVE TRACT
The human digestive tract is a
long, coiled, muscular tube that
stretches from the mouth to the
anus.
From mouth to the anus, the
human food tube or the digestive
tract is about nine meters long.

6. THE HUMAN DIGESTIVE TRACT MEASUREMENT
9meters

7. SPECIALIZED REGIONS WHERE DIGESTION TAKES PLACE
1. Food processing begins in the mouth.
2. The bite food is then swallowed and is moved through
the pharynx into the esophagus.
3. Then, food is mechanically and enzymatically digested
in the stomach.
4. Most enzymatic digestion takes place in the
small intestine.
5. The large intestine then eliminates wastes leading to
the opening for the elimination of wastes called anus.

8. SPECIALIZED REGIONS WHERE DIGESTION TAKES PLACE
MOUTH
PHARYNX
ESOPHAGUS
STOMACH
SMALL INTESTINE
LARGE INTESTINE
ANUS

9. DIGESTIVE SYSTEM WITH OTHER ASSISTING ORGANS

10. WHERE DIGESTION TAKES PLACE WITH ASSISTING ORGANS
1. Food processing begins in the mouth.
2. The bite food is then swallowed and is moved through
the pharynx into the esophagus.
3. Then, food is mechanically and enzymatically digested
in the stomach.
4. The liver secretes bile.
5. The pancreas secretes digestive enzymes.

11. WHERE DIGESTION TAKES PLACE WITH ASSISTING ORGANS
6. Most enzymatic digestion takes place in the
small intestine.
7. Nutrients are then digested as they move the
digestive tract.
8. Nerves and hormones regulate digestion.
9. Absorption takes place mainly through the villi of the
small intestine.
10. The large intestine then eliminates wastes leading to
the opening for the elimination of wastes called anus.

12. TWO PHASES OF DIGESTION
MECHANICAL PHASE – involves the
breaking up of food into small pieces,
pushing the food down the food tube,
and mixing with it digestive juices
CHEMICAL PHASE – involves the further
breaking up of the larger molecules of
food into smaller molecules by the action
of digestive enzymes

13. HOW DIGESTION
IS DONE?

14. MECHANICAL PHASE OF DIGESTION IN THE MOUTH
MECHANICAL DIGESTION starts in the
mouth (Mastication) where four kinds of
teeth tear the food into pieces:
Four kinds of teeth:
1. INCISORS – thin-edged for cutting
food
2. CANINES – are pointed used for tearing
3. MOLARS & PREMOLARS – specialized for
crushing and grinding

15. THE HUMAN TEETH / MAN’S DENTAL SET

16. THE TEMPORARY DENTAL SET OF MAN
TEETH UPPER JAW LOWER JAW TOTAL
Incisors 2 ; 2 2 ; 2 8
Canine 1 ; 1 1 ; 1 4
Premolars 0 0 0
Molars 2 ; 2 2 ; 2 8
TOTAL: 20

17. THE PERMANENT DENTAL SET OF MAN
TEETH UPPER JAW LOWER JAW TOTAL
Incisors 2 ; 2 2 ; 2 8
Canine 1 ; 1 1 ; 1 4
Premolars 2 ; 2 2 ; 2 8
Molars 3 ; 3 3 ; 3 12
TOTAL: 32

18. CHEMICAL DIGESTION IN THE MOUTH
Our mouth has salivary glands that
secrete saliva. This saliva contains
the enzyme called salivary amylase.
This salivary amylase and the
enzyme called maltase (catalyzes
maltose into glucose) enables the
chemical digestion of the mouth to
occur.

19. THE HUMAN SALIVARY GLANDS
These salivary glands secrete salivary amylase.

20. HOW MOUTH’S CHEMICAL DIGESTION IS DONE?
CARBOHYDRATES
SALIVARY AMYLASE
or PTYALIN
I. STARCH Maltose
(or amylum/amylose) (a double sugar)
MALTASE
II. MALTOSE Glucose
(a simple sugar)

21. THE TONGUE, PHARYNX, & ESOPHAGUS
The tongue also helps in the mechanical
digestion of food. It helps push and mix
food while the back part of it secretes
mucus making swallowing easier.
The pharynx and esophagus conduct
food to the stomach. After being chewed,
the food is swallowed through the
pharynx extending to the esophagus.

22. MECHANICAL PHASE: THE PROCESS OF PERISTALSIS

23. PHARYNX AND ESOPHAGUS ON CONDUCTING FOOD
PHARYNX or THROAT – the hallway of food
used for both digestive and respiratory system.
ESOPHAGUS – canal that connects throat to
the stomach
EPIGLOTTIS – tissue that closes the opening
to the airway during swallowing
PERISTALSIS – pushes soft mass of chewed
food (bolus) and mixes it with digestive juices in
stomach and small intestine
ANTI-PERISTALSIS – results vomiting which
prevents body from harmful substances that
are ingested.

24. FOOD’S DIGESTION IN THE STOMACH
Stomach’s entrance is closed by a ring
muscle at the end of the esophagus.
When empty, the stomach is collapsed
and shaped almost like a hot dog.
Once food enters, the folds of stomach
wall called rugae smooths out and
expands to more than a liter.

