Biology Natural Science 1--Digestive System Stomach Myth Intestines body internal organs

1. DIGESTIVE SYSTEM
NATSCI [MWF] 1 :30-2:30 PM

3. INTRODUCTION
 The digestive
system is used for
breaking down food
into nutrients which
then pass into the
circulatory system
and are taken to
where they are
needed in the body.

4. FUNCTION OF DIGESTIVE SYSTEM
Prepares food for use by cells
through “Five Basic Activities:”
1) INGESTION or the taking of food
into the body
2) PERISTALSIS or the physical
movement or pushing of food
along the digestive tract

5. 3) DIGESTION or the breakdown of food
by both mechanical and chemical
mechanisms
GOAL: Break down into :
– Monosaccarides, amino acids, fatty acids
– Absorbed through the epithelium

6. 4) ABSORPTION or the passage of
digested food from the digestive
track into the cardiovascular and
lymphatic systems for distribution of
the body’s cells
5) DEFECATION or the elimination
from the body of those substances
that are indigestible and cannot be
absorbed

7. Digestive System:
“Gastrointestinal System”

8. The organs of digestion are
part of two main groups.
• 1ST: DIGESTIVE TRACT
• 2ND: ACCESSORY ORGANS
OF THE TRACT

9. Description:
THE DIGESTIVE TRACT
 (gastrointestinal (GI) tract)
• Food passes through:
–starts at the mouth,
–continues to the esophagus,
– stomach,
–small intestine,
–large intestine (the colon / rectum)
–And ends at the anus.

10. Description:
THE DIGESTIVE TRACT
>>The entire system — from mouth to
anus — is about 30 feet (9 meters)
long.

11. Description:
ACCESSORY ORGANS
• Food does NOT pass through:
–Teeth
–Tongue
–Salivary glands
–Liver
–Gallbladder
–Pancreas

12. THE DIGESTIVE TRACT
Mouth or oral cavity
• “Buccal cavity”
• The mouth is the beginning of the
digestive tract;
• digestion starts here when taking
the first bite of food.

13. Mouth or oral cavity

14. Mouth or oral cavity
The food is chemically broken
down by amylase-an enzyme in
saliva that breaks down
carbohydrates.

15. ACCESSORY ORGAN
 Tongue
• Consists of skeletal muscle covered
with mucous membrane
• Divided into symmetrical halves by
septum called lingual frenulum

16. Tongue

17. Tongue
• Papillae – covers the upper
surface and sides of the tongue
*Filiform papillae - found at the
front of the tongue (rough and
important in licking)
–threadlike elevations covering
most of the tongue surface.

20. Papillae
-Fungiform papillae (contain taste buds)
–knoblike projections of the tongue scattered
among the filiform papillae.
-Circumvallate papillae (contain taste
buds)
–eight to twelve large papillae arranged in a
V near the base of the tongue.

21. ACCESSORY ORGAN
 Salivary glands
• the one that secretes saliva in the
mouth,
• Saliva is a watery substance located
in the mouths of organisms contains
an enzyme - salivary amylase,
–which breaks down starch.

22. ACCESSORY ORGAN
Three pairs of salivary glands:
• Parotid gland—(secretory cell: serous)
• The submandibular or submaxillary
gland—(secretory cell:mixed)
• The sublingual gland—
– (secretory cell:mucous)

23. Salivary glands

25. Teeth
-known as
dentes
-are part of the
skeletal system
-play a key
role in digestion
ACCESSORY ORGANS

26. ACCESSORY ORGANS
Teeth
-In carnivores,
*are designed for killing and
breaking down meat.
-In Herbivores,
*for grinding plants and other
food to ease them through the
digestion process

27. ACCESSORY ORGANS
₪ Tooth is composed of:
-the crown--(covered with enamel)
-the neck or cervix
-the root

28. Tooth

30. ACCESSORY ORGANS
“The Four types of teeth”

31. Four types of teeth

32.  (1) The Incisors
• The 8 front teeth
• are used to cut
food
 (2) The Canine (4
eyeteeth)
• Used to tear food
• are used to cut
food
• Having only 1 cusp
or cuspids

33. (3) The Molars (back
teeth) are used for
chewing and grinding
food.
(4) The 8 Premolars
(bicuspids) have a flat
biting surface, they
tear and crush food .

