The gastro intestinal system

study of structures and functions of the gastrointestinal tract
- histology of the oral cavity
- histology of the pharynx
- histology of the esophagus and stomach
- histology of intestine
- histology of the liver and pancreas

1. The gastro The gastro
intestinal systemintestinal system
By By
Dr. Mohammed Ahamed AbuelnorDr. Mohammed Ahamed Abuelnor

2. Functions of the GITFunctions of the GIT
Transport and food digestionTransport and food digestion
Absorption of foodAbsorption of food
Secretion of hormones and enzymes of digestionSecretion of hormones and enzymes of digestion
Production of mucus for lubrication of ingested foodProduction of mucus for lubrication of ingested food

3. The parts G.I.TThe parts G.I.T
Parts of the G.I.T are :-Parts of the G.I.T are :-
Elmantry canal formed of :-Elmantry canal formed of :-
Oral cavityOral cavity
The pharynxThe pharynx
The esophagusThe esophagus
The stomachThe stomach
The small intestineThe small intestine
The large intestine The large intestine
Accessory glands : salivary glands liver Accessory glands : salivary glands liver
pancreases pancreases

4. The basic layers of the The basic layers of the
G.I.TG.I.T
The mucosa: it is the inner layer formed The mucosa: it is the inner layer formed
ofof
EpitheliumEpithelium
Lamina proporiaLamina proporia
Muscularis mucosaMuscularis mucosa
The sub mucosaThe sub mucosa
The musculosaThe musculosa
The serosaThe serosa

5. Histology of GITHistology of GIT
Schematic diagram showing different Schematic diagram showing different
layers of GITlayers of GIT
1.1.MucosaMucosa
2.2.SubmucosaSubmucosa
3.3.MuscularisMuscularis
4.4.SerosaSerosa

6. MucosaMucosa
Consists of:Consists of:
Lining epithelium made of Lining epithelium made of
simple columnar epitheliumsimple columnar epithelium
It sits on a basement It sits on a basement
membrane membrane
Lamina propria made of loose Lamina propria made of loose
connective tissue bfull of connective tissue bfull of
macrophges and lymphocytesmacrophges and lymphocytes
Muscularis mucosae separate Muscularis mucosae separate
mucosa from submucosa mucosa from submucosa
contraction of which leads to contraction of which leads to
increase contact of epithelium increase contact of epithelium
with foodwith food

7. SumucosaSumucosa
Consists of a layer of Consists of a layer of
dense connective dense connective
tissuetissue
Rich in blood vessels Rich in blood vessels
Contains submucosal Contains submucosal
nerve plexusesnerve plexuses
Some times it may Some times it may
contain mucus glandscontain mucus glands

8. MuscularisMuscularis
Generally, it consists of Generally, it consists of
two layers of smooth two layers of smooth
muscle fibersmuscle fibers
Inner circular and outer Inner circular and outer
longitudinallongitudinal
Myenteric nerve Myenteric nerve
plexuses are distributed plexuses are distributed
between the two muscle between the two muscle
layerslayers
With the submucosal With the submucosal
nerve plexuses, they nerve plexuses, they
help propel and mixing help propel and mixing
the foodthe food

9. SerosaSerosa
It is a layer of loose It is a layer of loose
connective tissue connective tissue
covered by a layer of covered by a layer of
simple squamous simple squamous
epithelium called epithelium called
mesotheliummesothelium
It contains the It contains the
lymphatic and blood lymphatic and blood
vessels of the GI tract vessels of the GI tract
and fat tissueand fat tissue

10. Oral cavityOral cavity
Is lined with stratified squamous Is lined with stratified squamous
epithelium to protect the mouth epithelium to protect the mouth
from the effect of foodfrom the effect of food
Soft palate, floor of the mouth, Soft palate, floor of the mouth,
lips, and cheeks are lined with lips, and cheeks are lined with
non-keratinized epitheliumnon-keratinized epithelium
Lamina propria contains many Lamina propria contains many
diffuse salivary glandsdiffuse salivary glands

