2. Function of the digestive systemFunction of the digestive system
• ingestion: taking food and liquid into
mouth
• Secretion: total about 7 liter into lumen
• Mixing and propulsion: through GI
muscle and peristalsis and motility
• Digestion: Breakdown of ingested food
(mechanical and chemical)
• Absorption: Passage of nutrients into the
blood
• Metabolism: Production of cellular
energy (ATP)
• Defecation: waste substance leave the
GI tract through anus
3. Organs of the Digestive SystemOrgans of the Digestive System
• Two main groups
• Alimentary canal or gastrointestinal tract –
continuous coiled hollow tube from mouth to
anus(5-7 meter)
• Accessory digestive organs: teeth ,tongue
,salivary gland ,liver ,gallbladder ,and
pancreas
4. Organs of the Digestive SystemOrgans of the Digestive System
5. Organs of the Alimentary CanalOrgans of the Alimentary Canal
• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Anus
6. Mouth (Oral Cavity) AnatomyMouth (Oral Cavity) Anatomy
• Lips (labia) – protect
the anterior opening
• Cheeks – form the
lateral walls
• Hard palate – forms
the anterior roof
• Soft palate – forms
the posterior roof
• Uvula – fleshy
projection of the
soft palate
7. Mouth (Oral Cavity) AnatomyMouth (Oral Cavity) Anatomy
• Vestibule – space
between lips
externally and teeth
and gums internally
• Oral cavity – area
contained by the
teeth
• Tongue – attached
at hyoid bone and
styloid processes of
the skull, and by the
lingual frenulum
8. TongueTongue
• Dorsum (upper part of
tongue covered with papillae
taste receptor and buds)
• filiform papillae
• fungiform papillae
• circumvallate papillae
• Paltine tonsil and
lingual tonsil
9. Salivary glands
-Parotid gland: In the parotid fossa, three main
structures transverse this gland – facial nerve,
external carotid artery, and retromandibular
vein. The parotid duct opens near the upper 2nd
molar tooth. The gland is completely serous.
- Submandibular gland: Sitting most
posteriorly in the submandibular triangle, it is
supplied by the facial artery and vein.
Submandibular ducts, which cross the lingual
nerves, open on both sides of the tongue
frenulum. It is mostly serous but partially
mucus,.
- Sublingual gland: The smallest salivary
gland sits beneath the oral mucosa in the floor
of the mouth. It has multiple small openings.
This gland is almost completely mucus-
secreting.
10. Teeth
• Teeth
(mechanical breakdown)
– Incisors used for cutting
– Canines used for stabbing
and holding
– Molars large surface area
used for grinding
• Primary or deciduous
teeth 20
• Secondary or permanent
teeth 32
11. Structure of Teeth
Crown - exposed surface of tooth
Neck - boundary between root and crown
Enamel - outer surface (the hardest substance in the
body 95% calcium salts)
Dentin – bone-like, but noncellular(70% calcium
salts)
Pulp cavity - hollow with blood vessels and nerves
Root canal - canal length of root
gingival sulcus - where gum and tooth meet
12. Processes of the MouthProcesses of the Mouth
• Mastication (chewing) of food
• Mixing masticated food with saliva to
produse easy digestied food called
bolus
• Saliva contain 2 enzyme,salivary
amylase and lingual lipase
• Initiation of swallowing by the tongue
• Allowing for the sense of taste
13. Layers of Alimentary Canal OrgansLayers of Alimentary Canal Organs
• Submucosa
•Just beneath the mucosa
•Soft connective tissue with blood vessels,
nerve endings, and lymphatics also contain
submucosal plexus
14. Layers of Alimentary Canal OrgansLayers of Alimentary Canal Organs
• Mucosa
• Innermost layer
• Moist membrane
1. Surface epithelium : secretion and
absorbtion,renew every 5-7 days also
contain enteroendocrine cells
2. Small amount of connective tissue
(lamina propria): contain blood and
lymphatic vessele also contain MALT
3. Small smooth muscle layer
