18 Jan 2016

Digestive system anatomy

Digestive System is a group of organs that convert food into energy to supply the entire body and eliminates waste material.

The Digestive system begins at the mouth /oral cavity, pharynx, esophagus, stomach, small intestines, large intestines, rectum, and ends at the anus.

There are few accessory organs that assist in digestion (Teeth, tongue, salivary glands, liver, gallbladder, and pancreas). 

Anatomy of Digestive System

The GI Tract (Gastrointestinal Tract) starts from the mouth, inside the mouth, there are many accessory organs that assist in the digestion of food are, 

     1. The tongue,
     2. The teeth,
     3. Salivary glands (Parotid, Sub-lingual and Sub-mandibular glands)

Teeth chop food into small pieces, then it is moistened by saliva then tongue pushes the food into the pharynx.

The pharynx is a funnel-shaped tube connected to the posterior end of the mouth. It moves the chewed food from the mouth to the esophagus.

The pharynx also plays a role in the respiratory system, as air from the nasal cavity, passes through the pharynx on it's way to the larynx and to the lungs. The pharynx contains a flap of tissue known as the epiglottis that acts as a switch to route food to the esophagus and air to the larynx.

The esophagus is a muscular tube connecting the pharynx to the stomach. cardiac sphincter is present in the junction between esophagus and stomach. 

The stomach is a muscular sac that is located on the left side of the abdominal cavity, just inferior to the diaphragm. It acts as a storage place for food so that it digests large meals properly. 

The stomach contains HCL (hydrochloric acid) and digestive enzymes that aids in breaking down the large substance into smaller substances. Then the digested material passes to the Small intestine via pyloric sphincter.

The small intestine is located just inferior to the stomach and takes up most of the space in the abdominal cavity. The entire small intestine is coiled like a hose and the inside surface is full of many ridges and folds. These folds are used to maximize the digestion of food and absorption of nutrients. 

By the time food leaves the small intestine, around 90% of all nutrients have been extracted from the food.

The small intestine is divided into,

     1. Duodenum

     2. Jejunum 

     3. Ileum

Accessory digestive organs found in the abdominal region are,
     1. Liver
     2. Gallbladder
     3. Pancreas

The liver is an accessory organ of the digestive system located to the right upper quadrant of the abdomen, the right side of the stomach, just inferior to the diaphragm and superior to the small intestine. 

The liver is the largest internal organ in the body. The liver has many different functions in the body, but the main function of the liver in digestion is the production of bile and its secretion into the small intestine (duodenum).

The gallbladder is a small, pear-shaped organ located just inferior to the liver. The gallbladder is used to store and recycle excess bile from the small intestine so that it can be reused for the digestion of subsequent meals.

The pancreas is a large gland located just inferior and posterior to the stomach. The pancreas secretes digestive enzymes into the small intestine to complete the chemical digestion of foods. The endocrine function of the pancreas is Insulin production. 

From Small intestine, the digested food passes to the large intestine. via Ileocecal valve.

The large intestine is a long, thick tube divided into,

      1. Cecum,
      2. Ascending colon,
      3. Transverse colon,
      4. Descending colon,
      5. Sigmoid colon
      6. Rectum
      7. Anus

The large intestine is located just inferior to the stomach and wraps around the superior and lateral border of the small intestine. The large intestine absorbs water and contains many symbiotic bacteria that aid in the breaking down of wastes to extract some small amounts of nutrients. Faeces in the large intestine exit the body through the anal canal.

Functions of the digestive system:
  • Ingestion
  • Secretion
  • Mixing and movement
  • Digestion
  • Absorption
  • Excretion

Common disease of Digestive system:

1. GERD – Stomach acid flows backwards causing discomfort


     2. Crohn’s disease - Inflammation that affects the lining of the digestive tract.


     3. Irritable bowel syndrome- Is a problem that affects the large intestine.


     4. Diverticulosis - Small, bulging pouches develop in the digestive tract.


     5. Colitis - Inflammation of the inner lining of the colon.


     6. Colon Polyp - A small clump of cells that forms on the lining of the colon.


Common Signs and Symptoms of Digestive system

     1. Abdominal pain

     2. Blood in the stool

     3. Bloating

     4. Constipation

     5. Diarrhea

     6. Heartburn

     7. Incontinence

     8. Nausea and vomiting


1.     Mouth                   - Oral / Stomato

2.     Lip                       - Labio / Cheilo

3.     Tooth                    - Dento / Odonto

4.     Tongue                 - Glosso / Linguo

5.     Uvula                   - Uvulo

6.     Salivary gland      - Sialo

7.     Gums                    - Gingivo

8.     Pharynx                - Pharyngo

9.     Esophagus            - Esophago

10.   Stomach                - Gastro

11.   Duodenum            - Duodeno

12.   Jejunum                - Jejuno

13.   Ilium                     - Ilio

14.   Liver                     - Hepato

15.   Gallbladder           - Cholecysto

16.   Common bile duct - Choledocho

17.   Bile                       - Chol

18.   Small Intestine     - Entero

19.   Colon                    - Colo

20.   Cecum                  - Ceco

21.   Sigmoid colon      - Sigmoido

22.   Rectum                 - Procto / Recto

23.   Anus                     - Ano     


1. CT - Computed tomography

2. ERCP - Endoscopic retrograde cholangiopancreatography

3. GERD - Gastroesophageal reflux disease

4. GI – Gastrointestinal

5. HCL - Hydrochloric acid

6. IBS - Irritable bowel syndrome

7. IBD - Inflammatory bowel disease

8. LFT - Liver function test

9. LLQ - Left lower quadrant

10. LUQ - Left upper quadrant

11. MRA - Magnetic resonance angiography

12. MRI - Magnetic resonance imaging

13. RLQ - Right lower quadrant

14. RUQ - Right upper quadrant


Test your Knowledge:


            A. Digestive System - Anatomy Quiz 

            B. Terminology Quiz