11. The pharynxThe pharynx
It is the part of the G.I.T which extend from the base of It is the part of the G.I.T which extend from the base of
the skull to the esophagusthe skull to the esophagus
The function of the pharynx is the swalling of the food The function of the pharynx is the swalling of the food
The histological structure of the pharynxThe histological structure of the pharynx
The mucosa: formed of stratified squamuse non The mucosa: formed of stratified squamuse non
keratinized epitheliumkeratinized epithelium
The sub mucosa: formed of loose tissue contain blood The sub mucosa: formed of loose tissue contain blood
vessels, nerve fibers and lymphatic tissuevessels, nerve fibers and lymphatic tissue
The musculosa: formed of skeletal muscleThe musculosa: formed of skeletal muscle
The serosa: formed of deep fascia formed of collagen The serosa: formed of deep fascia formed of collagen
fibers fibers

12. The esophagusThe esophagus
It is muscular tube extend from the It is muscular tube extend from the
pharynx to the stomach passes through pharynx to the stomach passes through
the neck, the chest, and the abdomenthe neck, the chest, and the abdomen
It is function is the swalling of the foodIt is function is the swalling of the food

13. EosophagusEosophagus
Consists of four layersConsists of four layers
Lining epithelium is stratified Lining epithelium is stratified
squamous non-keratinizedsquamous non-keratinized
Eosophageal submucus glandEosophageal submucus gland
Eosopageal cardiac glandsEosopageal cardiac glands
Muscular layerMuscular layer
Covering serosa and adventitiaCovering serosa and adventitia
Parts of the esophagusParts of the esophagus
Upper partUpper part
Middle partMiddle part
Lower partLower part

14. esophagusesophagus

15. The histological The histological
structure of the structure of the
esophagusesophagus The mucosa: the epithelium formed of stratified The mucosa: the epithelium formed of stratified
squamuse non keratinized epithelium this epithelium squamuse non keratinized epithelium this epithelium
rich in mucus cellsrich in mucus cells
The lamina proporia: formed of collagen fibers rich in The lamina proporia: formed of collagen fibers rich in
blood vessels support the mucosa to the sub mucosablood vessels support the mucosa to the sub mucosa
The muscularis mucosa: formed of smooth muscle it is The muscularis mucosa: formed of smooth muscle it is
function conduction of the gland secretion function conduction of the gland secretion
The sub mucosa: formed of areolar tissue contain The sub mucosa: formed of areolar tissue contain
blood vessels, lymphatic, and nerve fibersblood vessels, lymphatic, and nerve fibers
The musculosa: formed of two layers of smooth The musculosa: formed of two layers of smooth
muscle inner circular and outer longitudinal muscle inner circular and outer longitudinal
The serosa: formed of deep fascia in the neck and he The serosa: formed of deep fascia in the neck and he
chest but by mesothelium in the abdomen chest but by mesothelium in the abdomen

16. Esophagus (cross Esophagus (cross
sectionsection((

17. The stomachThe stomach
Definition: it is the most dilated part of the Definition: it is the most dilated part of the
G.I.T. organsG.I.T. organs
It is function is the digestion of food by It is function is the digestion of food by
two methodstwo methods
Mechanical digestion: by the thick wall of Mechanical digestion: by the thick wall of
the stomachthe stomach
Chemical digestion: by the secretion of Chemical digestion: by the secretion of
enzymes enzymes

18. Parts of stomachParts of stomach
The stomach formed of four parts:The stomach formed of four parts:
The cardiacThe cardiac
The fundsThe funds
The bodyThe body
The pyloricThe pyloric

20. The stomachThe stomach

21. The histological The histological
structure of the structure of the
stomachstomach
The mucosa: the epithelium formed of simple The mucosa: the epithelium formed of simple
columnar ciliated epithelium. It is folded and formed columnar ciliated epithelium. It is folded and formed
the gastric glands which open in the surface by the gastric glands which open in the surface by
gastric pitsgastric pits
The types of epithelial cellsThe types of epithelial cells
The mucus cells: it is function secretion of mucusThe mucus cells: it is function secretion of mucus
The parietal cells: it is function secretion of HCLThe parietal cells: it is function secretion of HCL
The peptic cell: it is function secretion of pepsinThe peptic cell: it is function secretion of pepsin
The stem cell : it is function divided and gives other The stem cell : it is function divided and gives other
types of cells types of cells