15. Layers of Alimentary Canal OrgansLayers of Alimentary Canal Organs
• Muscularis externa – smooth muscle
1. Inner circular layer
2. Outer longitudinal layer
Between them is myenteric plexus
• Serosa
• Outermost layer – visceral peritoneum
• Layer of serous fluid-producing cells
(mesothelium)
18. Pharynx AnatomyPharynx Anatomy
• Nasopharynx –
not part of the
digestive system
• Oropharynx –
posterior to oral
cavity
• Laryngopharynx –
below the oropharynx
and connected to
the esophagus
19. Pharynx FunctionPharynx Function
• Serves as a passageway for air and
food
• Food is propelled to the esophagus by
two muscle layers
•Longitudinal inner layer
•Circular outer layer
• Food movement is by alternating
contractions of the muscle layers
(peristalsis)
20. EsophagusEsophagus
• Runs from pharynx to stomach through
the diaphragm( 25 cm)
• Conducts food by peristalsis
(slow rhythmic squeezing): contraction
of circular layer above the food and
contraction of longitudinal below the
food
• Passageway for food only (respiratory
system branches off after the pharynx)
21. Esophagus
- The esophagus is posterior to the larynx
and trachea in the neck region and upper
thorax. It travels on the right side of the
descending aorta, passes through the
diaphragm, and connects with the
stomach.
-There are also inner circular and outer
longitudinal muscle layers.
- The upper third is skeletal muscle
(voluntary), middle third is mixed, and lower
third is smooth muscle (involuntary).
-esophagogastric junction is located
approximately at the level of the diaphragm.
Contractions of the diaphragm create sphincter-
like effects, preventing reflux of stomach acids
and content. The esophagogastric junction is a
functional, not anatomical, sphincter.
22. Peristalsis in Esophagus
Bolus of
food
Muscles relax,
allowing
passageway
to open
Stomach
Muscles
contract,
constricting
passageway
and pushing
bolus down
Muscles
relax
Muscles contract
Muscles relax
Muscles contract
23. Stomach AnatomyStomach Anatomy
• Located on the left side of the
abdominal cavity
• Food enters at the
cardioesophageal sphincter
Site where food is churned into chyme
Protein digestion begins
24. Stomach AnatomyStomach Anatomy
• Regions of the stomach
•Cardiac region – near the heart
•Fundus
•Body
•Phylorus – funnel-shaped terminal end
• Food empties into the small intestine at
the pyloric sphincter
28. Stomach AnatomyStomach Anatomy
• Layers of peritoneum attached to the
stomach
•Lesser omentum – attaches the liver to the
lesser curvature
•Greater omentum – attaches the greater
curvature to the transverse colon which
Contains fat to insulate, cushion, and
protect abdominal organs
31. Stomach FunctionsStomach Functions
• Acts as a storage tank for food
• Site of food breakdown and mixing
• Chemical breakdown of protein begins
• Delivers chyme (processed food) to the
small intestine
32. Specialized Mucosa of theSpecialized Mucosa of the
StomachStomach
• Simple columnar epithelium
• Mucous neck cells – produce a sticky
alkaline mucus
• Gastric glands – secrete gastric juice
• Chief cells – produce protein-digesting
enzymes (pepsinogens)
• Parietal cells – produce hydrochloric acid
and Intrinsic factor(B12 absorption)
• Endocrine cells (G cell) – produce gastrin
which stimulates both parietal and chief cells)
33. Structure of the Stomach MucosaStructure of the Stomach Mucosa
• Gastric pits
formed by
folded mucosa
• Glands and
specialized
cells are in the
gastric gland
region
35. Peritoneum
• Is the largest serous membrane of the body consist of
mesothelium
• Divide into
1. Parietal peritoneum: lines the wall of abdominopelvic
cavity internally
2. Visceral peritoneum: cover some oh the organs in the
cavity
3. The space between them contain fluid and called
peritoneal cavity this cavity may be accumulated by
