The digestive system contains the digestive tract and associated organs. The digestive tract begins at the mouth and includes the esophagus, stomach, small intestine, and large intestine. The major associated organs are the teeth, tongue, salivary glands, liver, gallbladder and pancreas. The digestive system breaks down food into smaller molecules that can be absorbed and used by the body.

1. Digestive System Anatomy
Prepared
By Mr. Chamrane Yter
Medical Student
Of Norton University

2. Digestive system

3. Abdominal Pelvic Regions Anatomy
• There are 9 abdominopelvic region
• Internal organs associate with abdominalpelvic regions

4. Abdominal Pelvic Regions Anatomy

5. Over view of Digestive system

7. Oral cavity
• The mouth contain of three organs:
1 Teeth
2 Tongue
3 Salivary gland
a.Parotid Gland
b.Submandibular Gland
c.Sublingual Gland

8. The Mouth

9. The teeth
• A normal adult mouth has 32 teeth, which (except for wisdom teeth)
have erupted by about age 13:
• Incisors (8 total): The middlemost four teeth on the upper and lower
jaws.
• Canines (4 total): The pointed teeth just outside the incisors.
• Premolars (8 total): Teeth between the canines and molars.
• Molars (8 total): Flat teeth in the rear of the mouth, best at grinding
food.
• Wisdom teeth or third molars (4 total): These teeth erupt at around
age 18, but are often surgically removed to prevent displacement of
other teeth.
The crown of each tooth projects into the mouth. The root of
each tooth descends below the gum line, into the jaw.

10. The Teeth

11. The Tongue

12. Esophagus
• Esophagus is a muscular tube connecting the throat with stomach.
• Length: 25 -33cm
• Diameter: less than 2.5cm
• Two sphincters:
1. The upper esophageal sphincter (UES) is a bundle of muscles at the
top of the esophagus.
2. The lower esophageal sphincter (LES) is a bundle of muscles at the
low end of the esophagus, where it meets the stomach.
Mucous cells on both sides of the inferior sphincter help protect the esophagus from
reflux of stomach acid (GERD : Gastro-Esophageal-Reflux-Disease) that common
called Heartburn.

13. Esophagus
 Structure.
 The esophagus is divided into 3 regions:
 cervical esophagus – begins at the back of the throat and ends at the level of the first rib and
first thoracic vertebra
 thoracic esophagus – begins at the level of the first rib and first thoracic vertebra and ends at the
level of the diaphragm, is further divided into upper, middle and lower regions.
 abdominal esophagus – shortest region of the esophagus that begins at the level of the
diaphragm and ends where the esophagus enters the stomach

15. Peristalsis

16. Stomach
• Stomach is J shape
• The adult stomach varies from 15 to 25 cm long
• Food is converted to a creamy paste called chyme.
The stomach is divided into fours sections:
• 1-Cardia: ជាតំបន់ភ្ជា ប់គ្នា រវាង esophagus and stomach.
• 2-Fundus :ជាតំបន់ផ្នាកកោងខាងក ើននក្កពះ
• 3-Corpus: ជាតំបន់ តួខ្លួនននក្កពះ
• 4-Pylorus: ជាតំបន់តភ្ជា ប់ក្កពះកៅក ះក ៀនតូច

17. Stomach

18. Microscopic Anatomy

19. Microscopic Anatomy

20. Functions of the stomach
• Stomach performs preliminary digestion of proteins by pepsin
– Some digestion of carbohydrates (by salivary amylase)
– Lipids (by lingual lipase)
• Stomach contents
– Become more fluid
– pH approaches 2.0
– Pepsin activity increases
– Protein disassembly begins
• Although digestion occurs in the stomach, nutrients are not absorbed
there.

21. Small intestines
• 90% of absorption occur in small intestines.

22. Small intestines
• Small intestine :
• Long : 6-7 m
• Diameter : 2.5 to 4 cm
• 4. Has 3 parts :
A. Duodenum :
• Located in Retroperitoneal space
• Long : 25cm
• Curves around the head of the pancreas
• Has Hepato-pancreatic ampula insert into Duodenum by Duodenal papilla
• Hepato-pancreatic ampula is a common pathway of Bile & Pancreatic juice
• Hepato-pancreatic ampula has a Sphincter called Hepato-pancreatic Sphincter

23. Small intestines
• B. Jejunum :
• Located in the intraperitoneal space
• Above 2.5 m
• Between Duodenum & Ileum
• C. Ileum :
• Located in the intraperitoneal space
• Above 3.6 m
• Between Jejunum & Cecum
• Ileum connect to Cecum is called Ileocecal valve ( sphincter )

24. Small intestines
• Mucosa
• Submucosa
• Muscularis Externa
• Serosa or advantitia

26. Small intestines

27. Liver
• Liver is the biggest organ
number 2 in human body.
• Liver weigh is 1,4kg which
lies at the upper right
abdomen.
• Liver is a complex organ.
• The functional unit of liver
is Lobule(Hexagona).

