digest ii online
TRANSCRIPT
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ACCESSORY GLANDS
Pancreas, Liver, and gallbladder
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Pancreas
• Location
• Inferior to stomach
• Retroperitoneal
• Head is encircled by the duodenum; tail abuts the spleen
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Pancreas
• Soft triangular gland
• Endocrine function – secretes hormones
• Pancreatic islet cells
• Insulin / glucagon : blood sugar regulation
• Exocrine function – secretes enzymes
• Pancreatic juice : neutralizes stomach acid
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Pancreatic Juice
• Alkaline solution (pH 8), neutralizes chyme
• Enzymes
• Breakdown of sugars, proteins and fats
• Amylase, lipases and proteases
• Activated in the duodenum
Copyright © 2011 Pearson Education, Inc. Figure 22.27
Stomach
Pancreas
Epithelialcells
Trypsinogen(inactive)Chymotrypsinogen(inactive)Procarboxypeptidase(inactive)
Trypsin
Chymotrypsin
Carboxypeptidase
Membrane-boundenteropeptidase
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LIVER AND GALLBLADDER
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Liver
• Largest gland in the body
• Produces bile
• Four lobes—right, left, caudate, and quadrate
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Parts of the Liver
• Falciform ligament
• Separates the right and left lobes
• Suspends liver from the diaphragm
• Round ligament (ligamentum teres)
• Remnant of fetal umbilical vein
Copyright © 2011 Pearson Education, Inc. Figure 22.24a
Sternum
Liver
Right lobeof liver
Gallbladder
(a)
Bare area
Falciformligament
Left lobe of liver
Round ligament(ligamentum teres)
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Liver: Associated Structures
• Lesser omentum anchors liver to stomach
• Hepatic artery and vein at the porta hepatis
• Bile ducts
• Common hepatic duct leaves the liver
• Cystic duct connects to gallbladder
• Bile duct joining of common and cystic ducts
Copyright © 2011 Pearson Education, Inc. Figure 22.21
Jejunum
Mucosawith folds
Cystic duct
DuodenumHepatopancreaticampulla and sphincter
Gallbladder
Right and lefthepatic ducts of liver
Bile duct and sphincter
Main pancreatic ductand sphincter
PancreasTail of pancreas
Head of pancreas
Common hepatic duct
Major duodenalpapilla
Accessory pancreatic duct
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Liver: Function
• Liver lobules
• Functional units of liver
• Hexagonal shape
• Filter nutrient-rich blood
• Composed of hepatocytes (liver cells)
• Longitudinal central vein
Copyright © 2011 Pearson Education, Inc. Figure 22.25a, b
(a) (b)Lobule Central vein Connectivetissue septum
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Liver: Microscopic Anatomy
• Hepatocyte functions
• Process bloodborne nutrients
• Store fat-soluble vitamins
• Store glycogen
• Perform detoxification
• Produce bile
• Kupffer cells (hepatic macrophages) in liver sinusoids
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Bile
• Yellow-green, alkaline solution containing
• Bile salts
• Bilirubin: pigment formed from heme
• Cholesterol, neutral fats, phospholipids, and electrolytes
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Bile
• Enterohepatic circulation
• Recycles bile salts
• Bile salts duodenum reabsorbed from ileum hepatic portal blood liver secreted into bile
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The Gallbladder
• Muscular sac on the ventral surface of the liver
• Stores bile
• Releases bile via the cystic duct,
• flows into bile duct
• Bile secretion is stimulated by
• Exposure to HCl and fatty chyme
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Organ Coverings of the Abdominal Cavity
• Parietal peritonium
• Contacts abdominal wall
• Visceral peritonium
• Contacts abcominal organs
• Mesentary
• Double-layered tissue supporting organs
• Greater omentum
• Fatty sheet draped over organs
• Lesser omentum
• Connects liver to stomach
All abdominal organs are supported by coverings
Copyright © 2011 Pearson Education, Inc.
Copyright © 2011 Pearson Education, Inc. Figure 22.30d
(d)
Pancreas
LiverLesser omentum
Stomach
Duodenum
Transversemesocolon
Greater omentumMesentery
Jejunum
Visceral peritoneum
Urinary bladder
Transverse colon
Ileum
Parietal peritoneum
Rectum
Organ Coverings of the Abdominal Cavity
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Bacterial Flora
• Help to breakdown food
• Found in the colon
• Release irritating acids and gases
• Synthesize B complex vitamins and vitamin K