34. THE PHARYNX
 FUNCTION:
• Is to begin the
process of
swallowing or
deglutition
 Is a common
passageway for
food and air.
 Is divided into:
– the NASOPHARYNX
– The OROPHARYNX
and
– The
LARYNGOPHARYNX

36. Division of Pharynx
 Nasopharynx
• Region posterior
to the nasal
cavity, from the
internal nares
(choanae) to soft
palate

37. Division of Pharynx
Oropharynx
• Region
posterior to the
root of the
tongue

38. Division of Pharynx
Laryngopharynx
• Region posterior
to, behind larynx,
from the epiglottis
to cricoid cartilage
(larynx)

39. THE ESOPHAGUS
 Is to secrete mucus
and transport food
to the stomach
through an opening
in the diaphragm
called the
esophageal hiatus
THE DIGESTIVE TRACT

40. THE ESOPHAGUS
 it uses
PERISTALSIS –
involuntary waves of
muscle contraction
to help push food
down to the
stomach through the
lower esophageal
sphincter
THE DIGESTIVE TRACT

41. lower esophageal sphincter
--Functions as to
keep food and
stomach acid from
coming back up in
to the esophagus

42. THE STOMACH
 Begins the chemical
breakdown of
proteins through the
enzyme pepsin
 Breaks up food
mechanically by
churning its contents
THE DIGESTIVE TRACT

43. THE STOMACH
 It has folds called rugae
and is a big muscular
pouch which churns the
bolus and mixes it with
gastric juice- a mixture
of stomach acid, mucus
and enzymes.

44. 4 parts of stomach

45. Cardia
• Surrounds the gastroesophageal
sphincter
4 parts of stomach

46. Fundus
• The rounded
portion above
and to the left
of the cardia
4 parts of stomach

47. The body
• The large
central portion
of the stomach
below the
fundus
4 parts of stomach

48. Pylorus or
antrum
• The narrow inferior
region that
connects with the
duodenum of the
small intestine via
the pyloric
sphincter
4 parts of stomach

49.  Dual function:
(a) Its acini
produce digestive
enzymes that get
carried by the
pancreatic duct to
the duodenum of
the small intestine
THE DIGESTIVE TRACT
THE PANCREAS

50. (b) Its pancreatic
islets secrete the
hormones insulin
and glucagon into
the blood to control
blood sugar levels
THE DIGESTIVE TRACT
THE PANCREAS

51.  Divided into :
• The head- is the widest part of the
organ
• The body - the tapered left side that
extends slightly upward
• The tail -
THE PANCREAS

52.  The pancreas is made up of two types of
glands:
• Exocrine
secretes:digestive enzymes. These enzymes are
secreted into a network of ducts that join the main
pancreatic duct, which runs the length of the
pancreas.
• Endocrine
consists of the islets of Langerhans, secretes
hormones into the bloodstream.
THE PANCREAS

53. • Largest organ
of the body
• Produces bile
• Break up fats
• Functional units
–lobules
THE LIVER
ACCESSORY ORGAN

54.  It stores copper, iron and vitamins
A,D,E, and K.
 It stores or transforms poison into less
harmful substances
THE LIVER

55. Division of the liver
(a) right lobe
(b) left lobe

56.  It stores and
concentrates bile
produced by the
liver lobules
ACCESSORY ORGAN
THE GALLBLADDER

57.  Where the major
portion of absorption
and digestion occurs
 Approximately:
• Length: 21 feet
• Diameter:1 inch
 Divided into 3
portions
THE DIGESTIVE TRACT
THE SMALL INTESTINE

58. The three portions :
 1st: duodenum
• The shortest part
• Length: 10 inches
long
 2nd: jejunum
• Length: 10 inches
long
• Extends to the 3rd
part
 3rd: ileum
• Length: 12 feet long
• Joins the large
intestine

59. THE DIGESTIVE TRACT
 Length: 5 feet
 Diameter: averages
2.5 inches
 FUNCTIONS:
• Absorption of water
• Manufacturing and
absorption of certain
vitamin
• Formation and
expulsion of the
FECES
THE LARGE INTESTINE

60.  Attached to the
posterior wall of the
abdomen by
extensions of its
visceral peritoneum
known as
mesocolon
THE DIGESTIVE TRACT
THE LARGE INTESTINE

61. Four principal regions
 (1) the cecum
• The pouchlike first part of the large
intestine
• Attached to the close end of the cecum
is the twisted tube known as the
vermiform appendix (length 3 inches)
THE LARGE INTESTINE

62.  (2) the colon
• The largest part.
• Looks like a tube of consecutive pouches
• The pouches are called haustrae
• Parts:
– Ascending Colon
– Tranverse colon
– Descending colon
– Sigmoid colon

63.  (3) the rectum
• The last 7-8 inches of the
gastrointestinal tract
• Eliminate feces
• What’s left over?
– undigested materials:
– mainly cellulose from plants
– called roughage or fiber
– keeps everything moving & cleans out
intestines
• It is situated anterior to the sacrum and

64. • It is situated anterior to the sacrum and
coccyx.
 (4) anal canal
• The terminal 1 inch of the rectum

