Chapter 26: Digestion

Vocabulary flashcards for the digestive system, covering organs, functions, and processes.

Gastrointestinal (GI) Tract

Muscular tube from the oral cavity to the anus, including the pharynx, esophagus, stomach, and small and large intestines; also called the alimentary canal.

Ingestion

The process of taking materials into the digestive tract via the mouth.

Motility

Crushing and moving food along the GI tract.

Secretion

Release of water, acids, enzymes, buffers, and salts by the digestive epithelium and accessory glands.

Digestion

Chemical breakdown of food into small fragments for absorption by the digestive epithelium.

Absorption

Movement of nutrients and water across the digestive epithelium into the interstitial fluid.

Elimination

Defecation, or removal of waste from the body.

Peristalsis

Wave of contraction that propels a bolus along the digestive tract.

Oral Cavity

The mouth; functions include sensory analysis, mechanical processing, lubrication, and limited chemical digestion.

Lingual Lipase

Enzyme secreted by the tongue for some lipid digestion in the oral cavity.

Salivary Amylase

Enzyme secreted by serous cells in salivary glands that aids in chemical digestion of carbohydrates.

Dentin

Mineralized matrix similar to bone that forms the bulk of a tooth; does not contain cells.

Enamel

Hard, outermost layer covering the dentin of the crown of a tooth.

Incisors

Blades; teeth used for clipping or cutting.

Cuspids (Canines)

Conical; pointed teeth used for shearing or tearing.

Bicuspids (Premolars)

Flattened teeth with prominent ridges used for crushing, mashing, or grinding.

Molars

Large, flat teeth with ridges used for crushing or grinding.

Esophageal Hiatus

The opening in the diaphragm through which the esophagus passes.

Mucosa

The innermost layer of the GI tract, consisting of epithelium, lamina propria, and muscularis mucosae.

Submucosa

Layer of the GI Tract containing blood vessels, submucosal glands, and submucosal nerve plexus.

Muscularis

The muscle layer of the GI tract, typically with inner circular and outer longitudinal layers, and containing the myenteric nerve plexus.

Serosa

The outermost layer of the GI tract.

Enteroendocrine Cells

Cells that produce peptide hormones affecting digestion.

Mesenteries

Double sheets of peritoneal membrane that stabilize the positions of organs, prevent intestines from becoming entangled, and provide an access route for vessels and nerves.

Rugae

Gastric folds in the stomach.

Pyloric Sphincter

Smooth muscle to regulate chyme release into the duodenum.

Gastric Pits

Shallow depressions on the gastric surface of the stomach.

Gastric Glands

Connect to gastric pits in the fundus and body of the stomach.

Parietal Cell

Secretes intrinsic factor and hydrochloric acid.

Chief Cell

Secretes pepsinogen and gastric lipase.

Pepsin

Enzyme in the stomach that begins the preliminary digestion of proteins at an acidic pH.

Plicae Circulares

Permanent Circular folds within the small intestine.

Intestinal Villi

Fingerlike projections of mucosa in the small intestine.

Microvilli

Folded, fingerlike projections of plasma membrane on apical surface of columnar epithelial cells in the small intestine.

Peyer’s Patches

Abundant lymphoid tissue in the ileum.

Pancreatic Acini

Secrete pancreatic juice.

Pancreatic Alpha-Amylase

Enzyme that breaks down polysaccharides.

Pancreatic Lipase

Enzyme that breaks down triglycerides.

Proteolytic Enzymes

Proteases and peptidases; break down proteins or polypeptides.

Liver Lobules

Basic functional units of the liver.

Hepatocytes

Liver cells arranged like spokes.

Kupffer Cells

Phagocytic cells in the liver.

Emulsification

Process by which bile salts break down lipids, increasing surface area exposed to enzymatic attack.

Enterogastric reflex

A neural reflex that inhibits gastric motility and secretion when the duodenum is distended or contains irritating substances.

Gastroileal Reflex

Increased gastric activity causes increased motility in the ileum and movement of chyme through the ileocecal valve.

Haustra

Pouches or sacculations in the wall of the colon.

Taeniae Coli

Longitudinal bands of smooth muscle in the colon.

Anal Columns

Longitudinal folds in the anal canal

Mass Movements

Powerful peristaltic contractions in the large intestine that move material from the transverse colon to the anus.