2. 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
GENERAL TERMINOLOGIES
4. 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.
THE HUMAN DIGESTIVE TRACT
6. 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.
7. SPECIALIZED REGIONS WHERE DIGESTION TAKES PLACE
MOUTH
PHARYNX
ESOPHAGUS
STOMACH
SMALL INTESTINE
LARGE INTESTINE
ANUS
9. 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.
10. 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. 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
MECHANICAL PHASE OF DIGESTION IN THE MOUTH
14. 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
THE TEMPORARY DENTAL SET OF MAN
15. 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
THE PERMANENT DENTAL SET OF MAN
16. 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.
CHEMICAL DIGESTION IN THE MOUTH
17. THE HUMAN SALIVARY GLANDS
These salivary glands secrete salivary amylase.
18. CARBOHYDRATES
I. STARCH Maltose
II. MALTOSE Glucose
SALIVARY AMYLASE
or PTYALIN
(or amylum/amylose) (a double sugar)
MALTASE
(a simple sugar)
HOW MOUTH’S CHEMICAL DIGESTION IS DONE?
19. 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.
THE TONGUE, PHARYNX, & ESOPHAGUS
21. 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.
FOOD’S DIGESTION IN THE STOMACH
23. 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).
ENZYMATIC DIGESTION IN THE STOMACH
24. 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.
ABSORPTION IN ACTION
26. 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.
27. 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
FOOD’S DIGESTION IN THE SMALL INTESTINE
28. THE THREE REGIONS OF THE SMALL INTESTINE
Most chemical digestion takes place in the
duodenum, the first layer of the small intestine.
30. The is a short structure (about 20–25 cm long)
continuous with the stomach and shaped like a It
surrounds the head of the pancreas. It receives
gastric chyme from the stomach, together with
digestive juices from the pancreas (digestive enzymes)
and the gall bladder (bile). The digestive enzymes
break down proteins and bile and emulsify fats
into micelles.
duodenum
31. is the midsection of the small intestine,
connecting the duodenum to the ileum. It is
about 2.5 m long, and contains the plicae
circulares, and villi that increase its surface area.
Products of digestion (sugars, amino acids, and
fatty acids) are absorbed into the bloodstream
here. The suspensory muscle of
duodenum marks the division between the
duodenum and the jejunum.
jejunum
32. The final section of the small
intestine. It is about 3 m long, and
contains villi similar to the jejunum. It
absorbs mainly vitamin B12 and bile
acids, as well as any other remaining
nutrients. The ileum joins to
the cecum of the large intestine at
the ileocecal junction.
ileum
33. 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
THE LIVER SECRETES BILE
35. 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.
THE PANCREAS SECRETES DIGESTIVE ENZYMES
37. PROTEINS Maltose
FATS fatty acids,
glycerol
CARBOHYDRATES Simple sugars
proteases
CHEMICAL DIGESTION OF COMPLEX MOLECULES
lipase
carbohydrases
38. 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.
THE LARGE INTESTINE ELIMINATES WASTE
40. The Cecum is the first section of the colon and
involved in the digestion is a structure of the colon,
not involved in digestion and considered to be part of
the gut-associated lymphoid tissue; the function of
the appendix is unknown.
Cecum
41. The ascending colon runs through the abdominal
cavity, upwards toward the transverse colon for
approximately eight inches (20 cm) One of the main
functions of the colon is to remove the water and
other key nutrients from waste material and recycle it
back into the body
Ascending colon
42. part of the colon from the hepatic flexure to the
splenic flexure (the turn of the colon by the spleen).
The transverse colon hangs off the stomach,.
Transverse colon
43. The function of the descending colon in the
digestive system is to store faeces that will be
emptied into the rectum. It is retroperitoneal in two -
thirds of humans. In the other third, it has a (usually
short) mesentery. The arterial supply comes via
theleft colic artery.
Descending colon
44. The name sigmoid means S-shaped The
walls of the sigmoid colon are muscular, and
contract to increasethe pressure inside the
colon, causing the stool to move into the
rectum
Rectum
Rectum is the last section of the colon
Sigmoid colon
46. 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.
FUNCTIONS OF FOOD IN THE BODY
47. 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.
TIPS FOR A HEALTHY BODY
48. 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!
YOUR BALANCE DIET SHOULD INCLUDE:
