Digestive System Part 2

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Digestive SystemPart 2

• Anatomy 220

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Objectives- Part 1

• Describe the relative placement of the following
  structures how they fit into the food-digestion
  pathway
• Stomach, liver, gall bladder, pancreas, small
  intestine
• Describe chemical digestion in the stomach
  listing the secretions, describing their
  sources their basic role in digestion
• Describe how the stomach is protected from these
  secretions

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Objectives- Part 2

• Describe the cause of most peptic ulcers
• Describe the composition role of villi
• know the organs and ducts associated with the
  biliary tree their contributions to the
  breakdown of fats, and be able to trace the
  pathway of bile

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Objectives- Part 2

•         

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Functions

• Ingestion
• Transport
• Digestion
• Absorption
• Compaction
• Elimination

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Overview

• A hollow tube 25 feet (7.5m) long
• Changes shape
• Several glands
• secrete into
• tube

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4 Layers

• From outer to deep
• Serosa (peritoneum) CT
• Muscular layer (2 parts)
• Longitudinal layer
• Circular layer
• Submucosa
• Muscosa

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Stomach
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Gastric Epithelial Cell-types
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2
3
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Why doesnt stomach digest itself?

• Mucous from Mucous cells coats and protects

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Peptic Ulcers
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Digestion in the stomach

• Two types of digestion
• Chemical caused by the 4 different secretions
• Physical caused by contraction of muscular layer.
  Result is churning and mixing of bolus with
  gastric secretions

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What do you think?

• Why does the stomach have an extra layer of
  muscle (the oblique layer) compared to the rest
  of the GI tract? 

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Pyloric Sphincter

• Location -End of stomach and beginning of
• duodenum

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Small Intestine

• About 21 ft. long
• Divided into three parts
• Duodenum 1 ft.
• Jejunum 8 ft.
• Ileum 12 ft.

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Small Intestine
Duodenum
Jejunum
Ileum
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Small Intestines

• Most absorption of _________ occur here

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Lining of Small Intestines

• Inside lining has circular folds called plicae
  increase surface area

Plicae
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Lining of Small Intestines

• Entire surface has microscopic _______ called
• villi
• (singular villus)

Villus
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A Villus

• A villus has
• epithelium
• arteriole
• capillary
• venuole
• lymph duct

• Food goes
• across epithelium
• into capillary
• into venuole
• portal v.
• liver

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What do you think?

• Why is the small intestine so much longer than
  the stomach?

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Duodenum
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Duodenum

• C-shaped
• 1 foot long
• Mainly on right superior side
• Receives secretions from two glands
• Liver bile (detergent)
• Pancreas bicarbonate and proteolytic enzymes

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Biliary Tree
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Biliary Tree
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Pancreatic Duct
Common Bile Duct
PancreaticDuct
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Biliary Tree
LIVER
GALL BLADDER
DUODENUM
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Biliary Tree
LIVER
hepatic ducts
GALL BLADDER
DUODENUM
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Biliary Tree
LIVER
hepatic ducts
common hepatic duct
GALL BLADDER
DUODENUM
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Biliary Tree
LIVER
hepatic ducts
cystic duct
common hepatic duct
GALL BLADDER
DUODENUM
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Biliary Tree
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Biliary Tree
LIVER
hepatic ducts
cystic duct
common hepatic duct
GALL BLADDER
common bile duct
DUODENUM
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Biliary Tree
LIVER
hepatic ducts
cystic duct
common hepatic duct
GALL BLADDER
common bile duct
DUODENUM
pancreatic duct
PANCREAS
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Liver
Upper Right Quadrant
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Liver
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Liver
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Gallstones