Sheet: liver and pancreas

Done by: nisreen obeidat

Embryology of the liver

The liver develops in the ventral mesentery of the foregut and divides the ventral mesentery

into:

1)lesser omentum (between the liver and the stomach)

2)Falciform ligament (between the liver and the anterior abdominal wall) that has the

umbilical vein

Fetal circulation:

2 Umbilical arteries (from the fetal aorta) that have deoxygenated blood goes to the

placenta then it turns back to the fetal by the left umbilical vein and the returning blood is

oxygenated and goes to the fetal liver (won't supply it just passing) then continues its way to

the ductus venosus then to the IVC then to the right atrium then the left atrium through

foramen oval then to the left ventricle then the aorta and what goes to the right ventricle

will be pumped to the pulmonary trunk then to the lungs & aorta through ductus arteriosus

Remember: right umbilical vein degenerates in the 5th week

After birth:

1)Ductus arteriosus becomes ligamentum arteriosum

2)Thrombosis of the umbilical vein so it becomes fibrous tissue that is called "umbilical

ligament or ligamentum teres"

Anatomy of the liver

**Has a wedge shape and directed downwards & backwards & left

**Largest organ in the body, weights 1.5 Kg, located in the right hypochondrial region

**The IVC is imbedded in the liver

Has 2 surfaces: visceral (faces the viscera) & diaphragmatic (faces the diaphragm)**

**The liver is fixed by ligaments that are attached to the anterior abdominal wall &

diaphragm

**It is divided into 2 main lobes left & right by intralobar fissure

Left lobe: small lobe

Right lobe: the big lobe; subdivided into smaller lobes which are :

Caudate lobe: surrounded by IVC &ligamentum venosus &porta hepatis, and it's connected

to right lobe by caudate process

Quadrate lobe: surrounded by falciform ligament & porta hepatis & gallbladder

"Whole peritoneal covering except one area posteriorly called "BARE AREA**

Which is related to the Right suprarenal gland & IVC

**Falciform ligament extends superiorly and divides the hypophrenic area into 2 recesses

(left & right) and interiorly it's attached with the anterior abdominal wall

**There is reflection of the peritoneal to the diaphragm and the result is

Right side: upper & lower coronary ligaments meet together and form the right triangular

ligament

Left side: left triangular ligament

RELATION:

Convex Diaphragmatic surface: interiorly >> diaphragm & posteriorly there is bare area and

I'd mentioned its relation

Flat Visceral surface :

1)Stomach & duodenum

2)Esophagus

3)Lesser omentum

4)Gallbladder

5)Right colic flexure

6)Right kidney & right suprarenal gland

gallbladder: its sac composed of (fundus &body & neck) its importance is:

1.Collects bile 2.concentrating bile by water absorption 3.secreting mucous

*fundus: bulging below the lower margin of liver

*body: fixed to the visceral surface of the liver by the peritoneum so the venous drainage

between them is continuous

*from neck the cystic duct originates and there is a spiral valve to prevent the bending of the

neck and closure of it

Left hepatic duct + right hepatic duct = common hepatic duct

Common hepatic duct + cystic duct= common bile duct

Common bile duct + major pancreatic duct = ampulle of vater opens in the midpoint of 2nd

part of the duodenum through major papilla

Remember: the free margin of the lesser omentum has 3 tubes: common bile duct >>

hepatic artery>>portal vein from out to in

The length of common bile duct: 3 inches (7.5 cm)**

Inch above the duodenum & inch behind the first part of duodenum (portal vein

&gastrodoudenal artery) &inch behind the head of pancreas

Blood supply** :

Hepatic arteries (right & left) = 25% of blood supply (oxygenated blood)

Portal circulation =75% of blood supply (deoxygenated blood)

Venous drainage: hepatic veins (2-4) then IVC**

**Nerve supply: from celiac plexus sympathetic (greatest splanchnic nerves) &

parasympathetic (hepatic branches of the vagus nerve)

Remember: cranial parasympathetic nerves are 3, 7,9,10

Lymphatic drainage** :

Diaphragmatic surface >> anterior mediastinal lymph nodes

Visceral surface >> porta hepatis lymph nodes

Inside the liver >> posterior mediastinal lymph nodes OR porta hepatis

Histology of the liver

The liver is divided into thousands of small units called lobules by thin layer of connective

tissue .

