Digest ii online

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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

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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