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 gastroThe gastro
intestinal systemintestinal system
ByBy
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 intestineThe large intestine
 Accessory glands : salivary glands liverAccessory glands : salivary glands liver
pancreasespancreases

4. The basic layers of theThe basic layers of the
G.I.TG.I.T
 The mucosa: it is the inner layer formedThe 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 differentSchematic 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 ofLining epithelium made of
simple columnar epitheliumsimple columnar epithelium
It sits on a basementIt sits on a basement
membranemembrane
Lamina propria made of looseLamina propria made of loose
connective tissue bfull ofconnective tissue bfull of
macrophges and lymphocytesmacrophges and lymphocytes
Muscularis mucosae separateMuscularis mucosae separate
mucosa from submucosamucosa from submucosa
contraction of which leads tocontraction of which leads to
increase contact of epitheliumincrease contact of epithelium
with foodwith food

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

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

9. SerosaSerosa
 It is a layer of looseIt is a layer of loose
connective tissueconnective tissue
covered by a layer ofcovered by a layer of
simple squamoussimple squamous
epithelium calledepithelium called
mesotheliummesothelium
 It contains theIt contains the
lymphatic and bloodlymphatic and blood
vessels of the GI tractvessels of the GI tract
and fat tissueand fat tissue

10. Oral cavityOral cavity
 Is lined with stratified squamousIs lined with stratified squamous
epithelium to protect the mouthepithelium 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 withlips, and cheeks are lined with
non-keratinized epitheliumnon-keratinized epithelium
 Lamina propria contains manyLamina 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 ofIt 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 foodThe 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 nonThe mucosa: formed of stratified squamuse non
keratinized epitheliumkeratinized epithelium
 The sub mucosa: formed of loose tissue contain bloodThe 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 collagenThe serosa: formed of deep fascia formed of collagen
fibersfibers

12. The esophagusThe esophagus
 It is muscular tube extend from theIt is muscular tube extend from the
pharynx to the stomach passes throughpharynx 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 stratifiedLining 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 histologicalThe histological
structure of thestructure of the
esophagusesophagus The mucosa: the epithelium formed of stratifiedThe mucosa: the epithelium formed of stratified
squamuse non keratinized epithelium this epitheliumsquamuse non keratinized epithelium this epithelium
rich in mucus cellsrich in mucus cells
 The lamina proporia: formed of collagen fibers rich inThe 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 isThe muscularis mucosa: formed of smooth muscle it is
function conduction of the gland secretionfunction conduction of the gland secretion
 The sub mucosa: formed of areolar tissue containThe 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 smoothThe musculosa: formed of two layers of smooth
muscle inner circular and outer longitudinalmuscle inner circular and outer longitudinal
 The serosa: formed of deep fascia in the neck and heThe serosa: formed of deep fascia in the neck and he
chest but by mesothelium in the abdomenchest but by mesothelium in the abdomen

16. Esophagus (crossEsophagus (cross
sectionsection((

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

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 histologicalThe histological
structure of thestructure of the
stomachstomach
 The mucosa: the epithelium formed of simpleThe mucosa: the epithelium formed of simple
columnar ciliated epithelium. It is folded and formedcolumnar ciliated epithelium. It is folded and formed
the gastric glands which open in the surface bythe 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 otherThe stem cell : it is function divided and gives other
types of cellstypes of cells

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

23. The sub mucosaThe sub mucosa
 It is formed of loose connective tissueIt 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 whichThe 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 structureHistological structure
of stomachof stomach

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

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

29. The duodenumThe duodenum
 It is the first part of the small intestineIt 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 duodenumThe 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 materialsAbsorption of nutrient materials

30. The histologicalThe histological
structure of thestructure of the
duodenumduodenum
 The mucosa: the epithelium formed ofThe mucosa: the epithelium formed of
simple columnar ciliated epithelium itsimple columnar ciliated epithelium it
forms finger like projection called the villiforms finger like projection called the villi
the spaces between them called cryptsthe spaces between them called crypts
 The lamina proporia: collagen fibers toThe lamina proporia: collagen fibers to
support the mucosasupport the mucosa
 Muscularis mucosa: smooth muscle andMuscularis 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 itIt is formed of loose connective tissue it
contain blood vessels, nerve fibers andcontain blood vessels, nerve fibers and
lymphatic tissue also it contain seriouslymphatic tissue also it contain serious
glandsglands
 The musculosa: formed of tow layers ofThe musculosa: formed of tow layers of
smooth muscles inner circular and outersmooth muscles inner circular and outer
longitudinallongitudinal
 The serosa: formed of mesotheliumThe serosa: formed of mesothelium

34. The duodenumThe duodenum

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

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

37. The large intestineThe large intestine
 The large intestine formed of theThe 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 theThe function of the
large intestinelarge intestine
 The absorption of waterThe absorption of water
 Excluded of the waste productExcluded of the waste product

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

40. The lamina proporiaThe lamina proporia
 It formed of collagen fibers rich in blood vessels andIt 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 glandmuscle 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 lymphaticcontain blood vessel, nerve fibers, and lymphatic
tissuetissue
 The musculosaThe musculosa: formed of two layers of smooth: formed of two layers of smooth
muscle inner circular and outer longitudinal. Themuscle inner circular and outer longitudinal. The
longitudinal muscle collected into bands called tenalongitudinal muscle collected into bands called tena
collicolli
 The serosaThe serosa: formed of mesothelium: formed of mesothelium

41. Large intestineLarge 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 theIt is function to give passage for the
feces out side the bodyfeces out side the body

43. The histological structureThe 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 partlined by simple columnar while the middle part
lined by stratified squamus non keratinizedlined 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 mucosafibers 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 andcontain blood vessel, nerve fibers and
lymphaticlymphatic

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

47. The liver functionsThe liver functions
 The blood reach the liver through the portal veinThe blood reach the liver through the portal vein
which is carry non oxygenated blood from intestinewhich 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 anglesThese vessels divided and finally reach the angles
of the hepatic lobule, then the blood passes in theof the hepatic lobule, then the blood passes in the
sinusoid where the hepatic cells perform theresinusoid 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 bileThe 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 isThe hepatic cells: they are cubical in shape. It is
double nucleated cells active cellsdouble nucleated cells active cells

48. Shape of the liverShape of the liver

49. Histological structureHistological structure
of the liverof the liver
 The liver is formed ofThe 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 ofliver 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 bloodis formed of the hepatocytes and blood
sinusoid and bile canaliculisinusoid and bile canaliculi
 The hepatocytes arranged into rows andThe hepatocytes arranged into rows and
formed hexunal shape called hepatic lobuleformed hexunal shape called hepatic lobule

50. Cross section (liver(

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

52. Hepatic lobuleHepatic lobule

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

54. pancreaspancreas

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

56. Histological structure ofHistological structure of
pancreaspancreas