Pankreas & LienAnatomi & Fisiologi

dr. Rohmania Setiarini

Pancreas

Gland with both exocrine and endocrine functions

6-10 inch in length

60-100 gram in weight

Pancreas

Location: Retro-peritoneum, 2nd lumbar vertebral level

Extends in an oblique, transverse position

Parts of pancreas: head, neck, body and tail

Pancreas

Head of Pancreas

Includes uncinate process

Flattened structure, 2 – 3 cm thick

Attached to the 2nd and 3rd portions of duodenum on the right

Merges into neck on the left

Neck of Pancreas

2.5 cm in length

Superior border relates to the pylorus

Superior mesenteric vessels emerge from the inferior border

Pancreas

Body of Pancreas

Elongated, long structureSplenic vein runs embedded in the post. surface closer to the superior borderInferior surface is covered by transverse mesocolon

Tail of Pancreas

Narrow, short segment

Lies at the level of the 12th thoracic vertebra

Ends within the splenic hilum

Lies in the splenophrenic ligament

Anteriorly, related to splenic flexure of colon

Pancreatic Duct

Main duct (Wirsung) runs the entire length of pancreasJoins CBD at the ampulla of Vater2 – 4 mm in diameter, drains up to 20 secondary branchesDuctal pressure is 15 – 30 mm Hg (vs. 7 – 17 in CBD) thus preventing reflux and damage to panc. ductLesser duct (Santorini) drains superior portion of head and empties separately into 2nd portion of duodenum

Arterial Supply of Pancreas

Variety of major arterial sources (Celiac, SMA and Splenic)Celiac Common Hepatic Artery Gastroduodenal Artery Superior pancreaticoduodenal artery which divides into anterior and posterior branchesSMA Inferior pancreaticoduodenal artery which divides into anterior and posterior branches

Arterial Supply of Pancreas

Anterior and posterior collateral arcade supply headBody and tail supplied by splenic artery by about 10 branches

Three big branches from splenic are Dorsal pancreatic artery Pancreatica Magna (midportion of body) Caudal pancreatic artery (tail)

Venous Drainage of the Pancreas

Follows arterial supplyAnterior and posterior arcades drain head and the bodySplenic vein drains the body and tailUltimately, into portal vein

Lymphatic Drainage

Rich periacinar network that drain into 5 nodal groupsSuperior nodesAnterior nodes Inferior nodesPosterior PD nodesSplenic nodes

Innervation of PancreasSympathetic fibers from the splanchnic nerves

Parasympathetic fibers from the vagus

Parasympathetic fibers stimulate both exocrine and endocrine secretion

Sympathetic fibers have a predominantly inhibitory effect

Physiology – Exocrine Pancreas

500 to 800 ml pancreatic fluid secreted per day

Alkaline pH results from secreted bicarbonate which serves to neutralize gastric acid and regulate the pH of the intestine

Enzymes digest carbohydrates, proteins, and fats

Bicarbonate Secretion

Centroacinar cells and ductular epithelium secrete 20 mmol of bicarbonate per liter in the basal state

Fluid acts as a vehicle to carry inactive proteolytic enzymes to the duodenal lumen

Bicarbonate Secretion

Bicarbonate is formed from carbonic acid by the enzyme carbonic anhydrase

Major stimulantsSecretin, Cholecystokinin, Gastrin, Acetylcholine

Major inhibitorsAtropine, Somatostatin, Pancreatic polypeptide and

Glucagon

Enzyme Secretion

Acinar cells secrete isozymes amylases, lipases, and proteases

Major stimulants Cholecystokinin, Acetylcholine, Secretin

Synthesized in the endoplasmic reticulum of the acinar cells and are packaged in the zymogen granulesReleased from the acinar cells into the lumen of the acinus and then transported into the duodenal lumen, where the enzymes are activated.

Anatomy of Spleen

Spleen/lien

Weight: 75–250 grams.

Cranial to caudal axis: 15cm, thickness: 2–3cm.

The normal adult spleen contains 20–40ml of blood.

It receives about 5%of the cardiac output in the adult.

The white pulp includes periarteriolar lymphoid sheaths containing T lymphocytes and antigen-presenting cells, and lymphoid nodules with germina centres (secondary lymphoid follicles).

The red pulp comprises vascular sinusoids lined by fixed and free phagocytes and large numbers of interdigitating macrophages with long dendritic processes

Spleen Structure

The white pulp is circular in

structure and is made up mainly

of lymphocytes. It functions in a

manner similar to the nodules of the

lymph node.

The red pulp surrounds the white

pulp and contains mainly red blood

cells and macrophages. The main

function of the red pulp is to

phagocytize old red blood cells.

Function

The spleen is a sophisticated filter that monitors and manages blood cells and immune functionsDuring fetal development the spleen produces red and white blood cellsRed cells that pass through the spleen undergo a “cleaning” or repairAbnormal and old cells are destroyed

Function

RBC’s coated with IgG and IgM are removed and destroyed The spleen is the site of destruction in

autoimmune disease states (hemolytic anemia) Parasites such as malaria can be removed as well

The spleen is involved in specific and nonspecific immune responses (promotes phagocytosis and destruction of bacteria)