25. THE STRUCTURE OF THE STOMACH

26. ENZYMATIC DIGESTION IN THE STOMACH
The stomach secretes millions of
gastric glands.
1. THE PARIETAL CELLS in the gastric glands
secrete hydrochloric acid and intrinsic
factor, a substance needed for adequate
absorption of vitamin B12.
2. THE CHIEF CELLS secrete pepsinogen (an
inactive enzyme precursor). When
pepsinogen comes in contact with the
acidic gastric juice, it becomes pepsin (the
main digestive enzyme of the stomach).

27. FOOD’S DIGESTION IN THE SMALL INTESTINE
Digestion is completed in the small
intestine and nutrients are absorbed
through its wall.
The small intestine is about 5 to 6
meters (about 17ft.) in length and has
three regions.
1. Duodenum
2. Jejunum
3. Ileum

28. THE THREE REGIONS OF THE SMALL INTESTINE
Most chemical digestion takes place in the
duodenum, the first layer of the small intestine.

29. THE LAYERS OF THE SMALL INTESTINE (Labelled)

30. THE LIVER SECRETES BILE
LIVER – the largest internal organ of the
body and also one of the most
complex organs which lies in the
upper right abdomen just under
the diaphragm.
-- the liver secretes BILE
BILE – the fluid secreted by the liver
which emulsifies fats

31. THE LIVER SECRETING BILE

32. FUNCTIONS OF A LIVER
Secretes bile.
Helps maintain homeostasis by removing
or adding nutrients to the blood.
Converts excess glucose to glycogen and
stores it.
Converts excess amino acids to fatty
acids and urea
Stores iron and certain vitamins.
Detoxifies alcohol and other drugs and
poisons.

33. THE PANCREAS SECRETES DIGESTIVE ENZYMES
PANCREAS – an elongated gland that
secretes both digestive
enzymes and hormones
that help regulate the level
of glucose in the blood
– the enzymes secreted by
the pancreas are called
trypsin and chymotrypsin.

34. Trypsin and Chymotrypsin digest
polypeptides to dipeptides resulting to:
PANCREATIC
LIPASE
Degrades fats
PANCREATIC
AMYLASE
Breaks down almost all types of
carbohydrates except cellulose
disaccharides
RIBONUCLEASE
and
DEOXYRIBONUCLEASE
Split RNA and DNA to free
nucleotides

35. THE PANCREAS RELEASING DIGESTIVE ENZYMES

36. SO HOW DOES CHEMICAL DIGESTION IN THE
SMALL INTESTINE REALLY DONE?
1. Bile from the liver and digestive enzymes from the
pancreas released into the duodenum.
2. These two then acted on the chyme (a semi fluid
mass of digested food expelled by the stomach into the
duodenum.
3. Then enzymes produced by the epithelial cells lining
the duodenum catalyze the final steps in the digestion of
the major types of nutrients.

37. THE DIGESTED NUTRIENTS
Chyme moves through the digestive
tract by peristalsis, mixing contractions,
and motions of the villi. Nutrients in the
chyme come into contact with enzymes
that digest them.
1. Carbohydrates are digested to
monosaccharides or simple sugars
2. Proteins are digested to amino
acids
3. Fats are digested to fatty acids
and monoacylglycerols

38. CHEMICAL DIGESTION OF COMPLEX MOLECULES
proteases
PROTEINS Maltose
lipase
FATS fatty acids,
glycerol
carbohydrases
CARBOHYDRATES Simple sugars

39. NERVES AND HORMONES REGULATE DIGESTION
Secretion of other digestive juices is
regulated by nerves and hormones.
This called enteric nervous system
continues to regulate many motor and and
sectory activities of the digestive system
even if sympathetic and parasympathetic
nerves to these organs are cut.
Several hormones including gastrin,
secretin, cholecystokinin (CCK), and gastric
inhibitory peptide (GIP), help regulate the
digestive system.

40. SOME HORMONES THAT REGULATE DIGESTION
HORMONE SOURCE TARGET
TISSUE
ACTIONS
Gastrin Stomach
(mucosa)
Stomach
(gastric glands)
Stimulates gastric glands
to secrete pepsinogen
Secretin Duodenum
(mucosa)
Pancreas L
Liver
Signals secretion of
sodium bicarbonate
Stimulates bile secretion
Cholecystokinin
(CCK)
Duodenum
(mucosa)
Pancreas
Gallbladder
Stimulates release of
digestive enzymes
Stimulates emptying of
bile
Gastric
Inhibitoy
Peptide (GIP)
Duodenum
(mucosa)
Stomach Decreases stomach
churning, thus slowing
emptying

41. ABSORPTION IN ACTION
ABSORPTION is the process by
which substances are taken in by cells
of the food tube.
Absorption takes place mainly
through the villi of the small
intestine.
Digested food in the form of amino
acids, simple sugars, fatty acids, and
glycerol diffuse into the cells of the
villi.