Each lobule is about 1mm in diameter and roughly hexagonal in shape .

The Lobule is composed of radiating double plates of liver cells (Hepatocytes) separated by a

vascular sinusoidal network .

Each lobule has a central vein in the middle and portal triads at the vertices

Each portal triad contains branch of hepatic artery, portal vein and Bile duct.

Sinusoids have an incomplete lining of highly fenestrated endothelial cells, some of these

cells are macrophagic in function (reticulo-endothelial cells), and they are called Kupffer

cells.

The space between endothelium and hepatocytes is called the Space of Disse. In these

spaces, lymph is collected and delivered to lymphatic capillaries. Lymph is collecting in

hepatic duct outside the liver .

Blood from the branches of hepatic artery and portal vein in the Portal triad, drains into

sinusoids and then to the central vein. Central Veins carry the blood to hepatic veins which

end in the Inferior vena cava.

Bile is formed by liver cells and is discharged into the bile canaliculi within layers of the cell

plates, and then drains into bile duct of the triads.

www.google.co.uk/search?Histology of Liver

Anatomy & histology of pancreas

Pancreas is a soft lobulated organ located retroperitoneally across the posterior abdominal

wall, it sits behind the stomach across the back of the abdomen.

It is described as an organ having head, neck, body, and tail.

The head is disc-shaped and lies within the concavity of the duodenum .

Part of the head extends to the left behind the superior mesenteric vessels, it is called

Uncinate process.

The body extends to the left side and ends as a tail near the hilus of the spleen.

The pancreas is made up of two types of glands ,

1-An exocrine gland that secretes digestive enzymes and Sodium bicarbonate into the

duodenum through the main and accessory pancreatic ducts. Both ducts are usually

interconnected.

2- An endocrine gland, which consists of the islets of Langerhans, secretes hormones into

the bloodstream .

Islets of Langerhans are named for the German physician Paul Langerhans, who first

described them in 1869. The normal human pancreas contains about 1,000,000 islets .

Cells of islets of Langerhans

1-Beta cells (?-cells), they make about 65-80% of the cells in the islets and produce Insulin.

2-alpha cells (?-cells), 15-20%, they produce an opposing hormone, Glucagon which releases

glucose from the liver and fatty acids from fat tissue.

3-Delta cells (?-cells), 3-10%, they secrete somatostatin a strong inhibitor of somatotropin,

insulin, and glucagon; its role in metabolic regulation is not yet clear. Somatostatin is also

produced by the hypothalamus and functions to inhibit secretion of growth hormone by the

pituitary gland.

**Anterior relation : anterior abdominal wall & transverse colon & mesentery of transverse

colon & lesser sac & stomach

Posterior relation **

Head >> IVC & Neck : portal vein & Body >>splenich vein & splenich artery & lt kidney & lt

suprarenal gland & posterior abdominal wall & Tail : hilum of the spleen

**Lienorenal ligament : connects between kidney & spleen

**Uncinate process: directed to the left; anterior to it there is superior mesenteric artery &

superior mesenteric vein

www.google.co.uk/search?PPancreas

AcinIi

Pancreas

Histology of gall bladder

The gall bladder is a simple muscular sac, lined by a simple columnar epithelium. The inner

surface of the gall bladder is covered by the mucosa. The sufrace is made up of a simple

columnar epithelium. The epithelial cells have microvilli, and look like absorptive cells in the

intestine. Underneath the epithelium is the lamina propria. The wall of the bladder does

not have a muscularis mucosae and submucosa.

The muscularis externa (muscle layer) contains bundles of smooth muscle cells, collagen and

elastic fibres. Underneath this, on the outside of the gall bladder is a thick layer of

connective tissue, which contains large blood vessels, nerves and a lymphatic network.

Where this layer is attached to the liver, it is called the adventia. In the unattached region,

there is an outer layer of mesothelium and loose connective tissue (the serosa).

Gall bladder