Medbroadcast  Powered by MediResource
 Search

Go
 Browse alphabetically
ABCDEFGHIJKLMN
OPQRSTUVWXYZ
HEALTH TOPICS
Family & Child Health
Men's Health
Women's Health
Seniors' Health
Addiction
Allergy
Ankylosing Spondylitis
Arthritis (Rheumatoid)
Asthma
Atrial Fibrillation
Baby Health
Back Health
Bedwetting
Bladder (Overactive)
Brain Health
Cancer
Childhood Vaccinations
Cholesterol
Crohn's & Colitis
Cold and Flu
COPD NEW!
Cosmetic Procedures
Depression NEW!
Diabetes
Digestive Health
Ear Health
Eating Disorders
Eye Health
Flu (Seasonal)
Fertility
Fitness
Healthy Skin
Heart
High Blood Pressure
HPV
Hyperhidrosis
Incontinence
Infection
Kidney Health
Lung Health
Medications and your Health
Menopause
Mental Health
Multiple Sclerosis NEW!
Natural and Complementary Therapy
Nutrition
Obesity
Oral Care
Osteoarthritis of the Knee NEW!
Pain
Pregnancy
Psoriasis
Psoriatic Arthritis (PsA)
Seasonal Health
Sexual Health
Sleep Health
Stroke Risk Reduction
Smoking
Weight Management
Workplace Health
Yeast Infection
All health channels

STAY CONNECTED
RESOURCES
Ask an Expert
Clinical Trials
Find a Specialist
Health features
News
Tools


Condition Info Drug Info Tests and Procedures Natural Products Ask an Expert Support Groups Clinical Trials
Home Bookmark Page Send to a Friend Sante Chez Nous Subscribe
Digestive Health > Healthy digestion > Gastrointestinal tract: anatomy
Digestive Health
Nausea / upset stomach
Heartburn / indigestion
Diarrhea
Constipation/Staying regular
Healthy digestion
Digestive diseases
Gastrointestinal tract: anatomy
What's fat got to do with it?
Get active and keep things flowing through your colon
Need help with your digestive health?
Reset your body
Surprisingly simple day-to-day ways to help promote heart health
Detox diet: do or don't?
Regular screening tests can be a lifesaver
Digestive Health resources
Health features
Health tools
Related conditions
Related medications
Natural products



Gastrointestinal tract: anatomy

The gastrointestinal (GI) tract is a passageway that begins at the lips and ends at the anus (Figure 1). Its purpose is to transport and digest food. Along the way, the passageway changes character because different functions are required at different points.

In the uppermost portion, the teeth begin the process of digestion by grinding food into small fragments. The esophagus delivers the food to the stomach where strong acid further breaks up and degrades the swallowed material.

Gastrointestinal tract

Figure 1

Gastrointestinal tract

Small amounts of the liquified food called chyme are then delivered in spurts from the stomach into the duodenum where they are mixed with bile from the liver (via the bile ducts) and pancreatic juice (via the pancreatic duct). Bile aids in the breakdown and digestion of fat, while the pancreatic enzyme amylase fragments starches into smaller molecules. The pancreas also releases a fluid into the duodenum, which neutralizes the acidic stomach contents. This neutral bile/amylase/fragmented food substance passes to the upper small intestine for the next phase of digestion. It is moved along by peristalsis, worm-like contractions of the intestine.

The small intestine is so named because its calibre is small, about one inch in diameter. The term small creates some confusion because, in terms of length, it is not small at all. In fact, it normally measures nearly 23 feet in length! The small intestine's job is absorption of food. The body gains access to the food that we consume by means of absorption of microscopic particles of food through the wall of the small intestine. Vitamins and minerals and large amounts of fluid are also absorbed by the small intestine and pass into the bloodstream for distribution to the rest of the body.

By the time the intestinal contents reach the large intestine, most of its nutritional value has been extracted, leaving a watery waste product. The role of the large intestine is fluid absorption from the remaining waste and compaction and storage of what is left. Expulsion of the waste (feces, stool) is generally under voluntary control and is undertaken when socially convenient.

Large intestine or colon

Figure 2

Large intestine or colon

The large intestine is so named because it is wider than the small intestine, not because it is longer. It is much shorter than the small intestine, measuring about 5 feet. Another name for the large intestine is the colon. It begins in the lower portion of the right side of the abdomen and travels up the right side to turn across the midline and back down the left side much like a square picture frame (Figure 2). As stool moves from the cecum to ascending colon, transverse colon, descending colon, sigmoid colon, and finally rectum, it becomes less watery and more compacted. The rectum is the last foot or so of the large intestine and it lies surrounded by the bones of the pelvis. At the very bottom of the rectum is the anus, where lie the sphincter muscles that control the opening of the bowel.

 
Michael E. Pezim, MD


Advertisement

Did you find what you were looking for on our website? Please let us know.

Hot Topics - Bedwetting, Depression, Flu (Seasonal), Healthy Skin, Incontinence, Multiple Sclerosis, Psoriasis, Stroke Risk Reduction

Condition and disease information is written and reviewed by the MedBroadcast Clinical Team.


The contents of this site are for informational purposes only and are meant to be discussed with your physician or other qualified health care professional before being acted on. Never disregard any advice given to you by your doctor or other qualified health care professional. Always seek the advice of a physician or other licensed health care professional regarding any questions you have about your medical condition(s) and treatment(s). This site is not a substitute for medical advice.
© 1996 - 2014 MediResource Inc. - MediResource reaches millions of Canadians each year.