42. THE STRUCTURE OF THE VILLUS (Plural VILLI)

43. THE PROCESS OF ABSORPTION
1. Most of the digested food diffuse into capillaries
and reach the blood, while fatty acids and glycerol
diffuse into the lacteals and reach another
circulating fluid called lymph.
2. Through diffusion, digested food reaches the
blood and lymph and undergoes a process called
circulation.
3. The circulating fluids distribute the digested food
to all the cells of the body.

44. THE LARGE INTESTINE ELIMINATES WASTE
Undigested food passes through
the large intestine.
Although shorter in length than
the small intestine, it is called
“large” because its diameter is
greater than that of the small
intestine.
The large intestine is 1.3m (about
4ft.) in length.

45. THE STRUCTURE OF THE LARGE INTESTINE

46. DESTINCTION BETWEEN ELIMINATION & EXCRETION
ELIMINATION – the process of getting
rid of digestive wastes – materials that
have not been absorbed from the
digestive tract and did not participate in
metabolic activities.
EXCRETION – the process of getting rid
of metabolic wastes, which in mammals
is mainly the function of the kidneys and
lungs.
NOTE: However, the large intestine
excrete bile pigments.

47. SOME ILLNESS INVOLVING ELIMINATION OF WASTES
DIARRHEA – This happens when
chyme passes too rapidly (defecation).
This may be caused by anxiety, certain
foods, or disease organisms that irritate
the intestinal lining.
CONSTIPATION – This is the result of
the too slowly passing of chyme through
the intestine.
COLORECTAL CANCER– This is
commonly known as the cancer of the
colon and rectum.

48. IMPORTANCE OF
FOOD-GETTING
AND DIGESTION

49. FUNCTIONS OF FOOD IN THE BODY
Food in this topic will include not
only the organic nutrients but also
water, minerals, and vitamins.
Be reminded that three building
materials of body tissues consists
largely of 67% water, 15% proteins, and
13% fats.
Mineral solids like calcium,
phosphorus, iron, etc. Are also used as
building materials of the body.

50. THE WHYs TO TAKE FOOD
Carbohydrates provide energy
Lipids provide energy and are used to
make biological molecules
Proteins serves as enzymes and as
structural components of cells.
Vitamins are organic compounds
essential for normal metabolism.
Minerals are inorganic nutrients.
Antioxidants protect against oxidants
Phytochemicals play important roles in
maintaining health.

51. CARBOHYDRATES PROVIDING BODY ENERGY

52. LIPIDS OR FATS FOR OUR BODY

53. PROTEINS – WE NEED IT, WE DON’T!

54. SOME VITAMINS THAT OUR BODY NEEDS

55. MINERALS THAT OUR BODY NEEDS

56. ANTIOXIDANTS IN ACTION

57. PHYTOCHEMICALS FOR MAINTAINING HEALTH

58. ENERGY SPENT IN SOME DAILY CHORES
ACTIVITY AMOUNT OF ENERGY USED
In calories per kilogram of body weight
per hour
DRESSING UP 0.7
EATING 0.4
WALKING MODERATELY 2.0
WALKING FAST 3.5
RUNNING 7.0
SWIMMING 7.9
WRITING 0.4
WASHING DISHES 1.0
WASHING LAUNDRY 1.5
SWEEPING THE FLOOR 1.4

59. UNDERNUTRITION IS A SERIOUS PROBLEM
Millions of people do not have enough
to eat, or do not eat a balance diet.
Malnourished individuals are weak,
easily fatigued, and highly susceptible to
infections.
In young children, severe protein
malnutrition results to a condition called
kwashiorkor (first-second). This is the
situation in which a first child is displaced
from its mother’s breast because a
younger sibling is born.

60. MALNUTRITION: KWASHIORKOR AND MARASMUS

61. THE IMPACT OF MALNUTRITION

62. OBESITY IS A SERIOUS PROBLEM
Obesity is the excess of
accumulation of body fats.
The World Health Organization
(WHO) considers obesity among the
top 19 global health problems.
Obesity is a major risk factor for
heart disease, diabetes mellitus,
osteoarthritis, and certain types of
cancer, including breast and colon
cancers.

63. OBESITY

64. THE IMPACT OF OBESITY

65. TIPS FOR A HEALTHY BODY
Have a balance diet.
Watch the amount you eat.
Chew your food well and eat
slowly to facilitate digestion.
Drink plenty of water.
Balance your food with
activities such as exercise.

66. YOUR BALANCE DIET SHOULD INCLUDE:
Vegetables and fruits
Milk and milk products
Meat including fish
Cereals such as rice
Other healthy foods
Always Remember:
The greatest wealth
is your HEALTH!

67. Topic References:
Biology (Thomson Asian Edition)
by Solomon, Berg, Martin
Integrated Science II (Biology) by
L. M. Rabago, et.al
Functional Biology (Modular
Approach) by Lilia M. Rabago
Science and Technology for the
future II by Lourdes F. Lozano, et. al

68. THE END :)
Prepared by: Mr. Ranulfo T. Bacus