28. Liver
The liver consists of 4 distinct lobes – the left, right, caudate, and quadrate
lobes.
• The left and right lobes are the largest lobes and are separated by the falciform
ligament. The right lobe is about 5 to 6 times larger than the tapered left lobe.
• The small caudate lobe extends from the posterior side of the right lobe and
wraps around the inferior vena cava.
• The small quadrate lobe is inferior to the caudate lobe and extends from the
posterior side of the right lobe and wraps around the gallbladder.

29. • Liver is divided into 8 segments : I, II, III, IV,V,VI,VII,VIII
• Hilum of the Liver = Porta hepatis :
•  Hepatic Portal vein ( collected blood of the abdominalorgan: to
distribution and neutralization.
•  Hepatic artery ( branch of Celiac trunk ) : supply Liver
•  Common hepatic duct :bile pathway

30. Liver

31. Functions of the liver
1-Digestion
2-Metabolism
3-Detoxification
4-Storage
5-production
6-Immunity

32. Gall bladder
Thin-walled green muscular sac about 10 cm long ( size of Kiwi fruit )
 Located inferior to the right lobe of the liver
 It stores bile that is not immediately needed for digestion
 Too much Cholesterol >>> forming Gallstones or Biliary calculi >>
Obstruct the flow of bile from gallbladder >>> Pain >>> radiates to the
right thoracic region.

33. Gall bladder

34. Bile
Produced by cells in the liver
Composition
Bile salts
Bile pigment (mostly bilirubin from the breakdown of hemoglobin)
Cholesterol
Phospholipids
Electrolytes

35. Pancreas
• Largest gland in the body
• Located on the right side of the body under the diaphragm
 Connected to the gall bladder via the common hepatic duct
 Consist of four lobe:
1 head
2 neck
3 body
4 tail

36. Pancreas
It is the mixt gland :
1. Exocrine gland :
 Produce Pancreatic juice 1200 ml >>> 1500 ml / day ( pH : 8 )
 Pancreatic juice : water + Enzymes + electrolytes ( bicarbonate ions +++ )
 Pancreatic juice helps neutralize the Acidic chyme
2. Endocrine gland :
 Alpha-islet of Langerhans produces : Glucagon >> increases blood glucose (glycemia)
 Beta-islet of Langerhans produces : Insulin >>> reduces blood glucose ( glycemia)

37. pancreas

38. Large intestine
• Extends from ileocecal valve to Anus
• Diameter : 7 cm
• Long : 1.5 m
• Major Functions :
Absorb most of the remaining water from indigestible food residues
Store the residues temporarily
Eliminate them from body as semisolid Feces
It also absorbs metabolites produced by resident bacteria

39. Large intestine
The sigmoid colon connects Rectum at level of vetebral column S3
• Rectum has 3 rectal valves ( These valves stop feces from being passed along
with gas
• Anal canal is the last segment of the large intestine ( above 3 cm )
• Anal canal opens to the body exterior at the Anus
Anal canal has 2 sphincters
 Internal anal sphincter (composed of smooth muscle)
External anal sphincter ( composed of skeletal muscle )

40. Large intestine

41. Large intestine
• The colon has several regions :
 Ascending colon
 Right colic ( hepatic ) flexure
 Transverse colon
 Left colic ( splenic ) flexure
 Descending colon ( when enters the pelvis >> become S-shape = sigmoid colon )
• the colon is in Retroperitoneal space, except Transverse colon & Sigmoid colon
• Transverse colon & Sigmoid colon are in the intraperitoneal space & anchored to the posterior
abdominal wall by mesentery sheets called Mesocolons

42. Large intestine

43. Large intestine

44. 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 external surface most od
abdominal organ.
* The space between them contain fluid and called peritoneal
cavity this cavity may be accumulated by several liters of fluid
state called ascites

45. Peritoneum
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 theduodenum

47. Peritoneum

48. Nerve inervation

49. Nerve innervation