Transcript Gastric gland contains the following cells

Gastrointestinal
Tract
 1.
Gastrointestinal Tract(oral cavity
till anal orifice).
 2. Assosciated Glands.
 Oral Cavity
 Within the oral cavity are the
tongue, teeth and the salivary
glands ,which empty their secretory
products into the oral cavity.
Histology of GIT
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Schematic diagram showing different layers of
GIT
1.
Mucosa
Submucosa
Muscularis
Serosa
2.
3.
4.
Mucosa
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Consists of:
Lining epithelium made of
simple columnar epithelium
It sits on a basement
membrane
Lamina propria made of loose
connective tissue bfull of
macrophges and lymphocytes
Muscularis mucosae separate
mucosa from submucosa
contraction of which leads to
increase contact of epithelium
with food
Sumucosa
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Consists of a layer of
dense connective tissue
Rich in blood vessels
Contains submucosal
nerve plexuses
Some times it may
contain mucus glands
Muscularis
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Generally, it consists of two
layers of smooth muscle
fibers
Inner circular and outer
longitudinal
Myenteric nerve plexuses
are distributed between
the two muscle layers
With the submucosal
nerve plexuses, they help
propel and mixing the food
Serosa
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It is a layer of loose
connective tissue
covered by a layer of
simple squamous
epithelium called
mesothelium
It contains the lymphatic
and blood vessels of the
GI tract and fat tissue
Functions of the GIT
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Selective permeability
Transport and food digestion
Absorption of food
Secretion of hormones and enzymes of digestion
Production of mucus for lubrication and moisturizing
ingested food
Immunity
The epithelial lining is divided into
two types:
 1.Masticatory epithelium covers
(tongue, gingivae and hard palate).
The epithelium is keratinized
stratified squamous epithelium.
 2.Lining epithelium, i.e. nonkeratinised stratified squamous
epithelium, covers the remaining
surfaces of the oral cavity.
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Oral cavity
 Is
lined with stratified squamous
epithelium to protect the mouth
from the effect of food
 Soft palate, floor of the mouth, lips,
and cheeks are lined with nonkeratinized epithelium
 Lamina propria contains many
diffuse salivary glands
The Tongue
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It consists of skeletal muscle
fibers concerned with change
in tongue shape
The tongue is attaches to
nearby bony structures to
move the tongue in various
directions
It is covered by different types
of papillae
Tongue Papillae
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They are four types:
Filliform
Fungiform
Circumvallate
Foliate
With the exception of
filiform, they contain taste
buds for taste sensation
Taste bud consists of
sensory cells, supporting
cells, and basal cells
Von Ebner glands
 Lingual
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Papilla
Papillae are elevations of the oral
epithelium and lamina propria that assume
various forms and functions.
Filiform papillae have an elongated conical
shape; they are quite numerous and are
present over the entire surface of the
tongue. Their epithelium, which does not
contain taste buds, is keratinized.
Fungiform papillae resemble
mushrooms.These papillae, which contain
scattered taste buds on their upper
surfaces, are irregularly interspersed
among the filiform papillae.
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Foliate papillae are poorly developed in
humans. They consist of two or more
parallel ridges and furrows on the
dorsolateral surface of the tongue and
contain many taste buds.
Circumvallate papillae are 7–12 extremely
large circular papillae whose flattened
surfaces extend above the other papillae.
They are distributed in the V region in the
posterior portion of the tongue. Numerous
serous (von Ebner's) glands drain their
contents into the deep groove that encircles
the periphery of each papilla
Taste
Buds
 Cells that form the taste bud can
functionally be divided into three groups:
Sensory cells,
Supporting (or sustentacular) cells
 Basal cells(regenerate the two other
cell types)
Taste buds are also found in the palate,
in the pharynx and larynx.
Teeth
There are 20 deciduous
teeth
 There are 32 permanent
teeth
 Each tooth consists of :
Enamel (ameloblasts)
Dentin(odontoblasts)
Pulp
Cementum(cementocytes
Periodontal ligament
Root canal
Gingiva
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Histology of GIT
Eosophagus
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Consists of four layers
Lining epithelium is stratified
squamous non-keratinized
Eosophageal submucus gland
Eosopageal cardiac glands
Muscular layer
Covering serosa and adventitia
Parts of the esophagus
Upper part
Middle part
Lower part
Stomach
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It is a mixed gland and
secretes hormones
Is divided histologically into
three parts:
Body and fundus: secrete HCL
Cardia: secretes mucus
Pyloric region: secretes mucus
Mucosa and submucosa are
found within rugae
Muscularis consists of three
layaers
Cardia contains simple or
branched tubular glands
Stomach Cont.
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Fundus and body contain branched tubular glands
3-7 opens into one pit
Gastric gland is divided into:
Gastric pit
Isthmus
Neck
Base
Stomach Cont.
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Gastric gland contains the
following cells:
Surface mucus
Stem cells
Mucus neck cells : mucus
Parietal (Oxyntic cells) : HCL
Chief cells : pepsinogen
Enteroendocrine cells : gastrin
and serotonin
Regions of the Stomach
Transition Zone between
Stomach and Duodenum
Small Intestine
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Consists of four layers
Mucosa
Lining epithelium is simple columnar ,lamina
propria containg intestinal glands & muscularis
mucosae
Submucosa(c.t)
In the duodenum there are submucosal glands
called Brunner’s glands
Muscular layer inner circular and outer
longitudinal.
Serosa (c.t and mesothelium)
Small intestine cont.
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Is the site of terminal digestion, absorption and
enteroendocrine secretion
Composed of Duodenum, Jejunum, Ileum
Plica circularsis mostly in jejunum composed of
mucosa and sumucosa increase the surface area 3
times
Intestinal villi leaf-like to tubular form composed of
epithelium and lamina propria
Intestinal glands (simple tubular)
Lined with absorbtive columnar cells
and goblet cells
Paneth cells
M cells
M
(microfold) cells are specialized
epithelial cells overlying the lymphoid
follicles of Peyer's patches.
 These cells are characterized by the
presence of intraepithelial lymphocytes
and antigen-presenting cells
(macrophages).
 M cells can endocytose antigens and
transport them to the underlying
macrophages and lymphoid cells,
Small Intestine Cont.,
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Intestinal glands (Crypt of Lieberkühn)
Are short tubular glands
Continuous with intestinal villi
Contain enteroendocrine cells and
Paneth cells
Absorptive epithelium
It has many microvilli (brush border)
and goblet cells
It contains stem cells that replace
other types of cells
Villi increase the surface area by 10
and microvilli and increase the surface
area by 20 time.
Regions of Small Intestine
Jejunum
Ileum and
Peyer’s patches
Duodenum and
Bruner’s glands
 Between
the intestinal villi we
see the openings of simple
tubular glands, the crypts of
Lieberkühn.They extend through
the lamina propria down to the
muscularis mucosae.
Undifferentiated cells close to
the bottom of the crypts
regenerate the epithelium.
Large Intestine
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No folds or villi
Abundance of goblet cells
Absorptive cells with irregular
microvilli
Stem cell in lower portion of
the glands
Few enteroendocrine cells
Lymph follicles
Taeniae coli
Appendices epiploicae
Appendix
It is a large intestine Except:
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Narrow, small, irregular lumen
Abundunt lymphoid follicles
Few and short glands
No teniae coli
Medical Application
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Congenital Pyloric Hypertrophy
Atrophic Gastritis
Peptic ulcer
Malabsorption syndrome
Megacolon
Appendicitis
Thank You
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