Digestive System: Glossary

Adventitia – The outermost connective tissue layer of an organ, such as the esophagusThe muscular tube that transports food from the pharynx to the stomach via peristalsis., which binds it to surrounding structures.

Anus – The terminal opening of the digestive tract through which fecesSolid waste material formed in the large intestine and expelled through the anus. are expelled.

Appendix – A small, finger-like pouch attached to the cecum, thought to play a role in immune function.

Bile – A digestive fluid produced by the liverA large organ that produces bile, detoxifies blood, and stores nutrients. and stored in the gallbladderA small organ beneath the liver that stores and releases bile into the small intestine.; it helps emulsify fats for digestion.

Bilirubin – A pigment derived from the breakdown of hemoglobinThe oxygen-carrying protein in red blood cells that gives blood its red color.; it gives bileA digestive fluid produced by the liver and stored in the gallbladder; it helps emulsify fats for di its yellow-green color and is excreted in bile.

Bolus – A rounded mass of food mixed with saliva that is ready for swallowing.

Brush Border – The microvilli-covered surface of intestinal epithelial cellsThe basic structural and functional units of life., increasing surface area for nutrient absorption.

Chief Cells – Gastric cells that secrete pepsinogen, an inactive enzyme that is converted into pepsin for protein digestion.

Cholesterol – A lipid molecule that is a key component of cell membranes and a precursor for bile acids and steroid hormones.

Chyme – A semi-fluid mixture of partially digested food and digestive juices that moves from the stomach into the small intestine.

Circular Folds (Plicae Circulares) – Permanent folds in the small intestine that increase surface area for nutrient absorption.

D Cells – Cells in the stomach and pancreasA gland that produces digestive enzymes and hormones like insulin and glucagon. that secrete somatostatinInhibits GH, insulin, and glucagon secretion., which inhibits gastric acidA substance that releases hydrogen ions (H⁺) in solution. secretionThe process of moving substances from the blood into the nephron tubule to be excreted in urine..

Duodenum – The first section A cut or slice of the body or an organ for study. of the small intestine where most digestion occurs; it receives chymeA semi-fluid mixture of partially digested food and digestive juices that moves from the stomach int, bile, and pancreatic enzymesProteins that speed up chemical reactions in the body..

Epiglottis – A flap of cartilageA flexible connective tissue found in joints, the ear, nose, and rib cage. Cartilage can be of three that covers the trachea during swallowing to prevent food from entering the airway.

Esophagus – The muscular tube that transports food from the pharynxThe muscular passageway connecting the mouth to the esophagus and larynx. to the stomach via peristalsis Rhythmic contractions of smooth muscle that move food through the digestive tract..

Feces – Solid waste material formed in the large intestine and expelled through the anusThe terminal opening of the digestive tract through which feces are expelled..

Fundus – The dome-shaped upper part of the stomach that stores undigested food and gases.

G Cells – Gastric cells that secrete gastrinA hormone that stimulates gastric acid secretion and motility., a hormone that stimulates acid production.

Gallbladder – A small organ beneath the liver that stores and releases bile into the small intestine.

Gastrin – A hormone that stimulates gastric acid secretion and motility.

Gastroesophageal – Relating to the stomach and esophagus, often used in reference to the gastroesophagealRelating to the stomach and esophagus, often used in reference to the gastroesophageal junction or r junction or reflux disease.

Haustrum – A pouch-like structure in the large intestine that helps move fecal material.

Hepatic Portal System – A network of veinsBlood vessels that return deoxygenated blood to the heart (except pulmonary veins, which carry oxyge that carry nutrient-rich blood from the digestive organs to the liver.

Hepatic Portal Vein – The main vein that transports blood from the digestive tract to the liver for processing.

Hepatocytes – Liver cells responsible for detoxification, metabolismThe sum of all chemical reactions in the body., and bile production.

Ileum – The last section of the small intestine, responsible for absorbing vitamin B12 and bile salts.

Intestinal Crypts (Crypts of Lieberkühn) – Glandular structures in the small intestine that produce digestive enzymes and new epithelial cells.

Jejunum – The middle section of the small intestine, primarily responsible for nutrient absorption.

Kupffer Cells – Specialized macrophages in the liver that help remove pathogens and old red blood cells.

Lacteal – A lymphatic vessel within a villus that absorbs dietary fats.

Liver – A large organ that produces bile, detoxifies blood, and stores nutrients.

Mastication – The process of chewing food to break it down into smaller pieces.

Mesentery – A fold of peritoneumThe membrane lining the abdominal cavity and organs. that supports and connects the intestines to the abdominal wall.

Mesocolons – Extensions of the peritoneum that anchor parts of the large intestine to the abdominal wall.

Microvilli – Tiny projections on the surface of epithelial cells that increase surface area for absorption.

Mouth – The opening of the digestive tract where food enters and masticationThe process of chewing food to break it down into smaller pieces. begins.

Mucosa – The innermost lining of the digestive tract that contains mucus-secreting cells for protection and absorption.

Muscularis Externa – A smooth muscle layer of the digestive tract responsible for peristalsis and segmentation.

Myenteric Plexus – A network of nerves within the muscularis externaA smooth muscle layer of the digestive tract responsible for peristalsis and segmentation. that controlsVariables that remain constant to ensure a fair test. digestive tract motility.

Omental Appendages – Small, fat-filled pouches attached to the colon, with an unclear function.

Omentum – A fold of peritoneum that contains fat and blood vessels, providing protection and support to abdominal organs.

Pancreas – A gland that produces digestive enzymes and hormones like insulin and glucagonIncreases blood sugar by promoting glycogen breakdown..

Parietal Cells – Cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factorA stomach-secreted protein necessary for vitamin B12 absorption, essential for vitamin B12 absorption.

Peristalsis – Rhythmic contractions of smooth muscle that move food through the digestive tract.

Peritoneum – A serous membrane that lines the abdominal cavityThe body cavity containing the stomach, intestines, liver, and other digestive organs. and covers the abdominal organs.

Pharynx – The muscular passageway connecting the mouthThe opening of the digestive tract where food enters and mastication begins. to the esophagus and larynxThe voice box; contains vocal cords and connects the pharynx to the trachea..

Pyloric – Relating to the pylorus, the region of the stomach that connects to the small intestine.

Rectum – The final section of the large intestine, where feces are stored before elimination.

Retroperitoneal – Referring to organs located behind the peritoneum, such as the kidneys and pancreas.

Rugae – Folds in the stomach lining that allow expansion when food enters.

Submucosal Plexus – A network of nerves in the submucosa that regulates glandular secretions and blood flow in the digestive tract.

Teniae Coli – Three bands of smooth muscle along the large intestine that help move feces.

Villi – Finger-like projections in the small intestine that increase surface area for absorption.