Note: There are several subpages for the the Digestive System, including GI Functions & Structures, GI Clinical View, GI in the News, and GI Review

Here is a video introducing us to what happens to food once we swallow it. In addition to the resources on this page, be sure to check out the sub page, labeled "Structures." And here is a video which is purely entertainment of a man who seems to have gained an abnormal ammount of control over his stomach and esophagus.

Learning Objectives

Learn the functions and tissues of the digestion system.
Learn the passageway of the digestive system, the Alimentary Canal.

Notes, Pictures & Videos

Case Study

Check out these cool abdominal radiology case studies such as the esophageal abnormality as shown by this barium swallow (Case study 8) or the woman with a long history of indigestion (Case study 13) Enjoy!

Glossary

Mesenteries:are folds of peritoneum that support and stabilize the intraperitoneal GI tract organs.

Greater omentum: extends inferiorly like an apron from the greater curvature of the stomach and covers most of the abdominal organs. It often accumulates large amounts of adipose connective tissue.
Lesser omentum : connects the lesser curvature of the stomach and the proximal end of the duodenum to the liver.
GI Tract organs include: Oral cavity, Pharynx, Esophagus, stomach, small intestine, large intestine
(Old Pete Eats Some Soft Lettuce) Just a little neumonic device
The abdominal organs are of the GI tract are supported by serous membranes
Parietal peritoneum- lines the inside surface of the body wall
visceral peritoneum- reflects and covers the surface of internal organs
intraperitoneal organs- abdominal organs that are completely surrounded by visceral peritoneum (stomach, jejunum & ileum of the small intestine, cecum, appendix)
retroperitoneal organs- abdominal organs that lie behind the parietal pertineum ( most of the duodenum, pancreas, kidneys, ascending colon, descending colon, rectum)
histology- study of tissues The GI tract from the esophagus to the large intestine is a tube of four centric layers called tunics.
Lumen (not a tunic)- space within a tube
Mucosa- has absorptive and secretory functions
submucosa- is a dense irregular connective tissue
muscularis- contains two layers of muscle (an inner circular layer and an outer longitudinal layer) these are responsible for peristalsis
Outer most tunic may be either an adventitia or serosa
adventitia is composed of loose connective tissues with dispersed collagen and connective tissue with dispersed collagen and elastic fibers. ex: retropertitoneal portion of the duodenum
serosa has the same components as adventitia but is covered by visceral peritoneum. ex: intraperitoneal organs such as the stomach are covered in serosa
stomach- has four regions. The "cardia" which is a small, narrow, superior entryway into the stomach lumen from the esophagus. The "fundus" is the dome-shaped region lateral and superior to the esophageal connection with the stomach. The "body" is the largest region of the stomach and is inferior to the fundus. The "pylorus" is a narrow medially directed funnel shaped pouch that forms the terminal region of the stomach.
Uvula- conic projection from the posterior edge of the middle of the soft palate; composed of connective tissue containing a number of racemose glands and some muscle fibers.

Connections to other body systems

The Autonomic Nervous System:

• Sympathetic system will decrease peristalsis of the GI tract.
  
• Parasympathetic system will stimulate the peristalsis of the GI tract.
  

Cells:

• The digestive helps to break down food into nutrients/vitamins which the body needs especially cells to metabolize.

Nerves:

• Extrinsic (outside) nerves come from the brain or spinal cord to the digestive system. They release two chemicals to help the muscles of the digestive system to contract and relax to help the food move through the tract.
  

Immune System:

• The digestive system plays a prominent part in the Immune System. Thanks to the ph level of the stomach it creates a fatal environment for many microorganisms. Also the bile and saliva contain enzymes that help neutralize many microorganisms. Also the intestines have a health-enhancing bacteria that helps to protect overgrowth of other dangerous bacteria.