A&P 2 - Module 07, Digestive System

Digestive Tract

The pathway (series of organs) that food passes through when in the digestive system.

Gastrointestinal Tract

The pathway (series of organs) that food passes through when in the digestive system.

Alimentary Canal

The pathway (series of organs) that food passes through when in the digestive system.

Accessory Digestive Organs

Digestive organs that participate in digestive functions but food does not pass through.

Peritoneum

The serous membrane that surrounds many abdominopelvic organs.

Visceral Peritoneum

The inner layer of the abdominopelvic serous membrane.

Parietal Peritoneum

The outer layer of the abdominopelvic serous membrane.

Mucosa (layer)

The most superficial layer of the alimentary canal; a mucous membrane lining the alimentary canal.

Submucosa (layer)

A connective tissue layer located just deep to the mucosa layer.

Muscular Layer

A bilayer of smooth muscle located deep to the submucosa; performs peristalsis and segmentation in the alimentary canal.

Serosa

The deepest layer of the alimentary canal for abdominopelvic organs; also known as the visceral peritoneum.

Adventitia

The deepest layer of the alimentary canal for structures outside of the reach of the peritoneum (oral cavity, pharynx, thoracic esophagus, parts of the large intestine).

Peristalsis

Coordinated, rhythmic smooth muscle contractions in the gastrointestinal tract that help in the movement of food along the tract.

Segmentation

Seemingly random smooth muscle contractions in the gastrointestinal tract that help to mechanically digest and mix internal contents.

Ingestion

The placement of a substance into the body (i.e., oral cavity).

Digestion

The break down of a substance into smaller pieces or component parts.

Mechanical Digestion

The physical break down of a substance into smaller pieces.

Chemical Digestion

The chemical break down of the chemical bonds in a substance into component parts.

Absorption

The movement of nutrient subunits from the digestive tract into the blood or lymph vessels.

Defecation

The removal of undigested food material through the anal canal.

Oral Cavity

Mouth; the first region of the digestive tract where ingestion as well as mechanical and chemical digestion occur.

Labia

Lips; the anterior border of the oral cavity.

Cheek

The lateral border of the oral cavity.

Hard Palate

The bony, superior border of the oral cavity made from the maxillary and palatine bones.

Soft Palate

The tissue superior border of the oral cavity.

Tongue

A muscular accessory organ of the digestive tract that serves in mechanical digestion by moving food.

Uvula

A structure hanging from the superoposterior palate which keeps food from entering the pharynx before the body is ready (gag reflex).

Gingivae

The gums.

Gingivitis

Inflammation of the gums (gingivae) due to the build up of plaque, bacterial growth at the border of the tooth and gums.

Cleft Palate

A state of having non-fused maxillary bones, leaving a space between the oral and nasal cavities.

Tooth

An accessory digestive organ of the oral cavity which aids in mechanical digestion during mastication (chewing).

Crown (of a tooth)

The white portion of the tooth sticking out beyond the gingivae (gums).

Neck (of a tooth)

The transitional region of a tooth between the observable crown and the root buried in the gums.

Root (of a tooth)

The portion of a tooth that is hiding inside the gums and alveolus of the underlying bone.

Deciduous Teeth

Baby or milk teeth that are present in children but fall out prior to adulthood; 20 are present in normal children.

Permanent Teeth

Adult teeth that replace deciduous teeth during childhood and puberty; 32 are present in a normal adult.

Salivary Gland

An accessory digestive organ of the oral cavity which aids in chemical digestion through the production of saliva.

Saliva

The exocrine secretion of the salivary gland in the oral cavity; contains mostly water with salivary amylase, salivary lipase, and buffers.

Bolus

Food broken down and mixed with saliva.

Salivary Amylase

An enzyme that chemically breaks down complex carbohydrates; produced by the salivary glands in the oral cavity.

Salivary Lipase

An enzyme that chemically breaks down triglycerides; produced by the salivary glands in the oral cavity.

Mumps

A viral infection of the salivary glands.

Pharynx

The throat.

Nasopharynx

The superior region of the pharynx, directly posterior to the nasal cavity.

Oropharynx

The middle region of the pharynx, directly posterior to the oral cavity.

Laryngopharynx

The inferior region of the pharynx, near the larynx.

Esophagus

A tube connecting the pharynx and stomach.

Upper Esophageal Sphincter

A smooth muscle band located at the superior end of the esophagus which regulates movement of substances into the esophagus.

Lower Esophageal Sphincter

A smooth muscle band located at the inferior end of the esophagus which regulates movement of substances from the esophagus into the stomach.

Gastroesophageal Reflux Disease (GERD)

An abnormality in which the lower esophageal sphincter allows acidic stomach contents to move backwards into the esophagus. This event can cause the mucosa of the esophagus to degrade over time, causing symptoms of heartburn.

Stomach

An organ of the digestive system located after the esophagus and before the small intestine that creates an acidic environment for chemical digestion.