65. THE DIGESTIVE TRACT
ANUS
 The opening of the
anal canal to the
exterior
 The last part of the
digestive system

66. Human digestive system

67. THE ENZYMES
 Mouth:
secretes Salivary Amylase which down
starches into sigars
 Stomach:
-Secretes Pepsin which breaks down
proteins and hydrochloric acid which
provides an acid environment to
kill bacteria

68.  Pancreas:
• secretes amylase, which continues the
breakdown of starch,
• trypsin which continues the break down of
proteins
• Lipase which breaks down fats
 Small Intestine:
Secretes peptidase and maltase which
converts the remaining sugars into glucose

69. Liver:
• Secretes Bile which breaks down fats and
stores it in the gallbladder

70. HISTOLOGY
The walls of the alimentary canal
from the esophagus to the anal
canal have the same arrangement
of tissue layers.
• These layers are referred to as
“coats” or “tunics”

71. HISTOLOGY
The Four Coats or TUNICS of the tract
(From the inside out)
1)The MUCOSA
2)SUBMUCOSA
3)MUSCULARIS
4)ADVENTITIA or SEROSA

72. Tunics

75. 1) Tunica mucosa:
• This layer is composed of
epithelium, connective tissue and
muscle. These tissues can
usually be found in distinct layers
as follows:

76. Tunica mucosa

77. THREE LAYERS
1) lamina epithelialis mucosae:
–consists only of epithelium
2) lamina propria mucosae:
–consists of either loose areolar or
reticular connective tissue
3) lamina muscularis mucosae:
–consists of smooth muscle
–which permits the mucosa to
dynamically move and fold.

78. THREE LAYERS:

79. Tunics

80. The magnification of all four images is identical
and the epithelial layer is oriented toward the top.

81. 2) Tunica Submucosa?
• Consists of loose connective
tissue that binds the tunica
mucosa to the next layer, the
tunica muscularis,nerves, blood
vessels, and glands in some
organs

84. 3) Tunica muscularis:
• consists of at leasttwo layers, an
inner circular and an outer
longitudinal with parasympathetic
ganglia located between the
layers

86. Tunics

87. 4) Tunica Adventitia or
Tunica Serosa:
• consists of loose connective
tissue.
* If the organ is surrounded by other tissues,
this layer is called a tunica adventitia and its
connective tissueblends with that of the
surrounding tissues.
* If the organ is suspended in the body cavity,
this layer is called a tunica serosa and it is
covered by a simple squamous epithelium that
is called mesothelium.

88. DIGESTIVE SYSTEM DISORDERS
 Ulcerative Colitis
-An inflammatory
disease
-affects only the
large intestine.
Diarrhea occurs when
waste products move
through the large
intestine too quickly;
constipation results
when this movement
is too slow.

89.  GERD
(Gastroesophageal reflux
disease)
-occurs when the
lower esophageal
sphincter relaxes at
the wrong times,
allowing acid from
the stomach to enter
the esophagus.

90. GERD
-possible cause:
a hiatal hernia,
a protrusion of
this same
sphincter and
the upper
portion of the
stomach into
the chest cavity

91. What is a fart exactly?

92.  Why Do Farts Smell Bad?
• The more sulfur-rich your diet is, the more
terrible your farts will smell. Some foods
contain more sulfur than others, which is
why eating things like beans, cabbage,
cheese, soda, and eggs can cause gas
that will peel the paint off the walls!

93. 1) Farts Are Flammable

94. 2) If You Hold Them In, They'll Just
Come Out When You Sleep
3) People Even Fart After Death

95. TOP 10 FOOD MYTHS
 Myth #1:
Drinking water in between your meals will mess
will mess up your digestion
 Myth #2:
Having fruits immediately after a meal is not good
is not good for you
 Myth #3:
Papaya should be avoided during pregnancies

96.  Myth #4:
The skin of an apple contains no nutrients
nutrients
 Myth #5:
Eating after 7 pm will make you fat
 Myth #6:
Having milk immediately after eating fish

97.  Myth #8:
Having chocolate causes acne
 Myth #9:
Having kesar (saffron) during pregnancy makes your
makes your baby fair
 Myth #10:
If you swallow a chewing gum, it stays in your
your stomach for seven years before it gets digested

98. Facts and fallacies
 Ulcers
-Spicy food and stress cause
stomach ulcers. False.
almost all stomach ulcers are caused
either by infection with a bacterium called
Helicobacter pylori (H. pylori) or by use of
pain medications such as aspirin,
ibuprofen, or naproxen, the so-called
nonsteroidal anti-inflammatory drugs
(NSAIDs).

99.  Heartburn
Smoking a cigarette helps relieve
heartburn. False.
Actually, cigarette smoking
contributes to heartburn.