Overview of the Digestive System and Its Functions

Digestive System

Group of organs converting food into usable form.

Gastrointestinal Tract

Another name for the digestive system.

Alimentary Canal

Connecting chain of organs in digestion.

Ingestion

Taking in food or water.

Digestion

Breaking food down into nutrients.

Absorption

Nutrients absorbed using intestinal enzymes.

Elimination

Urination and defecation of waste.

Mechanical Means

Physical processes altering food composition.

Chemical Means

Chemical processes breaking down food.

Main Organs

Organs food passes through in digestion.

Accessory Organs

Organs aiding digestion but not in food passage.

Pharynx

Throat area connecting mouth to esophagus.

Teeth

Mechanical breakdown of food in mouth.

Salivary Glands

Produce saliva to aid digestion.

Liver

Processes nutrients and produces bile.

Carbohydrates

Primary energy source, converted to glucose.

Proteins

Essential for building and repairing tissues.

Vitamins

Regulatory chemicals for growth and body control.

Roughage

Fiber that speeds up digestion.

Calcium

Mineral essential for bones and teeth.

Iron

Mineral needed for red blood cell formation.

Colon

Includes ascending, transverse, descending, and sigmoid sections.

Rectum

Final section of the digestive tract before anus.

Liver

Upper right abdominal organ, below diaphragm.

Gallbladder

Stores bile under the liver, aids fat digestion.

Pancreas

Behind stomach; produces digestive enzymes and insulin.

Spleen

Upper left abdominal organ, near stomach.

Mouth

Entry point for food; begins digestion process.

Saliva

Contains ptyalin; starts carbohydrate digestion.

Tongue

Manipulates food; aids in chewing and taste.

Esophagus

Muscular tube transporting bolus to stomach.

Peristalsis

Involuntary muscle contractions moving food downward.

Stomach

J-shaped organ; churns food and digests chemically.

Chyme

Semiliquid food mixture entering small intestine.

Small Intestine

20 feet long; completes digestion and absorbs nutrients.

Liver Functions

Produces bile, stores glycogen, processes proteins.

Pancreas Functions

Secretes pancreatic juices; produces insulin.

Large Intestine

Absorbs water and electrolytes; forms feces.

Feces Formation

Undigested material processed in large intestine.

Ileocecal Valve

Regulates passage from small to large intestine.

Rectal Sphincters

Control elimination of fecal material.

Internal anal sphincter

Involuntary muscle controlling anal opening.

External anal sphincter

Voluntary muscle controlling anal opening.

Colon

Absorbs excess liquid from chyme.

Feces

Waste formed for elimination through rectum.

Rectum

6-8 inches long; collects feces.

Anal canal

Passageway from rectum to anus.

Anus

Opening of anal canal to outside.

Oral phase

Voluntary phase of swallowing process.

Bolus

Food mixed with saliva, ready for swallowing.

Pharyngeal phase

Involuntary phase pushing bolus to pharynx.

Epiglottis

Prevents food from entering trachea.

Esophageal phase

Involuntary phase moving bolus to stomach.

Lower esophageal sphincter (LES)

Regulates entry of bolus into stomach.

Small intestine

Primary site for nutrient absorption.

Duodenum

First small intestine section; absorbs iron.

Jejunum

Middle section; major nutrient absorption site.

Ileum

Last section; absorbs vitamin B12 and bile salts.

Lacteals

Lymph vessels absorbing fats in small intestine.

Water absorption

Mainly occurs in small and large intestines.

Nutrient absorption

Occurs through intestinal villi into bloodstream.

Salivary glands

Produce saliva for digestion; includes parotid, submandibular, sublingual.

Absorption Function

Nutrient uptake begins in the jejunum.

Villi

Microscopic structures aiding nutrient absorption.

Nutrient Transport

Movement of absorbed nutrients into the bloodstream.

Lacteal

Lymphatic capillary in each villus for fat absorption.

Portal Vein

Carries absorbed nutrients to the liver.

Carbohydrates

Absorbed as sugars in the villi.

Fats

Absorbed into lacteals before entering circulation.

Minerals

Absorbed through villi cells as needed.

Water Absorption

Occurs through external cells of the villi.

Colonoscopy

Examines the large intestine using a fiber-optic scope.

Barium Swallow

Radiopaque liquid used to visualize the esophagus.

Upper GI Series

Fluoroscopy evaluates esophagus, stomach, small intestine.

Lower GI Series

Barium enema visualizes the large intestine.

Gastroscopy

Examines esophagus, stomach, duodenum with a scope.

Nuclear Medicine Studies

Uses radioactive materials to scan digestive organs.

Occult Blood Test

Detects hidden blood in stool for GI issues.

Proctoscopy

Examines lower rectum and anal canal.

Sigmoidoscopy

Views sigmoid colon for inflammation and tumors.

Anorectal Abscess

Localized infection near the anus causing pain.

Fistula

Abnormal connection formed due to abscess drainage.

Surgical Incision and Drainage

Treatment for anorectal abscess.

Appendicitis

Acute inflammation of the appendix, often due to blockage.

Surgical incision and drainage

Procedure to relieve abscess or fluid accumulation.

Signs of Appendicitis

Abdominal pain, nausea, vomiting, slight fever.

Cirrhosis

Chronic liver disease causing cell destruction and dysfunction.

Signs of Cirrhosis

Jaundice, bleeding, edema, mental confusion, ascites.

Colitis

Inflammation of the colon, acute or chronic.

Colorectal Cancer

Cancer of the colon or rectum, third most common.

Signs of Colorectal Cancer

Black stools, anemia, abdominal pain, rectal bleeding.

Colostomy

Artificial opening of the colon through the abdominal wall.

Constipation

Sluggish bowel action resulting in hard, infrequent stools.

Causes of Constipation

Poor diet, fluid intake, lack of exercise.

Constipation in Infants

Caused by early solid foods, formula switch, toilet training.

Symptoms of Infant Constipation

Fussiness, colic, excessive gas, infrequent stools.

Crohn's Disease

Inflammation affecting any part of the GI tract.

Symptoms of Crohn's Disease

Pain, cramping, diarrhea, weight loss, weakness.

Etiology of Diarrhea

Infections, poor diet, toxic substances, nervousness.

Diverticulitis

Presence of bulging pouches in the GI tract wall.