several liters of fluid state called ascites
36. MembranesMembranes
Mesenteries - double sheets of peritoneum, surrounding and
suspending portions of the digestive
organs
Peritoneal folds
1. falciform ligament:- attach the liver to anterior abdominal
wall and diaphragm
2. Greater omentum - "fatty apron", hangs anteriorly from
stomach, double layer encloses fat
3. Lesser omentum - between stomach and liver
4. Mesentery proper - suspends and wraps the small intestine
5. Mesocolon - suspends and wraps the colon, parts are
i. transverse mesocolon
ii. sigmoid mesocolon
• Ascending and descending ,pancreas, first 2 parts of the
duodenum and kidneys are Retroperitoneal structure
40. Small IntestineSmall Intestine
• The body’s major digestive organ
• Site of nutrient absorption into the blood
• Muscular tube extending form the
pyloric sphincter to the ileocecal valve
• Suspended from the posterior
abdominal wall by the mesentery
41. Subdivisions of the Small IntestineSubdivisions of the Small Intestine
• Duodenum(25cm)
•Attached to the stomach
•Curves around the head of the pancreas
•Fixed retroperitoneal structure
• Jejunum (2.5m)
•Attaches anteriorly to the duodenum
• Ileum (3.5m)
•Extends from jejunum to large intestine
44. Duodenum and Related Organs
Liver
Bile
Gall-
bladder
Bile
Duodenum of
small intestine
Acid chyme
Pancreatic
juice
Intestinal enzymes
Stomach
Pancreas
58. CecumCecum –– pocket at proximal end with
Appendix
ColonColon
Ascending colon - on right, between
cecum and right colic flexure
Transverse colon - horizontal portion
Descending colon - left side, between
left colic flexure and
Sigmoid colon - S bend near terminal
end
Regions of Large IntestineRegions of Large Intestine
RectumRectum –– terminal end is anal canal - ending at the anus -
which has internal involuntary sphincter and external voluntary
sphincter
59. 1. Mucosa - abundant goblet cells, stratified
squamous epithelium near anal canal
2. No villi
3. Longitudinal muscle layer incomplete, forms
three bands or taenia coli
4. Circular muscle - forms pockets or haustra
between bands
Histology of Large IntestineHistology of Large Intestine
68. PancreasPancreas
Slide
• Produces a wide spectrum of digestive
enzymes that break down all categories of food
• Enzymes are secreted into the duodenum
• Alkaline fluid introduced with enzymes
neutralizes acidic chyme
• Endocrine products of pancreas (langerhans
island)
•Insulin
•Glucagons
•Somatostatin
71. Composition and Function of
Pancreatic Juice
• Examples include
• Trypsinogen is activated to trypsin
• Procarboxypeptidase is activated to
carboxypeptidase
• Active enzymes secreted
• Amylase, lipases, and nucleases
• These enzymes require ions or bile for
optimal activity
72. • Retroperitoneal :compose
of head, body and tail
• Endocrine and exocrine
gland
• Common bile duct and
major pancreatic duct lead
to ampulla of vater then to
second part of duodenum
through sphincter of oddi
PancreasPancreas
74. Liver
On right under diaphragm,
largest organ made up of 4
lobes (left and right, caudate,
and quadrate)
Hilus (porta hepatis) –
underside "entry" point
Gall bladder
Microscopic anatomy: Liver lobules and triads
89. NutritionNutrition
Slide
• Nutrient – substance used by the
body for growth, maintenance, and
repair
• Categories of nutrients
•Carbohydrates: simple sugars, starches,
fiber
•Lipids: triglycerides, phospholipids, fatty
acids
•Proteins: amino acids
•Vitamins
•Mineral
•Water
Editor's Notes
Masseter muscle zygomatic arch, cranial ridge = carnivore
Herbivore – diastema plate for incisors to press against
Epiglotis prevents food going down the wrong way
Enamel: Calcium phosphates. Hardest biological material produced.
makes bile, stores excess nutrients, makes plasma proteins, detoxifies harmful materials, stores iron & fat soluble vitamins