The accessory organs of the digestive system include the salivary glands, liver, gallbladder and pancreas. The liver performs many vital functions including metabolic regulation, hematological regulation and bile production. It regulates nutrient levels, filters toxins, stores vitamins and produces plasma proteins and bile. The liver lobule is the basic functional unit, with hepatocytes arranged in plates around a central vein and sinusoids. Blood enters through the hepatic artery and portal vein and leaves through hepatic veins.

1. Accessory Glandular
Digestive Organs

2. • The accessory glandular organs of the digestive tract are the salivary glands, the
liver, the gallbladder, and the pancreas.
• The glandular organs produce and store enzymes and buffers that are essential to
normal digestive function.
• In addition to their roles in digestion, the salivary glands, liver, and pancreas have
exocrine functions.
• The liver and pancreas have other vital functions in addition to their roles in the
digestive process.

3. The Liver
• The liver is the largest visceral organ, and it is one of the most versatile organs in
the body . Most of its mass lies within the right hypochondriac and epigastric
regions.
• It weighs about 1600 g in males and about 1300 g in females.
• This large, firm, reddish-brown organ provides essential metabolic and synthetic
services that fall into three basic categories: metabolic regulation, hematological
regulation, and bile production.

4. ● Metabolic regulation: The liver represents the central clearinghouse for
metabolic regulation in the body.
• Circulating levels of carbohydrates, lipids, and amino acids are regulated by the
liver.
• All blood leaving the absorptive surfaces of the digestive tract enters the hepatic
portal system and flows into the liver.
• This arrangement gives liver cells the opportunity to extract absorbed nutrients
or toxins from the blood before they reach the systemic circulation through the
hepatic veins. Liver cells, or hepatocytes, monitor the circulating levels of
metabolites and adjust them as necessary.
• Excess nutrients are removed and stored, and deficiencies are corrected by
mobilizing stored reserves or performing appropriate synthetic activities.
• Circulating toxins and metabolic waste products are also removed for subsequent
inactivation, storage, or excretion.
• Finally, fat-soluble vitamins (A, D, K, and E) are absorbed and stored in the liver.

5. • ● Hematological regulation: The liver is the largest blood reservoir in the body,
and it receives about 25 percent of the cardiac output.
• As blood passes through the liver sinusoids, phagocytic cells in the liver remove
old or damaged RBCs, cellular debris, and pathogens from the circulation, and
liver cells synthesize plasma proteins that contribute to the osmotic
concentration of the blood, transport nutrients, and establish the clotting and
complement systems.
• ● Synthesis and secretion of bile: Bile is synthesized by liver cells, stored in the
gallbladder, and excreted into the lumen of the duodenum.
• Bile consists mostly of water, with minor amounts of ions, bilirubin (a pigment
derived from hemoglobin), and an assortment of lipids collectively known as the
bile salts.
• The water and ions assist in the dilution and buffering of acids in chyme as it
enters the small intestine.
• Bile salts associate with lipids in the chyme and make it possible for enzymes to
break down those lipids into fatty acids suitable for absorption

11. SURFACES OF THE LIVER
• The liver is usually described as having superior, anterior, right, posterior and
inferior surfaces, and has a distinct inferior border .
• At the infrasternal angle, the inferior border is adjacent to the anterior abdominal
wall and accessible to examination by percussion, but not usually palpable,
except on deep inspiration.
• In the midline, the inferior border of the liver is near the transpyloric plane
• The inferior border is sharp anteriorly where it separates the anterior surface
from the inferior surface. It is somewhat rounded laterally where it separates the
right surface from the inferior surface. The sharp anterior part is marked by:
• a. An interlobar notch or the notch for the ligamentum teres.
• b. A cystic notch for the fundus of the gallbladder
• In the epigastrium, the inferior border extends from the left 8th costal cartilage to
the right 9th costal cartilage.

13. • The liver is divided into right and left lobes by the attachment of the falciform
lignment anteriorly and superiorly; by the fissure for the ligamentum teres
inferiorly; and by the fissure for the ligamentum venosum posteriorly.
• The right lobe is much larger than the left lobe, and forms five sixth of the liver. It
contributes to all the five surfaces of the liver, and Presents the caudate and
quadrate lobes
• The caudate lobe is situated on the posterior surface' It is bounded on the right
by the groove for the inferior vena cava, on the left by the fissure for the
ligamentum venosum, and inferiorly by the portahepatis. Above it is continuous
with the superior surface. Below and to the right, just behind the porta hepatis, it
is connected to the right lobe of the liver by the caudate process . Below and to
the left it presents a small rounded elevation called the papillary process.
• The quadrate lobe is situated on the inferior surface, and is rectangular in shape.
It is bounded anteriorly by the inferior border,posteriorly by porta hepatica,on
the right by the fossa of gallbladder and on left by fissure for the ligamentum
teres

