Digestive System

• Mouth components

  • Teeth
  • Tongue
  • Salivary glands
• Mouth function

  The process of digestion begins in the mouth. Chewing breaks the food into smaller pieces, and saliva mixes with the food to begin the chemical breakdown. The enzyme amylase in saliva starts breaking down carbohydrates.
• Esophagus components

  A muscular tube
• Esophagus function

  The esophagus transports food from the mouth to the stomach through a series of muscle contractions called peristalsis. At the end of the esophagus, a muscular ring called the lower esophageal sphincter relaxes to let food enter the stomach and then contracts to prevent stomach contents from coming back up.
• Stomach components

  • Fundus
  • Body
  • Antrum
  • Pylorus
  • Gastric glands
• Stomach function

  The stomach secretes acid and enzymes that digest food. The stomach muscles churn the food, mixing it with these digestive juices to create chyme (a semi-liquid mixture). The pyloric sphincter controls the flow of chyme from the stomach to the small intestine.
• Small intestine components

  • Duodenum
  • Jejunum
  • Ileum
• Small intestine function

  The small intestine continues the process of breaking down food with enzymes and bile. The majority of nutrient absorption occurs here. The duodenum receives chyme from the stomach, bile from the gallbladder, and pancreatic enzymes. The jejunum and ileum are mainly involved in nutrient absorption.
• Pancreas function


  The pancreas produces digestive enzymes and bicarbonate, which are released into the small intestine. These enzymes help digest proteins, fats, and carbohydrates. The pancreas also produces insulin and glucagon, which regulate blood sugar levels.
• Liver function

  The liver processes nutrients absorbed from the small intestine. It detoxifies chemicals, metabolizes drugs, and produces bile, which is stored in the gallbladder. Bile emulsifies fats, making them easier to digest.
• Gallbladder function


  The gallbladder stores and concentrates bile from the liver, releasing it into the small intestine to aid in fat digestion.
• Large intestine (colon) components

  • Cecum
  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon
• Large intestine (colon) function

  The large intestine absorbs water and salts from the material that has not been digested as food, and is mainly responsible for the formation of solid waste (feces). The colon houses a large number of bacteria that play a role in the fermentation of unabsorbed material.
• Rectum function


  The rectum stores feces until they are ready to be expelled. Stretch receptors in the rectum signal the need for a bowel movement.
• Anus components


  • Internal sphincter
  • External sphincter
• Anus function


  The anus controls the expulsion of feces from the body. The internal sphincter is involuntary, while the external sphincter is voluntary, allowing for control over bowel movements.
• Process of digestion

  1. Ingestion

  2. Propulsion

  3. Mechanical digestion

  4. Chemical digestion

  5. Absorption

  6. Defecation
• Mouth


  The beginning of the digestive tract. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form the body can absorb and use.
• Esophagus


  A muscular tube connecting the throat (pharynx) with the stomach. The esophagus delivers food to the stomach via a series of muscular contractions called peristalsis.
• Stomach


  A hollow organ that holds food while it is being mixed with stomach enzymes. These enzymes continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process.
• Small Intestine


  Made up of three segments—the duodenum, jejunum, and ileum—the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. The small intestine is where most of the nutrients from food are absorbed into the bloodstream.
• Pancreas


  Produces digestive enzymes and bicarbonate, which are released into the small intestine to aid in digestion. It also produces insulin and glucagon, which help regulate blood sugar levels.
• Liver


  Processes nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. The liver is the body's chemical "factory," performing over 500 functions including detoxifying harmful substances, making blood-clotting proteins, and storing vitamins and minerals.
• Gallbladder


  Stores and concentrates bile, and then releases it into the small intestine to help absorb and digest fats.
• Large Intestine (Colon)


  A 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is responsible for processing waste so that emptying the bowels is easy and convenient. The colon absorbs water and salts from the material that has not been digested as food, and is thus mainly responsible for the formation of solid waste (feces).
• Rectum


  An 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, let the person know that there is stool to be evacuated, and hold the stool until evacuation happens.
• Anus


  The last part of the digestive tract. It consists of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus can detect rectal contents. It lets the person know whether the contents are liquid, gas, or solid.