Histology of GIT II
PROF. DR. FAUZIAH OTHMAN
DEPT OF HUMAN ANATOMY
FPSK
Content
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Histology of the:
- spleen
- pancreas
- liver & extra hepatic biliary apparatus
spleen
Spleen
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spleen posses only efferent lymphatic vessels.
Spleen is surrounded by a capsule of dense connective
tissue from which emerge trabeculae, which divide the
parenchyma/splenic pulp, into incomplete compartment.
Splenic pulp
Has two compartment
1 white pulp( white spot; lymphoid nodules)
2.red pulp (dark red tissue, red blood cells)
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White pulp consist= periarterial lymphatic sheath and
the lymphoid nodules.
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Red pulp consist= splenic cords (Billroth’s cords) &
blood sinusoids.
Spleen
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Red Pulp: Clusters of Macrophages and Red Blood Cells.
White Pulp: Lymphocytes suspended on reticular Fibers
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The spleen is a fist-sized, spongy organ located behind the stomach
(removed in this illustration), just under the diaphragm. Part of the
lymphatic system, the spleen is composed of two types of tissue.
White pulp produces lymphocytes, which release antibodies into the
bloodstream to combat infection. More prominent is the red pulp, in
which macrophages filter broken cells, parasites, bile pigments, and
other useless substances from the blood. Iron from broken red
blood cells is stored in the spleen for later use. Despite this variety
of functions, an injured or diseased spleen can be removed in adults
without great consequence.
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Spleen, flattened, oblong organ that removes disease-producing
organisms and worn-out red blood cells from the bloodstream. The
spleen is situated in the upper left abdominal cavity, in contact with
the pancreas, the diaphragm, and the left kidney. It is supported by
bands of fibers that are attached to the peritoneum (the membrane
lining the abdominal cavity). The spleen varies in size but, in adult
humans, it is about 13 cm (about 5 in) long, up to 10 cm (4 in) wide
and 3.8 cm (1.5 in) thick, and weighs about 200 g (about 7 oz). The
spleen is fed by the splenic artery, and venous blood from the spleen
enters the liver.
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The spleen removes iron from the hemoglobin of red blood cells for
use in the body. It also removes such waste materials as bile
pigments for excretion as bile by the liver. The spleen produces
antibodies against various disease organisms and manufactures a
variety of blood cells. In some mammals (but not in humans) it
stores red blood cells and feeds them into the circulation to
maintain the volume of blood in cases of hemorrhage. In the unborn
child, the organ functions primarily to produce red blood cells, a
function that is normally taken over by the bone marrow after birth.
However, if diseases slow down this function in the bone marrow,
the spleen may again start to produce red blood cells.
Pancreas
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Both endocrine (pancreatic islets of Langerhans –
secretes insulin & glucagon) & exocrine gland (pancreatic
acini – secretes pancreatic juice)
Stomach
Tail
Body
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Under a microscope, stained sections of the pancreas
reveal two different types of parenchymal tissue.[2]
Lightly staining clusters of cells are called islets of
Langerhans, which produce hormones that underlie the
endocrine functions of the pancreas. Darker staining cells
form acini connected to ducts. Acinar cells belong to the
exocrine pancreas and secrete digestive enzymes into the
gut via a system of ducts.
Structure
Appearance
Function
Islets of Langerhans
Lightly staining, large,
spherical clusters
Hormone production
and secretion
(endocrine pancreas)
Pancreatic acini
Darker staining, small, Digestive enzyme
berry-like clusters
production and
secretion (exocrine
pancreas)
Pancreas
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Small cluster of glandular epithelial cells= Acini
A distinction between the two glands can be
made based on the absence of striated ducts
and the presence of the islets of Langerhans in
the pancreas.
Another characteristic detail is that in the
pancreas the initial portion of intercalated duct
penetrate the lumens of the acini.
Nuclei, surrounded by a pale cytoplasm,
belong to centoacinar cells that constitute the
intraacinar portion of the intercalated duct.
These cells are found ONLY in pancreatic acini
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Functions of Liver Storing glycogen (fuel for the body) which is made
from sugars.
Helping to process fats and proteins from digested food.
Making proteins that are essential for blood to clot (clotting factors)
Processing many medicines which you may take; helping to remove
poisons and toxins from the body
The liver also makes bile. This is a greenish-yellow fluid which contains bile
acids, bile pigments and waste products such as bilirubin. Liver cells pass
bile into bile ducts inside the liver. The bile flows down these ducts into
larger and larger ducts, eventually leading to the common bile duct. The
gallbladder is like a 'cul-de-sac' reservoir of bile which comes off the
common bile duct. After you eat, the gallbladder squeezes bile back into the
common bile duct and down into the duodenum (the first part of the gut
after the stomach). Bile in the gut helps to digest fats.
Liver & extra hepatic biliary apparatus
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Lobules comprised of rows of Hepatocytes arranged
radially around a central vein
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Hepatocytes surround blood sinusoids (capillary
structures) which are partially lined with phagocytic
Kupffer cells ( stellate reticuloendothelial).
Gallbladder
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The gallbladder is a sac located under the liver. It stores
and concentrates the bile produced in the liver
Gallbladder
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The wall of the gallbladder -mucosa that is
composed of a simple columnar epithelium of
absorptive cells and a lamina propria, a thin
irregular layer of smooth muscle cells (responsible
for the contraction and expulsion of the stored bile
in response to cholecystokinin), a well developed
perimuscular connective tissue layer, and the
serosa.
The mucosa is extensively folded when the
gallbladder is contracted and modestly folded
when it is relaxed. However, it does not contain villi
or tubular glands (crypts).
The underlying connective tissue is richly
vascularized.
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A tall columnar epithelium
modified for absorption.
The cells have an apical
brush border through
which water and ions are
absorbed.
Cholecystitis
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Inflammation of the gallbladder wall and nearby
abdominal lining.
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Cholecystitis is usually caused by a gallstone in
the cystic duct, the duct that connects the
gallbladder to the hepatic duct.
Symptoms of Cholecystitis
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intense and sudden pain in the
upper right part of the abdomen
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recurrent painful attacks for
several hours after meals
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pain (often worse with deep
breaths and extends to lower
part of right shoulder blade)
Nausea
Vomiting
rigid abdominal muscles on
right side
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slight fever
chills
jaundice - yellowing of the
skin and eyes.
itching (rare)
loose, light-colored bowel movements
abdominal bloating
How is cholecystitis diagnosed?
1.
2.
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Ultrasound (Also called sonography.)Endoscopic retrograde
cholangiopancreatography (ERCP)
Computed tomography scan (CT or CAT
scan) -