The liver and pancreas are accessory digestive glands that secrete substances important for digestion. The liver produces bile which aids in fat digestion. It also filters and metabolizes nutrients, stores vitamins and iron, and produces coagulation factors. The pancreas secretes enzymes like trypsin and lipase, as well as bicarbonate, into the small intestine to help break down proteins, carbohydrates, and fats. The gallbladder stores and concentrates bile produced by the liver and releases it in response to food in the duodenum to aid fat digestion.

1. ACCESSORY GLANDS OF
THE DIGESTIVE SYSTEM

2. Diaphragmatic aspect Visceral aspect

3. The LIVER
 Filtration & storage of blood
 Metabolism of CHO, proteins, fats, hormones,
etc.
 Formation of bile
 Storage of vitamins & iron

4. Liver lobule
 Basic functional & anatomical unit of the liver.
Central vein
Hepatocytes
Bile canaliculi
Hepatic sinusoids

7. HEPATOCYTES
CENTRAL VEIN

8. PLATES OF HEPATOCYTES
BILE CANALICULI

9. BILE DUCT
PORTAL VENULE

10. HEPATIC SINUSOIDS
PORTAL VENULE

11. PORTAL ARTERIOLE

12. ENDOTHELIAL CELLS
KUPFFER CELLS

13. SPACES OF DISSE
LYMPHATIC DUCT

14. PORTAL TRIAD

15. High blood flow
 About 1350 ml/min of blood flows from the portal
vein and hepatic artery into the liver sinusoids*
 The pressure difference (9 mmHg) between the
portal vein and hepatic vein shows that resistance
to blood flow through the sinusoids is normally very
low**

16. Cirrhosis
 Occurs when the liver parenchymal cells are
destroyed and replaced with fibrous tissue,
thereby impeding blood flow through the liver*

17. Blood reservoir
 The liver is a large, expandable organ capable of
acting as valuable blood reservoir (in times of
excess blood volume) and capable of supplying
extra blood (in times of diminished blood
volume).

18. Metabolic Functions of
the Liver

19. Carbohydrate metabolism
1. Storage of large amounts of glycogen
2. Conversion of galactose & fructose to glucose
3. Gluconeogenesis
4. Formation of chemical compounds from
intermediate products of CHO metabolism

20. Fat metabolism
1. Oxidation of fatty acids to supply energy for
body functions
2. Synthesis of cholesterol, phospholipids, & most
lipoproteins
3. Synthesis of fat from protein & CHO

21. Protein metabolism
1. Deamination of amino acids
2. Formation of urea from removal of ammonia
from body fluids
3. Formation of plasma proteins
4. Interconversions of amino acids

22. Storage site for vitamins
 The liver stores vitamin A, vitamin D & B12.
 Vit. A – can be stored for 10 months
 Vit. D – can be stored for 3-4 months
 Vitamin B12 – can be stored to last for 1 year or
several years

23. Storage of iron as ferritin
 The greatest proportion of iron in the body* is
stored in the liver as ferritin.
 Hepatic cells contain large amounts of
apoferritin**
 The apoferritin-ferritin system act as a blood
iron buffer*** and as an iron storage medium.

24. Formation of coagulation factors
 Substances formed in the liver that are used in
coagulation process include:
Fibrinogen
Thrombin
Accelerator globulin
Factor VII

25. Detoxification of harmful substances
 The liver removes or excretes drugs*, hormones,
other substances.
 Hormones that are altered or excreted by the
liver: thyroxine and all steroid hormones**
 One of the major routes for calcium excretion
(bile)

26. Secretion of the bile
 BILE
 A thick, bitter, golden-brown or greenish-yellow
alkaline (pH 7.6-8.6) fluid
 Secrete normally 1 liter/day (human)

27. Secretion of the bile
 2 major functions (bile)
1. Important in fat digestion & absorption (bile
acids)*
 Emulsification
2. Serves as a means for excretion of important
waste products (e.g., bilirubin, excess
cholesterol)**

28. Physiologic anatomy of biliary secretion
Hepatocytes
Bile
canaliculi
Bile ducts
Bile acids, cholesterol,
organic constituents