Rugae

Wrinkles located in the stomach that allow it to expand when filled.

Pyloric Sphincter

A band of smooth muscle around the inferior end of the stomach that regulates the movement of chyme from the stomach into the small intestine.

Chyme

Partially broken down food mixed with enzymes and acid.

Gastric Pit

The deep grooves in the stomach mucosa that house gastric glands.

Gastric Gland

The deep end of the gastric pit that produces exocrine secretions.

Parietal Cell

A cell of the stomach that produces hydrochloric acid to create an acidic environment.

Hydrochloric Acid (HCl)

A chemical with a low pH produced by parietal cells in gastric gland of the stomach.

Chief Cell

A cell of the stomach that produces pepsinogen.

Pepsinogen

An inactive enzyme produced by chief cells that is converted into pepsin by an acidic environment.

Pepsin

The active form of the proteolytic enzyme produced by chief cells in the stomach.

Peptic Ulcer

A condition when the alkaline (basic pH) mucus of the stomach or connected structures (esophagus, duodenum) is degraded and the acidic stomach contents damage the underlying mucosa.

Small Intestine

An organ of the digestive system located after the stomach and before the large intestine that provides mechanical and chemical digestion of all macronutrients and performs 90% of nutrient absorption.

Duodenum

The first portion of the small intestine, connected to the stomach, that receives exocrine secretions from the liver, gallbladder, and pancreas.

Jejunum

The middle portion of the small intestine.

Ileum

The last portion of the small intestine which is connected to the large intestine.

Circular Folds

Large folds in the mucosa of the digestive tract that are prominent in the small intestine and serve to increase surface area to increase nutrient absorption.

Villi

Small folds in the surface of the circular folds that serve to increase surface area to increase nutrient absorption.

Microvilli

Tiny extensions of the cell membrane of the epithelial cells in the mucosa of the small intestine that serve to increase surface area to increase nutrient absorption.

Ileocecal Valve

A band of smooth muscle around the connection between the small intestine (ileum) and large intestine (cecum) that regulates the movement of food into the large intestine.

Liver

An accessory digestive organ located in the superior abdominopelvic cavity that produces and secretes bile and filters nutrients, toxins, drugs, hormones, and other substances from the blood.

Gallbladder

An accessory digestive organ located on the inferior side of the liver that serves to store and concentrate bile before its secretion.

Hepatic Portal System

The blood vessel network that connects the small intestine to the liver which delivers newly absorbed nutrients directly to the liver for filtration before being circulated in the body.

Bile

An exocrine secretion produced by the liver, stored and concentrated in the gallbladder, and secreted by the liver and gallbladder into the small intestine. It functions to mechanically digest lipids by emulsification.

Emulsification

The process of mechanically breaking up large lipid-soluble substances into smaller pieces for greater surface area access by lipid enzymes.

Hepatitis

A condition of inflammation of the liver.

Cirrhosis

A condition characteristic of scar tissue formation in the liver which decreases liver function.

Gallstones

A condition where concentrated amounts of bile form mineralized stones in the gallbladder, reducing bile's release, and function of the gallbladder.

Acinar Cell

An exocrine cell of the pancreas which produces multiple enzymes and buffers, secreted into the pancreatic duct.

Pancreatic Duct

A tube that spans the length of the pancreas, collecting acinar cell secretions to be released into the duodenum.

Pancreatic Juice

A collection of enzymes, buffers, and water secreted by acinar cells in the pancreas.

Pancreatic Amylase

The carbohydrate enzyme produced and released by the acinar cells in the pancreas.

Pancreatic Lipase

The lipid enzyme produced and released by the acinar cells in the pancreas.

Trypsin

The protein enzyme produced and released by the acinar cells in the pancreas.

Lactose Intolerance

A condition where a person has a decreased amount or complete lack of the enzyme lactase for digesting lactose (milk product sugar). Ingestion of milk products cause digestive issues (pain, malabsorption, diarrhea, cramps, etc).

Large Intestine

An organ of the digestive system located after the small intestine that functions to reabsorb water and absorb less than 10% of nutrients before removing undigested nutrients by defecation.

Cecum

The initial pocket of the large intestine that chyme enters when exiting the small intestine; The appendix is attached to the inferior margin of the cecum.

Colon

The large, middle portion of the large intestine.

Rectum

The last portion of the large intestine where chyme is compacted to become feces.

Internal Anal Sphincter

The band of smooth muscle around the end of the rectum (end of anal canal) that relaxes when the tissue of the rectum stretches by being filled.

External Anal Sphincter

The band of skeletal muscle around the end of the rectum (end of anal canal) that is voluntarily controlled. This is the muscle that children learn to control during potty training.

Diarrhea

A condition caused by the decrease reabsorption of water in the large intestine.

Fecal Transplant

A procedure when donor feces are transplanted into a recipient in order to treat the microbiome, microbe colonies in the large intestine.