14. • Porta hepatica is a deep transverse fissure about 5 cm long ,situated on the
inferior surface of the right lobe of liver.it lies between caudate lobe above and
quadrate lobe below and in front. The portal vain ,the hepatic artery and hepatic
plexus of nerves enter the liver through porta hepatica, while the right and left
hepatic ducts and few lymphatics leave it.
• The lef lobe is smaller than right and forms only one sixth of the liver
• A triangular bare area on the posterior surface of the right lobe, limited by the
superior and inferior layers of the coronary ligament and by the right triangular
ligament.
• 2 The groooe for the inferior vena cava, on the posterior surface of the right lobe
of the liver, between the caudate lobe and the bare area.
• 3 The fossa for the gallbladder which lies on the inferior surface of the right lobe
to the right of the quadrate Iobe.

16. SEGMENTS
• On the basis of the intrahepatic distribution of the hepatic artery, the portal vein and
the biliary ducts, the liver can be divided into the right and left functional lobes.
• These do not correspond to the anatomical lobes of the liver.
• The physiological lobes are separated by a plane passing on the anterosuperior surface
along a line joining the cystic notch to the groove for the inferior vena cava.
• On the inferior surface the plane passes through the fossa for the gallbladder; and on
the posterior surface it passes through the middle of the caudate lobe . The right lobe is
subdivided into anterior and posterior segments, and the left lobe into medial and
lateral segments.
• Thus there are four segments in the liver.
• a. Right anterior (V and VIII),
• b. Right posterior (VI and VII),
• c. Left lateral (II and III)
• d. Left medial (I and IV).
• The hepatic segments are of surgical importance.
• The hepatic veins tend to be intersegmental in their course.

19. • The blood Supply to the Liver
• Two blood vessels deliver blood to the liver, the hepatic artery proper and the
hepatic portal vein .
• Roughly one-third of the normal hepatic blood flow arrives via the hepatic artery,
and the rest is provided by the hepatic portal vein. Blood returns to the systemic
circuit through the hepatic veins that empty into the inferior vena cava.
• The arterial supply provides oxygen-rich blood to the liver, and the hepatic portal
vein supplies nutrients and other chemicals absorbed from the intestine.

23. Histological Organization of the Liver
• Each lobe of the liver is divided by connective tissue into approximately 100,000 liver lobules, the basic functional
units of the liver.
• The Liver Lobule The liver cells, or hepatocytes (HEP-a-tō-sīts), in a liver lobule form a series of irregular plates
arranged like the spokes of a wheel
• The plates are no more than two cells thick up to the age of seven, and then are only one cell thick after that age.
• The exposed hepatocyte surfaces are covered with short microvilli.
• Sinusoids between adjacent plates empty into the central vein. The fenestrated walls of the sinusoids contain
large openings that allow substances to pass out of the circulation and into the spaces surrounding the
hepatocytes.
• In addition to typical endothelial cells, the sinusoidal lining includes a large number of Kupffer (KOOP-fer) cells,
also known as stellate reticuloendothelial cells.
• These phagocytic cells are part of the monocyte-macrophage system, and they engulf pathogens, cell debris, and
damaged blood cells.
• Kupffer cells also engulf and retain any heavy metals, such as tin or mercury, that are absorbed by the digestive
tract. Blood enters the liver sinusoids from small branches of the portal vein and hepatic artery.
• A typical lobule is hexagonal in cross section. There are six portal areas, or hepatic triads, one at each of the six
corners of the lobule. A portal area contains three structures:
• (1) a branch of the hepatic portal vein,
• (2) a branch of the hepatic artery proper,
• (3) a small branch of the bile duct.

24. • Branches from the arteries and veins deliver blood to the sinusoids of adjacent lobules .
As blood flows through the sinusoids,
• hepatocytes absorb and secrete materials into the bloodstream across their
• exposed surfaces. Blood then leaves the sinusoids and enters the central vein of the
lobule. The central veins ultimately merge to form the hepatic veins that empty into the
inferior vena cava.
bile Secretion and Transport
• Bile is secreted into a network of narrow channels between the opposing membranes
of adjacent liver cells. These small passageways, called bile canaliculi, extend outward
through the liver lobule, away from the central vein.
• The canaliculi eventually connect with fine bile ductules (DUK-tūlz) that carry bile to a
bile duct in the nearest portal area. The right and left hepatic ducts collect bile from all
the bile ducts of the liver lobes.
• These ducts unite to form the common hepatic duct that leaves the liver. The bile within
the common hepatic duct may either
• (1) flow into the common bile duct that empties into the duodenum or
• (2) enter the cystic duct that leads to the gallbladder.