The Digestive System By: Jama Willbanks, MS, NREMT-P
What is the digestive system's other name?
The Alimentary Canal • A long muscular tube that begins at the mouth and includes the oral cavity, pharynx, esophagus, stomach, small intestines, and large intestines.
The Alimentary Canal • The accessory organs include the salivary glands, tongue, teeth, liver, gallbladder, and pancreas.
The Mouth • Food is tasted, broken down by teeth, lubricated and partially digested by saliva.
The Teeth • Break down food by chewing and grinding (mastication).
The Tongue • Muscular organ. • Contains special receptors called taste buds. • Aids with chewing and swallowing food.
Hard Palate and Soft Palate • Hard palate: a bony structure that forms the roof of the mouth and separates the mouth from the nasal cavities. • Soft palate: behind hard palate, separates the mouth from the nasopharynx.
Salivary Glands • The parotid, sublingual, and submandibular glands produce a liquid called saliva. • Saliva lubricates the mouth during speech and chewing and moistens food so it can be swallowed easily.
Salivary Glands • Saliva contains an enzyme called salivary amylase. • Salivary amylase begins the chemical breakdown of carbohydrates or starches into sugars that can be taken into the body.
Bolus • After the food is chewed and mixed with saliva, it is called a bolus.
The Pharynx (Throat) • The pharynx is a tube that carries both air and food. • It carries the air to the trachea and food to the esophagus.
The Esophagus • The esophagus is the muscular tube posterior to the trachea that receives the bolus from the pharynx and carries it to the stomach. • The esophagus relies on peristalsis,a rhythmic, wavelike, involuntary movement of its muscles to move the food in a forward direction.
The Stomach • The stomach receives food from the esophagus. • The mucous membrane lining of the stomach contains folds called rugae that disappear as the stomach fills with food and expands.
Stomach • Food usually remains in the stomach for about one to four hours. • During this time, food is converted into a semifluid material called chyme by gastric juices produced by glands in the stomach.
The Small Intestine • When the food, in the form of chyme, leaves the stomach it enters the small intestine.
Purpose of the Small Intestine • Products of digestion are absorbed into the bloodstream for use by the body cells.
The Small Intestine • The small intestine is a coiled section of the alimentary canal about twenty feet long and one inch in diameter.
Villi • Walls of small intestine are lined with villi that contain blood capillaries and lacteals.
The Small Intestine • It is divided into three sections: duodenum, jejunum, and ileum.
Duodenum • The first nine to ten inches of the small intestine. • Bile from the gallbladder and liver and pancreatic juice from the pancreas enter this section through ducts or tubes.
Jejunum & Ileum • The jejunum is about eight inches long. • It forms the middle section of the small intestine. • The Ileum is the final 12 feet and connects with the large intestine at the cecum. • The ileocecal valve prevents backflow.
Large Intestine • Approximately 5 feet long. • Approximately 2 inch diameter.
Purpose of Large Intestine • Absorption of water and any remaining nutrients. • Storage of indigestible materials before they are eliminated. • Synthesis and absorption of some vitamins. • Transportation of waste.
Purpose of Large Intestine • Transportation of waste.
Sections of the Intestine • Cecum • Colon • Ascending • Transverse • Descending • Sigmoid Colon • Rectum: final six to eight inches.
Big Word of the Day Esophagogastroduodenoscopy esophagus gastric duodenum scope
We’ll just call it EGD • EGD: A diagnostic test used to aid in identifying abnormalities of the esophagus, stomach, and small intestines. • Abnormalities such as: esophagitis, inflammatory bowel disease, ulcers, tumors, gastritis, and polyps.
Accessory Organs • Liver • Gallbladder • Pancreas
Liver • Largest gland in the body. • Located under the diaphragm and in the upper right quadrant of the abdomen. • Secretes bile which is used to emulsify fats in the digestive tract. • Bile also makes fats water soluble (which is necessary for absorption).
Liver • Stores sugar in the form of glycogen. • Glycogen is converted to glucose and released into the bloodstream when needed. • Stores iron and certain vitamins. • Produces heparin which prevents clotting in the blood.
Liver • Produces blood proteins such as fibrinogen and prothrombin which aid in clotting of the blood. • Detoxifies substances such as alcohol and pesticides. • Destroys bacteria.
Gallbladder • Small, muscular sac located under the liver and attached to it by connective tissue. • Stores and concentrates bile which it receives from the liver. • Gallbladder contracts to push bile through the common bile duct and into the duodenum.
Pancreas • Located behind the stomach. • Produces pancreatic juices which contain enzymes to digest food. • Produces insulin which regulates the metabolism of glucose into energy.