Digestive System – Chapter 24 Vocabulary

A comprehensive set of vocabulary flashcards covering key structures, cells, functions, and processes of the digestive system as presented in Chapter 24 lecture notes.

Alimentary (Digestive) Tract

Continuous muscular tube running from mouth to anus through which food passes; also called the gastrointestinal tract.

Accessory Digestive Organs

Glands and structures (salivary glands, liver, gallbladder, pancreas) that release secretions into the alimentary canal but are not part of the tube itself.

Ingestion

Introduction of food and liquids into the oral cavity.

Mastication

Mechanical chewing that increases surface area of food for chemical digestion.

Peristalsis

Wavelike contractions of circular and longitudinal muscles that propel bolus or chyme through the digestive tract.

Segmental Contractions

Mixing movements in which alternating sections of intestine contract and relax, dispersing food and secretions.

Secretion (Digestive Function)

Release of mucus, water, bile, and enzymes that lubricate, liquefy, and chemically digest food.

Mucosa

Innermost layer of the digestive tract; epithelium plus lamina propria and muscularis mucosae.

Submucosal Plexus

Parasympathetic nerve network within the submucosa that regulates glandular secretions and local blood flow.

Muscularis

Two (or three) layers of smooth muscle—inner circular and outer longitudinal—that generate peristalsis and mixing; upper esophagus contains skeletal muscle.

Serosa (Visceral Peritoneum)

Outermost connective-tissue covering of intraperitoneal digestive organs.

Enteric Nervous System (ENS)

Local neural network (sensory, motor, interneurons) embedded in the digestive tract wall that coordinates reflexes independently of the CNS.

Gastrin

Hormone from stomach G-cells that stimulates gastric acid secretion and motility.

Secretin

Duodenal hormone that stimulates pancreatic bicarbonate and watery bile secretion to neutralize acid chyme.

Histamine (Digestive Paracrine)

Chemical released by enterochromaffin-like cells that increases gastric acid secretion.

Peritoneum

Serous membrane lining the abdominal cavity (parietal) and covering organs (visceral).

Mesenteries

Double layers of peritoneum that suspend organs and serve as pathways for vessels and nerves.

Retroperitoneal

Describes organs located behind the peritoneum and covered on only one surface (e.g., kidneys, pancreas, duodenum).

Oral Vestibule

Space between lips/cheeks and teeth–alveolar processes.

Fauces

Opening from oral cavity proper into the pharynx.

Hard Palate

Anterior bony portion of palate formed by maxilla and palatine bones.

Soft Palate

Posterior muscular portion of palate that closes nasopharynx during swallowing.

Uvula

Posterior projection of soft palate aiding in speech and swallowing.

Lingual Frenulum

Mucosal fold anchoring underside of tongue to the mouth floor.

Papillae (Tongue)

Projections on anterior tongue; some house taste buds and increase texture grip on food.

Deciduous (Primary) Teeth

First set of 20 “milk” teeth that erupt during childhood and are later replaced by permanent teeth.

Enamel

Hard, acellular, non-living outer covering of anatomic tooth crown providing protection.

Dentin

Living, calcified tissue forming bulk of tooth beneath enamel and cementum.

Periodontal Ligament

Collagenous fibers anchoring tooth root to alveolar bone socket.

Mastication Reflex

Medulla-controlled basic chewing pattern modulated by cerebral cortex for conscious control.

Parotid Gland

Largest salivary gland; serous secretion; duct opens near upper second molar.

Submandibular Gland

Mixed (mainly serous) salivary gland beneath mandible; ducts open beside lingual frenulum.

Sublingual Gland

Smallest salivary gland; primarily mucous; multiple ducts empty under tongue.

Salivary Amylase

Enzyme in saliva that initiates starch digestion to maltose and isomaltose.

Pharyngeal Constrictors

Skeletal muscles of pharynx that sequentially contract to propel bolus during swallowing.

Esophageal Sphincters

Upper (striated) and lower (smooth) muscular rings controlling food entry and preventing reflux.

Deglutition

Swallowing process consisting of voluntary, pharyngeal, and esophageal phases.

Fundus (Stomach)

Dome-shaped superior region of stomach, above gastroesophageal opening.

Gastric Pits

Microscopic invaginations in stomach mucosa that open into gastric glands.

Parietal Cells

Stomach gland cells releasing hydrochloric acid and intrinsic factor.

Chief Cells

Stomach cells that secrete pepsinogen, precursor of protein-digesting enzyme pepsin.

Enterochromaffin-Like (ECL) Cells

Gastric endocrine cells producing histamine to stimulate acid secretion.

Intrinsic Factor

Parietal-cell glycoprotein essential for intestinal absorption of vitamin B₁₂.

Chyme

Semi-fluid mixture of ingested food and gastric secretions entering duodenum.

Plicae Circulares

Permanent circular folds of small-intestinal mucosa/submucosa that amplify surface area.

Villi

Fingerlike mucosal projections of small intestine containing capillaries and lacteals.

Microvilli

Microscopic membrane folds on absorptive enterocytes forming the brush border.

Ileocecal Valve

Sphincter at junction of ileum and cecum that regulates flow of chyme into large intestine.

Kupffer Cells

Hepatic macrophages residing in liver sinusoids that phagocytize debris and aged cells.

Hepatopancreatic Ampulla

Union of common bile duct and pancreatic duct opening into duodenum (major papilla).

Gallbladder

Muscular sac that stores and concentrates bile, releasing it via the cystic duct.

Pancreatic Islets (Islets of Langerhans)

Endocrine cell clusters in pancreas secreting insulin, glucagon, and somatostatin.

Pancreatic Acini

Exocrine secretory units producing digestive enzymes released into pancreatic ducts.

Trypsin

Proteolytic enzyme from pancreas that continues protein digestion in small intestine.

Mass Movements

Powerful peristaltic contractions in large intestine that move feces toward rectum, often after meals.

Cecum

Blind pouch of large intestine below ileocecal valve; bears vermiform appendix.

Crypts (Intestinal Glands)

Straight tubular glands in colon mucosa rich in mucus-secreting goblet cells.

Gastrocolic Reflex

ENS-mediated reflex in which stomach filling triggers mass movements in colon.

Duodenocolic Reflex

Reflex where duodenal stretch stimulates colonic mass movements.