Copyright © 2009 Pearson Education, Inc. Figure 14.1

Digestive System Chapter 14

Pharynx• Passageway for food and air• Participates in swallowing

Esophagus• Moves food from pharynx

to stomach

Salivary glands• Saliva moistens food• Bicarbonate maintains pH• Amylase digests starch• Lysozyme inhibits bacteria

ACCESSORY ORGANS:

Liver• Produces bile• Performs various functions

associated with processingand storing nutrients

Pancreas• Secretes digestive enzymes

into small intestine• Secretes bicarbonate into

small intestine to neutralizestomach acid

Gallbladder• Stores and concentrates bile

Mouth• Teeth chew food• Tongue positions and

tastes food

ORGANS:

Appendix• No known digestive function

Stomach• Stores and mixes food• Begins chemical digestion of

protein by enzymes and acid• Regulates delivery to the

small intestine

Anus• Expels undigested material

Rectum• Passageway for feces

Sigmoid colon• Stores feces

Large intestine• Absorbs the last of the water

and nutrients• Stores waste material

Small intestine• Digests proteins, fats,

and carbohydrates• Absorbs most of the water

and nutrients• Secretes digestive hormones

and enzymes

Copyright © 2009 Pearson Education, Inc. Figure 14.2

Gastrointestinal (GI) Tract Wall

Lumen

Circularlayer

Longitudinallayer

Lymph vessel

Serosa• Connective tissueouter covering• Protects and anchorsthe digestive tract

Mucosa• Mucous membrane layer• Lines the digestive tract

Submucosa• Connective tissue layer• Contains blood vessels, lymph vessels,and nerves

Muscularis• Two layers of smooth muscle• Responsible for motility of thedigestive tract

VeinArteryNerve

Copyright © 2009 Pearson Education, Inc. Figure 14.3a

Motility: Peristalsis

Copyright © 2009 Pearson Education, Inc. Figure 14.3b

Motility: Segmentation

Copyright © 2009 Pearson Education, Inc. Figure 14.5

Salivary Glands

Copyright © 2009 Pearson Education, Inc. Figure 14.6a

Swallowing

Copyright © 2009 Pearson Education, Inc. Figure 14.6b

Swallowing

Copyright © 2009 Pearson Education, Inc. Figure 14.7a–b

Structure of the Stomach Wall

Copyright © 2009 Pearson Education, Inc.

Stomach Function

Specific cells secrete gastric juice Hydrochloric acid

Produces a pH of about 2; breaks down large bits of food

Mucus

Protects stomach lining from acid

Pepsinogen

With acid, begins protein breakdown as pepsin

Copyright © 2009 Pearson Education, Inc. Figure 14.7

The Stomach

Copyright © 2009 Pearson Education, Inc. Figure 14.8

Peristalsis

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Small Intestine

Functions Digestion

Neutralizes acid from stomach

Adds digestive enzymes and bile

Breaks proteins, carbohydrates, and lipids to absorbable materials

Absorption

95% of food absorbed in small intestine

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Small Intestine

Structure Regions

Duodenum

Jejunum

Ileum

Mucosa adaptations

Villi containing blood and lacteal capillaries

Copyright © 2009 Pearson Education, Inc. Figure 14.9a–b

The Wall of the Small Intestine

Copyright © 2009 Pearson Education, Inc. Figure 14.9c

The Wall of the Small Intestine

Copyright © 2009 Pearson Education, Inc. Table 14.1

Major Digestive Enzymes

Copyright © 2009 Pearson Education, Inc. Figure 14.10

Accessory Organs: Aid Digestion and Absorption

Esophagus Liver• Produces bile

(water and electrolytes,cholesterol, bile salts,lecithin, andpigments)

Gallbladder• Stores and

concentrates bile• Delivers bile to the

duodenum via thecommon bile duct

Pancreas• Secretes enzymes

(proteases, amylase,lipase)

• Produces sodiumbicarbonate

• Delivers these products tothe duodenum via ducts

Stomach

Pancreatic duct

Commonbile duct

Duodenum

Copyright © 2009 Pearson Education, Inc. Figure 14.11

Accessory Organs: Aid Digestion and Absorption

Copyright © 2009 Pearson Education, Inc. Figure 14.12

Large Intestine

Sigmoid colon

Descendingcolon

External analsphincter(skeletal muscle)

Anus Anal canal

Rectum

Internal analsphincter(smooth muscle)

Appendix

Cecum

Ileocecalvalve

Ascendingcolon

Transversecolon

Smallintestine

Copyright © 2009 Pearson Education, Inc. Figure 14.13

Absorption of Proteins and Carbohydrates

Copyright © 2009 Pearson Education, Inc.

Endocrine and Nervous Systems Regulation of Digestion

Regulation dependent on volume and content of food Nervous system

Stretch receptors in stomach

Hormones

Gastrin

Secretin

Cholecystokinin (CCK)

Copyright © 2009 Pearson Education, Inc. Figure 14.14

Absorption of Fats

Copyright © 2009 Pearson Education, Inc. Figure 14.15

Nutrients: Utilized or Stored Until Needed

Copyright © 2009 Pearson Education, Inc. Figure 14.16

Food Guide Pyramid

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Disorders of the Digestive System

Disorders of the GI tract Lactose intolerance

Diverticulosis

Colon polyps

Disorders of accessory organs Hepatitis

Gallstones

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Disorders of the Digestive System

Malnutrition

Obesity

Eating disorders Anorexia nervosa

Bulimia