Accessory Organs
Accessory Organs
Accessory Organs
Pancreas
Pancreas
Gland with both exocrine and endocrine
functions
6-10 inch in length
60-100 gram in weight
Location: retro-peritoneum*, 2nd lumbar
vertebral level
Extends in an oblique, transverse position
Parts of pancreas: head, neck, body and tail
Accessory Organs
The pancreas
A glandular organ located behind stomach
Produces pancreatic juices containing enzymes to
digest food
Juices enter duodenum through pancreatic duct
Enzymes in juices break down sugars, proteins, and fats
Produces insulin, secreted into bloodstream
Regulates metabolism (or burning) of carbohydrates
to convert glucose (blood sugar) into energy
Alkaline fluid introduced with enzymes neutralizes acidic
chyme
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
Neck of Pancreas
2.5 cm in length
Antero-superior surface supports the
pylorus
Superior mesenteric vessels emerge from
the inferior border
Pancreas
Body of Pancreas
Elongated, long structure
Anterior surface, separated from stomach
by lesser sac
Tail of Pancreas
Pancreatic Duct
Main duct (Wirsung) runs the entire length
of pancreas
Joins CBD at the ampulla of Vater
Pancreas
Exocrine Pancreas
2 major components acinar cells and ducts
Constitute 80% to 90% of the pancreatic
mass
Acinar cells secrete the digestive /
pancreatoc enzymes
Exocrine Pancreas
Ductular system - network of conduits that
carry the exocrine secretions into the
duodenum
Exocrine Pancreas
Pancreatic enzymes -> amylase, lipase, and
trypsinogen)
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
Lipase
function optimally at a pH of 7 to 9
emulsify and hydrolyze fat in the presence of bile
salts
Enzymes of Pancreas
Proteases
essential for protein digestion
secreted as proenzymes and require activation for
proteolytic activity
duodenal enzyme, enterokinase, converts
trypsinogen to trypsin
Trypsin, in turn, activates chymotrypsin, elastase,
carboxypeptidase, and phospholipase
Endocrine Pancreas
Accounts for only 2% of the pancreatic
mass
Nests of cells - islets of Langerhans
Four major cell types
Alpha (A) cells secrete glucagon
Beta (B) cells secrete insulin
Delta (D) cells secrete somatostatin
F cells secrete pancreatic polypeptide
Insulin
Synthesized in the B cells of the islets of
Langerhans
Major stimulants
Glucose, amino acids, glucagon, sulfonylurea
compounds, -Sympathetic fibers
Glucagon
Secreted by the A cells of the islet
Glucagon elevates blood glucose levels through
the stimulation of glycogenolysis and
gluconeogenesis
Somatostatin
Secreted by the D cells of the islet
Inhibits the release of growth hormone
Inhibits the release of almost all peptide
hormones
Inhibits gastric, pancreatic, and biliary
secretion
Used to treat both endocrine and exocrine
disorders
LIVER
ANATOMY OF LIVER
Liver is a large, solid, wedge shaped organ
found in the RUQ
It is the largest organ of the body and
contributes about 2% of the total body weight.
Weighs 1600gm in male and 1300gm in female
Liver
4 lobes, located under
the diaphragm
Connected to the gall
bladder via the
common hepatic duct
Hepatic artery
400-500 ml/min blood flow
Oxygenated blood
Blood supply
80% of blood supply is derived from portal
vein.
20% is derived from hepatic artery.
Before entering the liver both hepatic artery
and portal vein divide into right and left
branches.
Histology of liver
Liver physiology
Liver performs many different functions
which can be summarized as:
1. Synthesis of bile salts
These are the salts of bile acids.
Primary bile acids are cholic and
chenodeoxycholic acid.
2. Synthesis of proteins:
Albumin
Blood coagulation factors I,II,V,VII,IX,X and
also fibrinolytic agents.
Transport proteins like Ceruloplasmin and
Transferrin.
Angiotensinogen
3. Fat metabolism
Oxidation of fatty acids to supply energy for
other body functions.
Synthesis of large quantities of cholesterol,
phospholipids and most lipoproteins.
Synthesis of fat from proteins and
carbohydrates
4. Carbohydrate metabolism
Storage of large amounts of glycogen.
Conversion of galactose and fructose to
glucose.
Gluconeogenesis
5. Vitamin metabolism
6. Formation of urea (Ammonia -> urea)
7. Responsible for inactivation of many drugs
8. Detoxification of many toxic substances.
9. Metabolism of ethanol.
10. De-activation of various hormones.
11. Excretion of bile pigments, cholesterol and
some metals.
12. Stores iron as ferritin and also vitamins A,
D and B12.
GALLBLADDER
The gallbladder
Small, muscular sac located under liver and
attached to it by connective tissue
Stores and concentrates bile, received from
liver
When bile is needed to emulsify fats in
digestive tract, the gallbladder contracts and
pushes bile through common bile duct into
duodenum
Gallbladder
Stores and concentrates bile
Expels bile into duodenum
Bile emulsifies fats
Gallbladder
Figure 24.22
Figure 24.1
Processes of
the Digestive
System
Figure 14.11
END