29. BILE DUCT
Sodium & bicarbonate ions (watery solution)
Secretin

30. Physiologic anatomy of biliary secretion
Hepatic
duct
Common
bile duct
Cystic duct
May empty into the
duodenum

31. Schema of the gallbladder and hepatic ducts,
visceral aspect.
Hepatic
ducts

32. BILE DUCT
BILE DUCT
•The main excretory channel for
bile to the duodenum formed by
the union of the common bile
duct and cystic duct.
•It opens to the major duodenal
papillae together with the
pancreatic duct.
Major duodenal
papilla

33. GALLBLADDER
 The sac storing and concentrating bile.
 Composition of bile: water, bile salts,
bilirubin, cholesterol fatty acids, lecithin,
Na+, K+, Ca++, Cl-, HCO3-

35. GALLBLADDER
 Maximum volume it can hold is 30-60 mL.
 As much as 12 hours (450 mL) of bile
secretion can be stored
H2O, Na+, Cl- are continually absorbed
through its mucosa – concentrating bile
constituents: bile salts, cholesterol, lecithin,
bilirubin*

36. Composition of bile
Liver Bile Gallbaldder Bile
Water 97.5 g/dL 92 g/dL
Bile salts 1.1 g/dL 6 g/dL
Bilirubin 0.04 g/dL 0.3 g/dL
Cholesterol 0.1 g/dL 0.3 to 0.9 g/dL
Fatty acids 0.12 g/dL 0.3 to 1.2 g/dL
Lecithin 0.04 g/dL 0.3 g/dL
Na+ 145.04 mEq/L 130 mEq/L
K+ 5 mEq/L 12 mEq/L
Ca++ 5 mEq/L 23 mEq/L
Cl- 100 mEq/L 25 mEq/L
HCO3- 28 mEq/L 10 mEq/L

37. Emptying the gallbladder
 The gallbladder begins to empty when food (esp. fatty)
is digested in the upper GIT*
 Mechanism: rhythmical contractions of the gallbladder
wall & simultaneous relaxation of the sphincter of
Oddi**
 Cholecystokinin – most potent stimulus for causing
gallbladder contractions***
 Presence of fatty foods in the duodenum – stimulus for CCK entry
into the blood.

38. Function of Bile Salts
1. Emulsifying or detergent function
 Allows the fat globules to be broken down
into minute sizes.
2. Aids in absorption of lipids in the intestine
 Micelles – complex that aids in the
absorption of fats.

39. Gallstones
 Calculus (cholesterol) formed in the gallbladder
or biliary passages*
 The amount of cholesterol in the bile is partly
determined by the quantity of fat that the person
eats.
 Individuals on a high fat diet (years) are more
prone.

40. PANCREAS
 An encapsulated, lobulated, compound
tubuloacinar gland containing both exocrine
and endocrine parts.

42. PANCREAS
 Exocrine pancreas – secretes the
pancreatic juice conveyed to the duodenum
by the pancreatic ducts.
 Endocrine pancreas (pancreatic Islets or
Islets of Langerhans) – secretes glucagon
(alpha cells) and insulin (beta cells).

43. ACINAR CELLS
 secrete enzyme-rich pancreatic
juice

45. Pancreatic digestive enzymes
 Contains (1) enzymes – digestion of all 3
major food types (proteins, carbohydrates,
fats; (2) bicarbonate ions – neutralize the
acidity of chyme.

46. Pancreatic enzymes for protein
1. Trypsin
2. Chymotrypsin
3. Carboxypeptidase

47. Pancreatic digestive enzymes
 Pancreatic amylase – hydrolyzes starches,
glycogen, most CHO (except cellulose) to form
disaccharides & trisaccharides.
 Fat digestion: (a) pancreatic lipase, (b)
cholesterol esterase, (c) phospholipase*

49. Secretion of trypsin inhibitor

50. Common bile duct
Hepatic ducts
Common hepatic ducts
Pancreatic ducts
Minor duodenal papilla
Major duodenal papilla
1