THE LIVE R

Assoc. Prof Dr. Karim Al-JashamyIMS/ MSU 2010

Hepatic Circulation

Hepatic Circulation

LIVER

Structure of the liver.The liver lobule in the

center is surrounded by the

portal space. Arteries, veins,

and bile ducts occupy the

portal spaces.

In the lobule, note the radial

disposition of the plates formed

by hepatocytes; the

sinusoidal capillaries separate the

plates. The bile canaliculi can be

seen between the hepatocytes.

The sublobular (intercalated)

veins drain blood from the

lobules.

Anatomy of a Lobule: A Portal Tract

Notice the

direction of

various flows.

Liver Lobule

Liver ParenchymaHepatocytes are

arranged in plates

one cell thick.

Blood flows over

plates through

sinusoids to reach

terminal hepatic

venule.

LOBULEHepatocytes Sinusoid

CV

Portal Tract

L = lymphatics

B = bile duct

A = arterioles

Portal Tract x10 Portal VeinBile ductuleHepatic Artery branch Lymphatic

Hepatocytes

Sinusoids

A Sinusoid

Bile Canaliculi

Bile Canaliculi

PANCREAS

Gland with Double Duties

• Endocrine and exocrine functions

• Exocrine anatomy

– CT capsule surrounds pancreas

– Septa divide it into sections

– Compound acinar gland

• Secretions

– 1500 – 3000 ml pancreatic fluid (alkaline)

– Contain water, ions, proteases, lipases, amylake,

nucleases, ribonuclease

The structure of pancreatic acini. Acinar cells are pyramidal, with

granules at their apex and rough endoplasmic reticulum at their

base. The duct partly penetrates the acini.

PANCREAS x10 SeptumDuct

Endocrine Gland

• Islet of Langerhans

– cells (glucagon) ~ 20%

– cells (insulin) ~ 70%

– cells (somatostatin) ~ 5%

Islet of LangerhansAcini

A section of the pancreas

showing an islet of

Langerhans surrounded

by pancreatic acinar cells.

The islet cells form cords

separated by blood

capillaries, here seen as

white spaces.

Islet is surrounded by

reticular fibers separating

it from acinar cells.

An islet of

Langerhans showing

{a} (A) cells

and {b} (B) cells.

Gomori’s trichrome

stain.

Electron-microscope

immunocytochemical localization

of insulin in a B cell of an islet of

Langerhans.

The black granules are gold

particles used to label anti-

insulin.

They indicate the sites where this

antibody was attached to the

insulin in the secretory granules.

Note also the clear zone between

the secretory material and the

granule membrane.

The main steps of

insulin synthesis

and secretion by a

B cell in the islets

of Langerhans.

RER, rough

endoplasmic

reticulum. (Based

on Orci L: A

portrait of the

pancreatic B cell.

Gallbladder

The gallbladder is a hollow,

pear-shaped organ attached to

the lower surface of the liver

It can store 30-50 mL of bile.

The wall of the gallbladder

consists of a mucosa composed

of simple columnar epithelium

and lamina propria, a layer of

smooth muscle, a perimuscular

connective tissue layer, and a

serous membrane