22. The lamina proporiaThe lamina proporia
It is formed of collagen fibers and it rich It is formed of collagen fibers and it rich
in blood vessels, nerve fibers in blood vessels, nerve fibers
It is function to support the mucosaIt is function to support the mucosa
The musularis mucosa: it is formed of The musularis mucosa: it is formed of
sheet of smooth muscle it is function is sheet of smooth muscle it is function is
the conduction of the gastric secretion the conduction of the gastric secretion

23. The sub mucosaThe sub mucosa
It is formed of loose connective tissue It is formed of loose connective tissue
which contain blood vessel , nerve fibers, which contain blood vessel , nerve fibers,
and lymphatic tissueand lymphatic tissue
The nerve fibers formed plexuses which The nerve fibers formed plexuses which
is called the missioner's plexusesis called the missioner's plexuses

24. The musculosaThe musculosa
It is thick and formed of three layersIt is thick and formed of three layers
Inner obliqueInner oblique
Middle circularMiddle circular
Outer longitudinalOuter longitudinal

25. Histological structure Histological structure
of stomachof stomach

26. The serosaThe serosa
It is formed of mesothelium It is formed of mesothelium
(simple squamuse epithelium) of the (simple squamuse epithelium) of the
inner layer of the peritoneum inner layer of the peritoneum

27. The different between The different between
the parts of the the parts of the
stomachstomach
All the parts of stomach have the same All the parts of stomach have the same
histological structure except in the histological structure except in the
following:following:
The pyloric part has branches gastric The pyloric part has branches gastric
glands and wide gastric pitsglands and wide gastric pits
The funds and the body have rich The funds and the body have rich
parietal cells than the pyloricparietal cells than the pyloric
The pyloric has much mucus cells The pyloric has much mucus cells

28. The small intestineThe small intestine
The small intestine formed of three partsThe small intestine formed of three parts
The duodenumThe duodenum
The jejunumThe jejunum
The ileum The ileum

29. The duodenumThe duodenum
It is the first part of the small intestine It is the first part of the small intestine
extend from the stomach to the jejunumextend from the stomach to the jejunum
The function of the duodenum The function of the duodenum
Neutralization of the gastric acidityNeutralization of the gastric acidity
Continues the process of digestionContinues the process of digestion
Absorption of nutrient materials Absorption of nutrient materials

30. The histological The histological
structure of the structure of the
duodenumduodenum
The mucosa: the epithelium formed of The mucosa: the epithelium formed of
simple columnar ciliated epithelium it simple columnar ciliated epithelium it
forms finger like projection called the villi forms finger like projection called the villi
the spaces between them called crypts the spaces between them called crypts
The lamina proporia: collagen fibers to The lamina proporia: collagen fibers to
support the mucosasupport the mucosa
Muscularis mucosa: smooth muscle and Muscularis mucosa: smooth muscle and
extend deep in the villiextend deep in the villi

33. The sub mucosaThe sub mucosa
It is formed of loose connective tissue it It is formed of loose connective tissue it
contain blood vessels, nerve fibers and contain blood vessels, nerve fibers and
lymphatic tissue also it contain serious lymphatic tissue also it contain serious
glandsglands
The musculosa: formed of tow layers of The musculosa: formed of tow layers of
smooth muscles inner circular and outer smooth muscles inner circular and outer
longitudinallongitudinal
The serosa: formed of mesothelium The serosa: formed of mesothelium

34. The duodenumThe duodenum

35. The jejunum and ileumThe jejunum and ileum
The jejunum formed the upper part of the The jejunum formed the upper part of the
small intestine while the ileum formed the small intestine while the ileum formed the
lower part lower part
The function of the jejunum and ileum The function of the jejunum and ileum
absorption of nutrient substanceabsorption of nutrient substance

