Kevin Yocum Digestive System 2

8/13/2019 Kevin Yocum Digestive System 2

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Chapter 25

The Digestive System

Kevin Yocum

Fall 2013


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Objectives for 25.4

Describe the anatomy of the liver, gall

bladder, bile duct, and pancreas.

Describe the digestive secretions of

the liver, gall bladder, and pancreas.

Explain the hormonal regulation of theliver and pancreas.


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The Liver

Hepatic lobules Central vein

Hepatic sinusoids

Hepatic portal system

Bile duct Hepatic ducts

Cystic duct


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Fig. 25.19

Gross Anatomy of the Liver

Notes: From Saladin 6thEd.


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Fig. 25.20Microscopic

Anatomy of

the Liver


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The Gall Bladder

Stores and concentrates bile

Bile Bilirubin

Urobilinogen

Bile salts

Lecithin Aid in fat digestion/absorption


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The Pancreas

Pancreatic juice


Fig. 25.23


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Fig. 25.21

Gross Anatomy of GB and Pancreas



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Regulation of Secretion

Acetylcholine (ACh) Vagus and enteric nerves

Pancreatic acini

Cholecystokinin (CCK) Duodenal mucosa and proximal jejunum

Intestinal fats

Secretin Sodium bicarbonate


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Checkpoint Questions

The hepatic and cystic ducts converge

to form the _______.

The liver receives 70% of its blood from

the ______________.

_______ stimulates the liver andpancreatic ducts to secrete sodium

bicarbonate.


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Checkpoint Answers

The hepatic and cystic ducts converge

to form the bile duct.

The liver receives 70% of its blood from

the hepatic portal vein.

Secretinstimulates the liver andpancreatic ducts to secrete sodium

bicarbonate.


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Objectives for 25.5

Describe the complete anatomy of the

small intestine.

Differentiate between intestinal

mucosa and stomach mucosa.

Define contact digestion. Describe intestinal movements.


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Gross Anatomy of the SI

Duodenum

Duodenojejunal flexure

Jejunum

Ileum Peyer patches

Ileocecal junction



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Microanatomy of the SI

Circular folds

Villi

Enterocytes and goblet cells

Lacteal

Intestinal crypts and intestinal juice

Contact digestion Microvilli

Brush border enzymes


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Fig. 25.25


Intestinal

Villi


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Intestinal Motility

Segmentation

Peristalsis


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Checkpoint Answers

The second section of the small

intestine is called thejejunum.

Lipids are absorbed in the small

intestines due to the presence of

lacteals. Movement in which stationary ring-like

constrictions appear at several places

along the SI is called segmentation.


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Objectives for 25.7

Describe the anatomy of the large

intestine.

Contrast LI mucosa with SI mucosa. State the significance of intestinal

bacteria.

Discuss the types of colon

contractions.

Link neurology with defecation.


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Microanatomy of LI

Simple, columnar epithelium

Anal canal Non-keratinized stratified squamous

epithelium

No circular folds or villi

Crypts Deep

Many goblet cells


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Bacterial Flora and Gas

Bacterial flora 800 species of bacterial flora in LI

Digest cellulose, pectin, plant polysaccharides

Gas

Flatus 7-10 Liters, of which 500ml/day is expelled


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Absorption and Motility

12-24 hours from mouth to anus

Reabsorption of water and electrolytes

(ex: NaCl) 75% water

25% solids Fiber, fat, proteins, salts, mucus

Haustral contractions and mass

movements


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Defecation

Intrinsic reflex Myenteric nerve plexus

Parasympatheticreflex Spinal reflex



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Checkpoint Questions

The first section of the large intestine is

called the _____.

Expelling of gas from the large intestine

is known as ____.

The defecation reflex that operatesentirely from the myenteric nerve plexus

is the ___________________.


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Checkpoint Answers

The first section of the large intestine is

called the cecum.

Expelling of gas from the large intestine

is known as flatus.

The defecation reflex that operatesentirely from the myenteric nerve plexus

is the intrinsic defecation reflex.


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References

Saladin, Kenneth (2012). Anatomy and

Physiology, The Unity of Form and

Function, Sixth Ed. New York, NY:McGraw-Hill.

Kevin Yocum Digestive System 2

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