Digestion C

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Digestion C

• Chapter 22

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Accessory Structures

• Last week we talked about
• Teeth
• Tongue
• Salivary glands
• Today we will cover
• Pancreas
• Gall bladder
• Liver

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Pancreas

• Assists in chemical digestion
• Enzyme secretion
• Assists in neutralizing acid chyme
• 15 cm long
• Secretes into duodenum
• Exocrine (99) Endocrine gland (1)
• Structure
• Head
• Broad portion residing w/in loop of duodenum
• Body
• Elongated portion inferior to stomach
• Tail
• Blunt end adjacent to spleen

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Pancreas
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Pancreas
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Pancreas Function

• Produce pancreatic juice
• Sodium bicarbonate
• Neutralizes acid chyme
• Enzymes
• Pancreatic Amylase- Carbohydrates
• Pancreatic lipases- lipids
• Trypsin chymotrypsin- proteins

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Pancreatic Secretory Structures

• Secretion enter duodenum via ducts
• 2 ducts
• Pancreatic duct
• Main delivery duct
• Joins common bile duct from liver
• Duodenal (aka Hepatopancreatic) ampulla
• Accessory duct
• Smaller, superior duct

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Pancreatic Accessory Duct
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Hepatopancreatic ampulla
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Pancreas Histology

• Lobulated gland
• Glandular epithelial cells
• 99 exocrine
• Acinar cells- secrete digestive enzymes
• 1 endocrine- hormones
• Islets of Langerhans
• Beta cells (60)- Insulin
• Alpha Cells (25)- Glucagon
• Delta Cells (15)- Somatostatin

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Lobulate
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Acinar Cells
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Endocrine
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Liver

• Hepat liver
• Largest abdominal organ (3 lbs)
• Aids in digestive function
• Lobed structure
• Highly vascularized

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Liver
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Liver Digestive Function

• Metabolic regulation
• Hematological Function
• Bile synthesis secretion

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Metabolic Regulation

• Regulates carbohydrate, lipid, protein
• All blood leaving digestive tract travels
  directly to liver
• Hepatic portal vein
• Hepatocytes- liver cells
• Monitor adjust blood nutrients
• Remove store excess nutrients
• Detoxify blood

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Hematological Function

• Regulates blood composition
• Kupffer cells- phagocytic cells
• Remove old or damaged blood cells, cellular
  debris pathogens
• Heavy metals
• Produce blood proteins

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Bile synthesis secretion

• Breakdown product of hemoglobin pigment (RBC)
• Functions
• Neutralize acid chyme
• Emulsify lipids
• Breaks lipids into smaller lipid units
• Products stored in Gall Bladder

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Liver Anatomy

• 4 Lobes
• Large right left lobes
• Small caudate quadrate lobes

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Right Left Lobes
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Right Left Lobes
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Caudate Quadrate lobes
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Caudate Quadrate lobes
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Blood Supply

• High rate of profusion
• 25 of total cardiac output
• 2 blood sources
• Hepatic artery
• Blood supply from heart to liver
• Oxygen rich
• Hepatic portal vein
• Blood from the intestines to liver
• Nutrient rich, oxygen poor
• Liver processes incoming blood from GI tract

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Liver Histology

• Hepatocytes- liver cells
• Arranged into columns around large central vein
• Hexagonal shaped cell grouping
• spokes on a wheel
• Lobule
• Functional unit of liver
• Hexagonal arrangement
• 100,000 lobules/ liver

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Central Vein
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Hepatocyte functional unit
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Sinusoids

• Extensions of blood vessels between columns of
  hepatocytes
• Carries blood to be processed past hepatocytes
• Site of Kupffers cells
• Extend between the cells inside the lobules

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Liver Fluid Movement

• Blood enters via
• Hepatic portal vein (GI tract)
• Hepatic artery (heart)
• Both vessels branch into smaller vessels to
  supply each liver lobule
• Blood enters lobules at periphery
• Travels down sinusoids passing hepatocytes
• Processed blood drains into central vein
• All central veins unite to form hepatic vein
• Delivers processed blood to the heart

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Bile Canaliculi

• Narrow intercellular channels draining Bile
  produced by hepatocytes
• Bile flows away from central vein toward lobule
  perifery
• Collected by bile duct

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Hepatic Triad

• portal triad
• Arrangement of vessels at lobule periphery
• Branch of
• Hepatic portal vein
• Hepatic artery
• Bile duct

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Hepatic Triad

• Hepatic Artery
• Bile Duct

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Gall Bladder
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Bile Drainage

• Right hepatic ducts
• Collects bile from ducts on right side of liver
• Left hepatic ducts
• Collects bile from bile ducts on left side of
  liver
• Common hepatic duct
• Union of rt lt hepatic ducts
• Cystic duct
• Duct from gall bladder
• Common bile duct
• Union of cystic duct common hepatic duct
• Drains into duodenum
• Hepatopancreatic ampullae

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Bile Drainage
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Gallstones

• Bile contains water, cholesterol, fats, bile
  salts, proteins, bilirubin (waste)
• Bile with high concentrations of cholesterol,
  bile salts, or bilirubin can harden into
  gallstones
• Cholesterol stones- yellow green (80)
• Pigment stones- bilirubin

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Gallstones
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Clinical Application

• Liver Cirrhosis
• Scarring of liver
• Formation of fibrous scar tissue associated with
  destruction of normal liver architecture
• Only 30 of patients survive 5 yrs past
  diagnosis
• Most common reason for liver transplants

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Leading Causes

• 2001 7th leading cause of death
• Alcoholism
• 50 of all Cirrhosis
• Hepatitis C
• 1/70 persons
• 30 will develop cirrhosis

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Liver Cirrhosis