36. The histological The histological
structure of the structure of the
jejunum and ileumjejunum and ileum
The jejunum has the same histological The jejunum has the same histological
structure of the duodenum but the structure of the duodenum but the
lymphatic tissues in the sub mucosa lymphatic tissues in the sub mucosa
increased and formed aggregations of increased and formed aggregations of
lymph called peyer,s patches and the villi lymph called peyer,s patches and the villi
become longerbecome longer
The ileum has the same histological The ileum has the same histological
structure but the lymph and the mucus structure but the lymph and the mucus
cells increased cells increased

37. The large intestineThe large intestine
The large intestine formed of the The large intestine formed of the
following organs:following organs:
The cecaumThe cecaum
The colonThe colon
The rectumThe rectum
The anal canalThe anal canal

38. The function of the The function of the
large intestinelarge intestine
The absorption of waterThe absorption of water
Excluded of the waste productExcluded of the waste product

39. The histological The histological
structure of the large structure of the large
intestineintestine
TheThe mucosamucosa: the epithelium formed of : the epithelium formed of
simple columnar ciliated epithelium which simple columnar ciliated epithelium which
is folded and formed straight glandsis folded and formed straight glands
 the epithelium cell formed of two types the epithelium cell formed of two types
mucus cellsmucus cells for secretion of mucus and for secretion of mucus and
brush cellsbrush cells for absorption of water the for absorption of water the
mucus cells increas and the brush cells mucus cells increas and the brush cells
decrease toward the anal canal decrease toward the anal canal

40. The lamina proporiaThe lamina proporia
It formed of collagen fibers rich in blood vessels and It formed of collagen fibers rich in blood vessels and
peyer,s patchespeyer,s patches
TheThe muscularismuscularis mucosamucosa: formed of sheet of smooth : formed of sheet of smooth
muscle it is function the conduction of the gland muscle it is function the conduction of the gland
secretionsecretion
TheThe subsub mucosamucosa: formed of loose areolar tissue : formed of loose areolar tissue
contain blood vessel, nerve fibers, and lymphatic contain blood vessel, nerve fibers, and lymphatic
tissue tissue
The musculosaThe musculosa: formed of two layers of smooth : formed of two layers of smooth
muscle inner circular and outer longitudinal. The muscle inner circular and outer longitudinal. The
longitudinal muscle collected into bands called tena longitudinal muscle collected into bands called tena
colli colli
The serosaThe serosa: formed of mesothelium : formed of mesothelium

41. Large intestine Large intestine
(cross section(cross section((

42. The anal canalThe anal canal
DefinitionDefinition: it is the lower part of the large : it is the lower part of the large
intestineintestine
It is function to give passage for the It is function to give passage for the
feces out side the body feces out side the body

43. The histological structure The histological structure
of the anal canalof the anal canal
The mucosaThe mucosa: the upper part of the anal canal : the upper part of the anal canal
lined by simple columnar while the middle part lined by simple columnar while the middle part
lined by stratified squamus non keratinized lined by stratified squamus non keratinized
epithelium and the lower part lined by skinepithelium and the lower part lined by skin
The mucosa fold and formed the anal columnsThe mucosa fold and formed the anal columns
The lamina proporiaThe lamina proporia: formed of collagen : formed of collagen
fibers support the mucosa fibers support the mucosa
The sub mucosaThe sub mucosa: it is formed of loose tissue : it is formed of loose tissue
contain blood vessel, nerve fibers and contain blood vessel, nerve fibers and
lymphatic lymphatic

44. The musculosaThe musculosa
It is formed of inner circular layer which is It is formed of inner circular layer which is
thick at the lower part and outer thick at the lower part and outer
longitudinal layer. There is skeletal longitudinal layer. There is skeletal
muscles cover the outer longitudinal muscles cover the outer longitudinal
layerlayer
The serosaThe serosa: formed of connective tissue : formed of connective tissue
to support the anal canal with the to support the anal canal with the
surrounded tissue surrounded tissue

