Download Histology Ass. Lec. Dentistry College Lab-7

Histology
Lab-7-
Ass. Lec.
Wafaa H. M. Alhashimy
Dentistry College
Second Stage
Digestive system : oral cavity , salivary glands ,esophagus
and stomach
The digestive system is long , hollow tube or tract that starts at the oral
cavity and terminates at the anus . the system consists of the oral cavity ,
esophagus , stomach , small intestine , large intestine , rectum and
anal canal . associated with the digestive tract are the accessory digestive
organs : the salivary glands , liver and pancreas .
The oral cavity
In the oral cavity , food is ingested , masticated (chewed ) and
lubricated by saliva for swallowing . because food is physically broken
down in the oral cavity , this region is lined by a protective , non
keratinized , stratified sequamous epithelium .
The lip
-The outer region is thin skin a stratified sequamous keratinized
epithelium contains hair follicles , sebaceous glands and sweat glands.
-The intermediate region (free margin) of the lip coverd the a stratified
sequamous non keratinized and the inner are contain skeletal muscle,
blood vessls are closed to the lip surface and impart a red color to the lips
- Inside region a stratified sequamous non keratinized oral epithelium ,
beneath the oral epithelium are mucus - secreting labial glands.
The tongue
Outer layer is the mucosa composet of epithelium and lamina properia
(loose C.T.)
The epithelium on the ventral surface of the tongue is smooth , the
epithelium on the dorsal surface of the tongue is irregular or rough
because contain numerous papillae
The core of the tongue consists of connective tissue and interlacing
bundles of skeletal muscle fibers are random distribution of individual
skeletal muscle fibers in the tongue for increased movement during
chewing , swallowing and speaking .
The posterior one third of the dorsal surface of the tongue is separated
from the anterior two thirds by the V-shaped sulcus terminalis.
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Type of papillae Tongue
All papillae on the tongue are coverd by stratified seaquamous
epithelium that shows partial or incomplete keratinization . there are four
types of papillae are found on the tongue :
filiform : most numerous , smollest , elongated conical shape, found in
rows parallel to the median sulcus but do not contain taste buds.
fungiform : fewer in number than filiform , larger , mushroom shaped
and contain a few taste buds on their , most numerous near the tip of the
tongue.
circumvallate : largest papillae , surrounded by a deep, circular furrow,
located along the sulcus terminalis and number from 7-12. Contain
Taste buds are located in its lateral surface. Numerous ducts of Serous
Ebner's glands drain a watery fluid containing lipases .
foliate : poorly developed in humans .
Taste buds
are pale, barrel-shaped intraepithelial bodies that extend from the basal
lamina to the surface.three type of cell found in taste bud including a
neuroepithelial cell (taste cell ) , support cells and basal cells (stem cell).
The taste buds have a small opening, called the taste pore, receive
innervation at their base.
The major salivary glands
There are three major salivary glands : the parotid (purely serous
gland), the submandibular (mixed gland serous & mucous) and the
sublingual(mixed gland serous & mucous) . salivary glands are composed
of cellular secretory units , tubuloacini and numerous excretory ducts
(intercalated Ducts , striated Ducts , Excretory intralobular Ducts ,
interlobular and interlobar Ducts) .
Esophagus
The layers of the oesophagus are as follows:


mucosa
o nonkeratinized stratified squamous epithelium: is rapidly
turned over, and serves a protective effect
o lamina propria:loose C.T.
o muscularis mucosae: smooth muscle .
submucosa: Denes irregular C.T., Contains the mucous secreting
glands (esophageal glands).
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

muscularis externa (or "muscularis propria"): composition varies in
different parts of the esophagus, to correspond with the conscious
control over swallowing in the upper portions and the autonomic
control in the lower portions:
o upper third, or superior part: striated muscle
o middle third, smooth muscle and striated muscle
o inferior third: predominantly smooth muscles
adventitia
Gastroesophageal junction
The junction between the esophagus and the stomach (the
gastroesophageal junction or GE junction) is not actually considered a
valve, although it is sometimes called the cardia or cardias.
Stomach
The three histologic regions of the stomach are the cardia , the fundus
and body and the pylorus. the stomach wall are:
mucosa
The first main layer. This consists of the epithelium and the lamina
propria (loose connective tissue), with a thin layer of smooth
muscle called the muscularis mucosae separating it from the
submucosa .
submucosa
consists of fibrous connective tissue, The Meissner's plexus is in
this layer .
the muscularis externa has three layers of smooth muscle instead
of two.

muscularis
externa


serosa
inner oblique layer: This layer is responsible physically
breaks down the food .
middle circular layer: the pylorus is surrounded by a thick
circular muscular wall ,which controls the movement of
chyme into the duodenum. Auerbach's plexus (myenteric
plexus) is found between the outer and middle layer.
outer longitudinal layer
consisting of layers of connective tissue continuous with the
peritoneum.
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Gastric glands
Different types of cells are found at gastric glands:
Layers of
Name
gland
parietal cells
Isthmus
Secretion
gastric acid and intrinsic factor, Acidophilic
Mucous neck
mucus gel layer
cells
fundus
chief cells
pepsinogen, Basophilic
enteroendocrine Defferent hormones to regulate digestive
fundus
cells
system as gastrin, histamine, and somatostatin
Rugae is temporary folded of the submucosa of stomach when the
stomach is empity formed when contraction of smooth muscle layer .
neck
Not:serosa covers lower esophagus , stomach ……to colon while
adventitia upper part of esophagus and posterior wall of colon.
stomach
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