The Digestive System

DIGESTIVE SYSTEM

The digestive tract is also known as the Alimentary Canal or Gastrointestinal Tract (GI) – it consists of several organs responsible for the digestion and absorption of food.

FOOD JOURNEY THROUGH THE DIGESTIVE SYSTEM

FOOD —>—> MOUTH ( ingestion) —->—> teeth, tongue, salivary glands ( chewing , secretion and lubricating of food) —>—->PHARYNX —>—> ESOPHAGUS —>—> STOMACH —>—> SMALL INTESTINE —>—>duodenum, jejunum, and ileum —>—> LIVER —>–> GALLBLADDER —>—> PANCREAS —>—> LARGE INTESTINES —>—> cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon to the rectum ( excretion or defecation of waste materials)––>—> ANUS

 

MAIN ORGANS OF THE DIGESTIVE SYSTEM:

  1. Mouth
  2. Pharynx
  3. Esophagus
  4. Stomach
  5. Small Intestines
  6. Large Intestines
  7. Anus

ACCESSORY ORGANS OF THE DIGESTIVE SYSTEM:

  1. Tongue
  2. Teeth
  3. Salivary Glands
  4. Liver
  5. Gallbladder
  6. Pancreas

 

PROCESS OF DIGESTION:

A. Mouth or Oral Cavity The process of the digestion starts in the mouth with ingestion, where food is ingested. The mouth is consist of several accessory organs that aids in the digestion of food, namely: the tongue, teeth and the salivary glands.

  • Teeth. The teeth are designed to chew, grinding food into smaller particles.
  • Tongue. The tongue is a muscular organ covered with mucosa. The upper surface of the tongue has a rough texture because of the presence of the tiny bumps called papillae. Covering the surface of the tongue are the which allow you to determine the taste of your food (sweet, sour, bitter and salty). The tongue plays an important role in chewing and swallowing, and also in speech. The many nerves found in the tongue helps in transmitting taste signals to the brain.
  • Salivary Glands. The salivary glands produce saliva, which moisten and lubricates food. It contains amylase enzyme (ptyalin) that helps in digestion.

B. Pharynx
The pharynx, or throat, is a cone-shaped passageway of food from the mouth to the esophagus. . The pharynx also plays an important role in the respiratory system, Because the pharynx has two different functions, it contains a flap of cartilage known as the epiglottis that is located behind the tongue and in front of the larynx, It serves like a switch to direct food to the esophagus and air to the larynx. Epiglottis is in an upright position when at rest, thus allowing air to enter the larynx and lungs. It folds backward when swallowing to cover the opening of the larynx, thus food enters the esophagus instead of passing into the lungs.

C. Esophagus
The esophagus is a muscular tube that delivers the chewed food from the pharynx to the stomach.

D. Stomach -The stomach contains gastric enzymes and gastric juice, that help breaks food into smaller pieces, thus turning the bolus into a chyme; making it ready to pass into the small intestine. Hydrochloric acid also kills bacteria present in the food.

Parts of the stomach:

  • Cardia – also called the esophagastric junction. This is the notch where the esophagus meets with the stomach. This is where the food contents of esophagus empty into the stomach.
  • Fundus – is the uppermost curvature of the stomach.
  • Body – largest part of the stomach.
  • Pylorus -This is the part where the gastric contents empties out of the stomach and passes into the duodenum, of the small intestine.

 

E. Small Intestine
From the stomach, food enters the duodenum, the first part of the small intestine. It then enters the jejunum, (approximately 8 feet long) and then travels to the ileum, the final segment of the small intestine (approximately 12 feet long). The small intestine terminates into the cecum. It is in the small intestine where much of the digestion and absorption of food takes place with the help of the digestive enzymes and bile secreted in the small intestine. The primary responsibility of the small intestine is the absorption of nutrients and minerals found in food. The small intestine terminates into the cecum.

  • Liver
    The liver weighs about 3-4 pounds and is the largest internal organ and the largest gland in the body. The liver has many functions, but the main function of the liver in the process of digestion is the production of bile into the small intestine, which plays an important role in emulsifying fats.
  • Gallbladder
    The gallbladder stores and concentrates bile and then contracts to release it into the duodenum (small intestine) to aid in the absorption and digestion of fats.
  • Pancreas
    The pancreas is a gland that secretes pancreatic juice that contains digestive enzymes that helps in digesting and breaking down fats, proteins and carbohydrates. The pancreas also secretes insulin into the bloodstream which is produced by the Islets of Langerhans. Insulin plays an important role in the metabolism of carbohydrates.

F. Large Intestine
The large intestine or colon is a long, thick tube (approximately 5 feet long). The large intestine is made up of the cecum (where the appendix is attached), the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum. The large intestine absorbs water and eliminates waste materials from the body.

  • Ileocecal Valve – prevents contents of the large intestine from entering the ileum (lower part of small intestine).

G. Rectum
The rectum intestinum (Latin for “straight intestine”) is an 8-inch chamber which is a continuation of the sigmoid colon, and connects to the anus. It holds the stool in place until it is ready to be evacuated.

H. Anus
The anus is the end part of the digestive tract where solid or liquid waste and gas are excreted. Excretion of waste is a process known as defecation.

 

CONDITIONS OF THE DIGESTIVE SYSTEM:

APPENDICITIS –

CHOLECYSTITIS

CIRRHOSIS

CONSTIPATION

CROHN’S DISEASE

DIARRHEA –

DIVERTICULITIS

DIVERTICULOSIS

DUMPING SYNDROME

GALLSTONES

GASTRITIS

GASTRO ESOPHAGEAL REFLUX DISEASE

HEMORRHOIDS

HEPATITIS

  1. Hepatitis A
  2. Hepatitis B
  3. Hepatitis C
  4. Hepatitis E

HIATAL HERNIA

PANCREATITIS

PEPTIC ULCER DISEASE

  1. Gastric Ulcers
  2. Duodenal Ulcers
  3. Dumping Syndrome

ULCERATIVE COLITIS

 

DIAGNOSTIC PROCEDURES:

  1. Colonoscopy
  2. Sigmoidoscopy
  3. Barium Swallow ( upper GI tract study)
  4. Barium Enema ( lower GI tract study)
  5. Liver Biopsy
  6. Endoscopy
  7. ERCP (Endoscopic Retrograde Cholangiopancreatography)
  8. Endoscopic Ultrasound (EUS)

 

*** Many types of Digestive System Disorders can be prevented by following a healthy lifestyle.

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