Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Digestive System III Lecture PPT
DIGESTIVE SYSTEM III
HISTOLOGY OF LIVER, GALL BLADDER
AND PANCREAS
HISTOLOGY OF LIVER
INTRODUCTION
? Liver is the largest internal organ.
? In adults weight-- 1.5 kg (2% of the body weight).
? Location--Right upper quadrant of the abdomen.
? Dual blood supply--Portal vein and hepatic artery.
? Liver is surrounded by thin connective tissue
capsule called Glisson's capsule.
? Glisson's capsule thickened at the porta hepatis and
sends trabeculae into the interior dividing
parenchyma into lobules.
? These trabeculae carry branches of hepatic artery,
portal vein, and bile duct.
? Liver lobules:
? Hexagonal areas that form the structural &
functional unit of liver.
? Scanty connective tissue between lobules.
? Each lobule is made up of cords of liver cells
(hepatocytes) separated by sinusoids.
? At the periphery of each lobule there are several
portal triad.
? Central vein in the centre of each lobule and drain
blood from lobules into hepatic vein.
? Bile canaliculi: spaces present between plasma
membrane of adjacent liver cells.
Different types of liver lobules
A.Classical liver
lobule
B. Portal liver
lobule
C. Liver acinus
? Hepatocytes (liver cells)
? Shape--polygonal
? Nucleus--Large, round ¢ral (may binucleated).
? Consitute about 80% of liver volume.
? Life span about 5 months.
? Capable of regeneration.
? Forms hepatic cords (may branch & anastomose).
? Liver cells has 5-12 sides, some sides exposed to
sinusoids and other sides shows infolding between
adjacent cells to form bile canaliculi.
? Hepatic sinusoid--
? Vascular channels between the plates of
hepatocytes.
? Lined by endothelial and phagocytic (kupffer) cells.
? The venous and arterial blood mixes in hepatic
sinusoids
? Space of Disse (perisinusoidal space)--
Between sinusoidal endotheilum and hepatocytes.
? Ito cells (hepatic stellate cells)--
Found in perisinusoidal spaces.
Involeved in storage of vitamin A and lipid
? Bile canaliculi
? Smallest branches of the biliary tree.
? They empty into bile canals of Hering composed of
cuboidal epithelium (cholangiocytes).
? Bile canal merge to form bile ductules
? Bile ductules merge, enlarge, and form right and
left hepatic ducts leaving the liver.
? Into the canaliculi hepatocytes continuously secrete
bile.
GALL BLADDER
? Gall bladder is temporary storehouse of bile
and concentrate it by water re-absorption.
? Layers of gall bladder--
a) Mucosa
b) Fibromuscular layer
c) Serosa/adventitia
? Mucosa--
? Lining epithelium simple columnar epithelium.
? These cells have many small microvilli on their
apical surface.
? These cells involved in absorption of water from
stored bile.
? Lamina propria is present.
? Mucosal gland, muscularis mucosae and
submucosa are absent.
? Fibromuscular layer--
? Composed of randomly arranged smooth
muscles.
? In between muscles fibre is dense connective
tissue that is rich in elastic fibres.
? Serosa--
? Inferior surface is covered by serosa and rest is
by adventitia.
PANCREAS
? Mixed gland i.e.
consists of an
exocrine &
endocrine portion.
? Exocrine part:
secretes pancreatic
juice.
? Endocrine part:
secretes hormones.
Histology of Exocrine Pancreas
? Covered with a capsule.
? Septas arise from capsule which divide the
gland into many small lobules.
? Interlobular connective tissue contains large
ducts, blood vessels & nerve fibres.
? Interlobular connective tissue surrounds the
acini, small ducts & islets of Langerhans.
? Pancreatic Acini--
? Serous in nature.
? Lined by pyramidal cells and have small lumen.
? Acinar cells--
supranuclear region is filled with zymogen granules.
Infranuclear region is intensely basophilic.
? Extensive duct system--
intralobular (intercalated), interlobular & main duct.
? Acinar lumen may show pale staining cells of
intercalated duct (centroacinar cells).
Histology of Endocrine Pancreas
? In the form of "islands": Islets of Langerhans
? Scattered among the acini of exocrine part.
? Cells of islets are arranged as anastomosing
plates.
? Islets contain 4 types of cells:
? A(alpha) cells--20% , secrete glucagon
? B (beta) cells--70% , secrete insulin
? D (delta) cells--5% , secrete somatostatin
? F or PP cells-- secrete pancreatic polpetides
Self Assessement
1] Which of the following cell is responsible for
myelination of axon in CNS ?
a) Astroccytes
b) Oligodendrocytes
c) Microglia
d) Schwan cells
2.] Thymus-dependent zone of a lymph node is
(a) Cortex
(b) Paracortex
(c) Medullary cords
(d) Medullary sinuses.
3.] White pulp of spleen can be identified
differentially from the lymphatic nodule of lymph
node by the presence of
(a) Germinal centre
(b) Corona
(c) Central arteriole
(d) Lymphocytes
4.]Hassall's corpuscles are present in
(a) Lymph node
(b) Spleen
(c) Thymus
(d) Tonsil
5.]Crypts of palatine tonsil are lined by
(a) Simple squamous epithelium
(b) Stratified squamous nonkeratinized epithelium
(c) Pseudostratified columnar epithelium
(d) Stratified squamous keratinized epithelium
6.] All of the following layers are present in
epidermis of THIN SKIN except ?
a) Stratum basale
b) Stratum spinosum
c) Stratum lucidum
d) Stratum corneum
7.] Thin skin is characterised by the presence of
(a) Thin epidermis
(b) Hair follicle
(c) Sebaceous gland
(d) All of the above
8.] Lining epithelium of trachea ?
a) Simple sqamous
b) Simple columnar
c) Pseudostratified ciliated columnar
d) Stratified squamous non-keratinized
9.] Blood-air barrier is formed by all except ?
a)Endothelium of capillary
b)Lining epithelium of alveolus
c)Fused basal lamina of endothelium and
epithelium
d) only endothelium of capillary
10.] Elastic cartilage is present in which part of
respiratory tract?
a) Trachea
b) Bronchus
c) Epiglottis
d) None
? 1.Ans: b) Oligodendrocytes
? 2.Ans (b) Paracortex
? 3.Ans (c) Central arteriole
? 4 Ans (c) Thymus
? 5 Ans (b) Stratified squamous
nonkeratinized epithelium
? 6. Ans(c) Stratum lucidum
? 7.Ans(d) All of the above
? 8.Ans (c) Pseudostratified ciliated columnar
? 9.Ans (d) Only endothelium of capillary
? 10.Ans(c) Epiglottis
This post was last modified on 30 November 2021