digestive glands
DESCRIPTION
Digestive glands. General outline. small digestive glands. distributed in the wall of digestive tract esophageal glands, gastric glands and intestine glands. large digestive glands. outside the wall of digestive tract salivary glands, liver and pancreas. Large salivary glands. - PowerPoint PPT PresentationTRANSCRIPT
Digestive glands
General outline
small digestive glands
distributed in the wall of digestive tract
esophageal glands, gastric glands and
intestine glands large digestive glands
outside the wall of digestive tract
salivary glands, liver and pancreas
Large salivary glands
Include parotid, submandibular and
sublingual glands
are compound tubuloacinar glands
are composed of acini and ducts
Acinus :
acinar epithelium: simple
cuboidal or pyramidal cells myoepithelial cell basal membrane
Structure:
Be divided into
Serous acini
Mucous acini
Mixed acini
Serous acini
cytoplasma are deep stained
nucleus are spherical in shape and near
the base
secretion is thin, contains salivary amylase
and a little mucus
Serous acini and striated duct
Mucous acini
cytoplasma are light-blue stained
nucleus are flattened ovoid shaped and
close to the base
secretion is thick; contains mucoprotein
Mucous acini
Mixed acini
consist of above two kinds of cells
demilunes: several serous cells are
attached eccentrically to the mucous acini
Mixed acini
Ducts:
Intercalated ducts
diameter: thinnest
wall: simple low cuboidal epithelium
Striated duct (secretory duct)
wall: simple columnar epithelium; the nucleus
is near the cell apex; cytoplasm is
acidpphilic; has basal striations
EM: the basal striations created by
membrane infolding and mitochondia
reabsorbing sodium and excreting potassium;
transport water and ions
Intercalated ducts and striated ducts
Interlobular duct
Wall: pseudostratified epithelium
Main duct
Near its orifice become stratified
squamous epithelium
Parotid gland
pure serous gland
longer intercalated duct
secrete 25% of saliva, more salivary
amylase, less mucus
Parotid gland
Submandibular gland
mixed gland. Serous acini are more than
mixed or mucous acini
short intercalated duct, longer striated duct
secrete 70% of saliva, less salivary amylase,
more mucus
Submandibular gland
Sublingual gland
mixed gland, mucous and mixed acini
predominant, more demilune
without intercalated duct, obscure striated
duct
secrete 5% of saliva, most mucus
Sublingual gland
Pancreas
Exocrine portion:
the features of the acini
a single layer of pyramidal serous cells
surrounded by basal lamina, without
myoepithelial cells
centro-acinar cells: the epithelial cells of
intercalated duct penetrating into the
lumen of the acinus
the feature of ducts
the intercalated duct is long and has branches
no striated duct
main duct: lined by simple columnar
epithelium in which a few goblet cells
and endocrine cells can be seen
The functions of exocrine portion
Secret abundant trypsinogen,
chymotrypsinogen, amylase, lipase,
sodium bicarbonate and trypsin inhibitor
Pancreas
Pancreas ( show centro-acinar cells and intercalated ducts)
Endocrine portion (pancreatic islet):
rounded clusters of cells embedded within
exocrine pancreatic tissue
are divided into three kinds of cells: A, B,
and D cells
fenestrated capillaries are among the
cells
Pancreas (show pancreatic islet)
Size number Distribution Function
A cells large 20% Peripheral glucagon
B cells small 75% center insulin
D cells 5%Among A
and B cellssomatostatin
Endocrine portion
Other cellsPP cells: pancreatic polypeptide
G cells: gastrin
A cells B cells
D cells
Liver
Liver lobule
Portal area
Hepatic plates
Sinusoid
Central vein
Interlobular arteries
Interlobular veins
Interlobular bile ducts
Functions of liver:
bile secretion
synthesize: protein, glycogen, cholesterin
detoxification and inactivation
defence
hemopoiesis
Human liver
Pork liver
Liver lobule:
hepatic plates: are composed of a single
layer of hepatocytes arranged in radial
sinusoid: situated between the hepatic
plates, forming a complex network
central vein: occupies the centre of the
liver lobule
Liver lobule
Hepatic plates
Hepatic cords and liver sinusoids
Hepatocytes
polyhedral in shape, eosinophilic cytoplasm,
one or two large rounded nuclei with one or 2
typical nucleoli
EM: Mi, RER, SER, Golgi apparatus,
lysosomes, microbodies, inclusions
Mitochondria
provide the energy for the hepatocytes
Rough endoplasmic reticulum
synthesize some plasma proteins
Golgi apparatus
participate in the formation of bile and lipoprotein
Smooth endoplasmic reticulum
synthesize bile, triglyceride and LDL
metabolism of the lipid, hormones and
cholerythrin
inactivate steroid hormone
biotransformation of some materials
detoxification of noxious substances
Lysosomes
actively participate the metabolism of
hepatocyte and renewal of organelles
play a role in metabolism and transport of
cholerythrin
storage of iron
Microbodies
detoxification: catalase and peroxidase;
reduce the hydrogen peroxide into H2O
Inclusions
include glycogen, lipid droplets, pigment etc;
These contents vary according to physiologic state of human body
Bile canaliculi
between two adjacent hepatocytes
the membrane of hepatocyte projects to
the lumen, forming many microvilli
the cell membranes near the bile canaliculi
are firmly bound by junctional complexes
Bile canaliculi
Liver sinusoid spaces between the hepatic plates
irregular in shape
composed of only one discontinuous layer of
fenestrated endothelial cells, no diaphragm,
no basement membrane
Kupffer cells are located within the sinusoid
cavities
Kuffer cells in liver sinusoid
Liver sinusoid and space of D
isse
Space of Disse
separates the endothelium from the
hepatocytes
contains some reticular fibers and fat-storing
cells
Portal space:
the connective tissue separating the lobules
including
Interlobular arteries
Interlobular veins
Interlobular bile ducts
Portal spaces
Blood circulation:
portal V. interlobular V.
sinusoids
hepatic A. interlobular A.
central V.
sublobular V.
hepatic V.
( functional vessel)
(nutrient vessel)
Blood vessels of liver
(prepared Chinese ink injection through portal vein)
Discharge way of bile:
Bile canaliculi
Hering’s canals
Interlobular bile ducts
Hepatic duct
Common bile duct
Gallbladder
Cystic duct
duodenum
Gallbladder
mucosaSimple columnar Epi. , no Goblet cells
Laminar propria: C.T.
muscle layer: composed of an inner circular,
an outer longitudinal layers of smooth muscle
adventitia: most are fibrosa, some are serosa
Gallbladder