The Digestive System

Introduction

• This comprises organs that break down and digest food, and remove unabsorbed wastes from the body. Its main feature is the alimentary canal (gut) measuring about 30 feet (9m) in length.

Anatomical Structure Overview 1

• Mouth cavity: Teeth, tongue, salivary glands, and other structures begin processing food for swallowing.

• Esophagus: Connects the throat and the stomach. Food is moved by an action called “peristalsis”.

• Stomach: Food is churned, disinfected, and begins to digest.

Anatomical Structure Overview 2

• Sphincters: Rings of muscle that close at the junction of the stomach, the duodenum, and the anus.

• Digestive juices: Saliva, gastric, sm. Intestine, and pancreatic juices contain enzymes for digesting specific food substances.

• Small intestine: Approx 21 ft (6.5m) in length, and connects the stomach and lg. intestine. Subdivisions (beginning from the stomach) are the duodenum, the jejunum, and ileum. Most digestion occurs here.

Anatomical Structure Overview 3

• Large intestine: Approximately 5 ft (1.5m) in length, and runs from the ileum to the rectum. Main sections are the cecum, the ascending, transverse, and descending colon, and the sigmoid flexure.

• Appendix: A narrow tube projecting from the cecum.

• Rectum: Extends from the sigmoid flexure and ends at the anus.

Anatomical Structure Overview 4

• Liver: This large organ in the upper part of the abdomen secretes bile and stores vitamins.

• Gall bladder: This sac, located behind the liver, stores bile to be released into the duodenum.

• Pancreas: A large gland that secretes insulin and pancreatic juice into the duodenum.

DIGESTIVE SYSTEM: KEY DIAGRAM

1. Salivary gland

2. Teeth

3. Esophagus

4. Stomach

5. Liver

6. Pancreas

7. Gall bladder

8. Duodenum

9. Jejunum

10. Ileum

11. Cecum

12. Colon

13. Appendix

14. Rectum

15. Anus

DIGESTIVE SYSTEM I

1. Liver

2. Stomach

3. Small Intestine

4. Large Intestine

4a. Ascending Colon

4 b. Transverse Colon

DIGESTIVE SYSTEM II

1. Kidneys

2. Descending Colon

3. Ilium

4. Anus

5. Rectum

6. Appendix

7. Sacrum

8. Ascending Colon

POSITION OF DIGESTIVE SPHINCTERS

1. Esophageal sphincter

2. Cardiac sphincter

3. Pyloric sphincter

4. Sphincter of the hepatopancreatic

ampulla

5. Ileocecal valve

6. Anal sphincter

KEY STRUCTURES OF THE STOMACH

1. Cardiac notch

2. Cardiac portion

3. Fundus

4. Body

5. Angular notch

6. Pyloric portion

7. Pyloric sphincter

8. Pylorus

9. Greater Curvature

10. Lesser Curvature

DIGESTIVE JUICES

1. Mouth: Chewing helps to break down food

2. Stomach: Enzymes in gastric juice further break food down

3. Sm. Intestine: Enzymes in pancreatic and intestinal juices convert proteins into amino acids

4. Absorption through intestinal lining into the portal (liver) system

5. Portal vein

6. Liver: Amino acids made into useful proteins, stored as fat, or excreted as urine

INTESTINAL STRUCTURES

1. Sm. Intestine

1a. Duodenum

1b. Jejunum

1c. Ileum

2. Lg. Intestine

2a. Cecum

2b. Appendix

2c. Ascending colon

2d. Transverse colon

2e. Descending colon

2f. Anus

GALL & BILIARY TREE

1. Esophagus

2. Liver

3. Stomach

4. Hepatic duct

5. Cystic duct

6. Gall bladder

7. Common bile duct

8. Pancreas

9. Pancreatic duct

10. Duodenum