45. Anal canalAnal canal

46. The liverThe liver
DefinitionDefinition : the liver is the largest gland in : the liver is the largest gland in
the body it is located in the right side of the the body it is located in the right side of the
abdomenabdomen
The functions of the liverThe functions of the liver::
Detoxification of metabolic waste productDetoxification of metabolic waste product
Destruction of the span red blood cellsDestruction of the span red blood cells
Syntheses of the bileSyntheses of the bile
Syntheses of the plasma proteinsSyntheses of the plasma proteins
Metabolic functions Metabolic functions

47. The liver functionsThe liver functions
The blood reach the liver through the portal vein The blood reach the liver through the portal vein
which is carry non oxygenated blood from intestine which is carry non oxygenated blood from intestine
.and the hepatic artery which carry oxygenated .and the hepatic artery which carry oxygenated
blood.blood.
These vessels divided and finally reach the angles These vessels divided and finally reach the angles
of the hepatic lobule, then the blood passes in the of the hepatic lobule, then the blood passes in the
sinusoid where the hepatic cells perform there sinusoid where the hepatic cells perform there
function and drainage in the central vein.function and drainage in the central vein.
The bile secreted by the hepatic cells in the bile The bile secreted by the hepatic cells in the bile
canals where it collect in the bile ductcanals where it collect in the bile duct
The hepatic cells: they are cubical in shape. It is The hepatic cells: they are cubical in shape. It is
double nucleated cells active cells double nucleated cells active cells

48. Shape of the liverShape of the liver

49. Histological structure Histological structure
of the liverof the liver
The liver is formed of The liver is formed of
StromaStroma: which is the capsule that covered the : which is the capsule that covered the
liver and fixed and protect it. It is formed of liver and fixed and protect it. It is formed of
collagen fiberscollagen fibers
The parenchymaThe parenchyma: which is tissue of the liver it : which is tissue of the liver it
is formed of the hepatocytes and blood is formed of the hepatocytes and blood
sinusoid and bile canaliculisinusoid and bile canaliculi
The hepatocytes arranged into rows and The hepatocytes arranged into rows and
formed hexunal shape called hepatic lobule formed hexunal shape called hepatic lobule

50. Cross section (liver(

51. The hepatic lobuleThe hepatic lobule
Definition:Definition: it is the functional unite of the it is the functional unite of the
liver. It is hexanal shapeliver. It is hexanal shape
It is formed of six angles in each one It is formed of six angles in each one
contain branch of portal vein, hepatic artery, contain branch of portal vein, hepatic artery,
and bile duct. In the center it contain central and bile duct. In the center it contain central
vein.vein.
Between the center and the angle the Between the center and the angle the
hepatic cells arranged into rows which are hepatic cells arranged into rows which are
separated by blood sinusoid. In the middle separated by blood sinusoid. In the middle
of each row there is bile canal of each row there is bile canal

52. Hepatic lobuleHepatic lobule

53. The pancreasThe pancreas
Definition: it is lobulated mixed gland Definition: it is lobulated mixed gland
located at the concavity of the duodenumlocated at the concavity of the duodenum
The pancreas has exocrine secretion for The pancreas has exocrine secretion for
the digestion of the carbohydrate and it is the digestion of the carbohydrate and it is
endocrine secretion for control of the endocrine secretion for control of the
blood glucose blood glucose

54. pancreaspancreas

55. The histological structure The histological structure
of the pancreasof the pancreas
The pancreas enclosed by thin capsule formed of The pancreas enclosed by thin capsule formed of
collagen fibers. From the capsule thin septa collagen fibers. From the capsule thin septa
descend and divided the parenchyma into lobes descend and divided the parenchyma into lobes
The parenchyma formed of tubules surrounded by The parenchyma formed of tubules surrounded by
cells these tubules called the pancreatic acini . The cells these tubules called the pancreatic acini . The
pancreatic acini drainage at the main pancreatic pancreatic acini drainage at the main pancreatic
duct which open at the duodenumduct which open at the duodenum
Between the pancreatic acini there is dark cells Between the pancreatic acini there is dark cells
which are the endocrine cells of the pancreas called which are the endocrine cells of the pancreas called
islet of langerhanes islet of langerhanes

56. Histological structure of Histological structure of
pancreaspancreas