Chapter 24 Lecture Notes Flashcards

Flashcards of vocabulary terms and definitions from the lecture notes.

Gastroenterology

Medical profession that studies the structures, functions, and disorders of the upper digestive tract.

Proctology

Medical profession that studies the structures, functions, and disorders of the lower digestive tract.

Gastrointestinal Tract (GI Tract)

The tube open at both ends for the transit of food during processing.

Ingestion

Taking food into the mouth (eating).

Secretion

The release of water, acid, buffers, and enzymes into the lumen of the GI tract by cells within its walls and accessory organs.

Mechanical Digestion

Movements of the GI tract that aid chemical digestion.

Chemical Digestion

A series of catabolic (hydrolysis) reactions that break down large food molecules into smaller molecules.

Absorption

The passage of end products of digestion from the GI tract into blood or lymph.

Defecation

Emptying of the rectum, eliminating indigestible substances from the GI tract.

Mucosa

The innermost layer of the gastrointestinal tract, consisting of an epithelium, lamina propria, and muscularis mucosa.

Submucosa

A layer of aerolar connective tissue that is highly vascular and contains the submucosal plexus.

Muscularis

Layer of the GI tract responsible for voluntary swallowing and peristalsis.

Serosa

The superficial layer of portions of the GI tract suspended in the abdominopelvic cavity.

Enteric Nervous System (ENS)

The intrinsic set of nerves that governs the GI tract.

Submucosal Plexus (Plexus of Meissner)

Regulates movements of the mucosa, vasoconstriction, and innervates secretory cells of mucosal glands.

Myenteric Plexus (Plexus of Auerbach)

Controls GI tract motility.

Peritoneum

The largest serous membrane of the body.

Retroperitoneal

Located behind the peritoneum.

Mouth (Oral or Buccal Cavity)

Formed by the cheeks, hard and soft palate, lips, and tongue.

Salivary Glands

Glands that secrete saliva into the oral cavity.

Saliva

Lubricates and dissolves food and starts the chemical digestion of carbohydrates.

Tongue

Forms the floor of the oral cavity.

Lingual Frenulum

The fold of mucous membrane that attaches to the midline of the undersurface of the tongue.

Teeth

Project into the mouth and are adapted for mechanical digestion.

Dentin

Calcified connective tissue that gives the tooth its basic shape and rigidity.

Enamel

The hardest substance in the body, covering the dentin of the crown.

Cementum

A bone-like substance covering the dentin of the root.

Mastication

Chewing.

Bolus

A soft, rounded mass of food that is easily swallowed.

Salivary Amylase

Converts polysaccharides (starches) to disaccharides (maltose).

Pharynx

A funnel-shaped tube that extends from the internal nares to the esophagus posteriorly and the larynx anteriorly.

Esophagus

A collapsible, muscular tube that lies behind the trachea and connects the pharynx to the stomach.

Peristalsis

Propulsive contractions that push the bolus onward.

Deglutition

Swallowing.

Stomach

A J-shaped enlargement of the GI tract that begins at the bottom of the esophagus and ends at the pyloric sphincter.

Chyme

Liquid that results from the bolus mixing in the stomach.

Rugae

Folds in the mucosa of the stomach when it is empty.

Gastric Glands

Exocrine glands in the stomach.

Pepsin

An enzyme that is most effective in the very acidic environment (pH 2) of the stomach that converts proteins into peptides.

Gastric Lipase

Splits certain molecules in butterfat of milk into fatty acids and monoglycerides, and has a limited role in the adult stomach.

Pancreas

Connected to the duodenum via the pancreatic duct (duct of Wirsung) and accessory duct (duct of Santorini).

Pancreatic Juice

Fluid and digestive enzymes secreted by the acini.

Pancreatic Amylase

An enzyme that digests starch.

Liver

The heaviest gland in the body and the second largest organ in the body after the skin.

Gallbladder

Sac located in a depression on the posterior surface of the liver.

Bile

Emulsifies triglycerides.

Small Intestine

Extends from the pyloric sphincter to the ileocecal sphincter.

Circular Folds (Plicae Circularies)

Permanent ridges in the mucosa that enhance absorption by increasing surface area and causing chyme to spiral as it passes through the small intestine.

Villi

Fingerlike projections in the mucosa that increase the surface area of the epithelium available for absorption and digestion.

Lacteal

A lymphatic capillary for fat absorption.

Microvilli

Increase the surface area.

Intestinal Glands (Crypts of Lieberkuhn)

Cavities lined by glandular epithelium in the mucosa.

Segmentation

A localized contraction in areas containing food.

Lactose Intolerance

The inability to digest the sugar lactose found in milk and other dairy products.

Emulsification

Bile salts break the globules of triglycerides (fats) into droplets.

Chylomicrons

Protein-coated spherical masses.

Lipoproteins

Combination of lipid and protein.

Large Intestine (Colon)

Extends from the ileocecal sphincter to the anus.

Appendix

Hangs inferior to the cecum.

Taeniae Coli

Specialized portions of the longitudinal muscles that contract and gather the colon into a series of pouches called haustra.

Haustra

Pouches tha result from contractions from the taeniae coli.

Feces

Consist of water, inorganic salts, sloughed-off epithelial cells, bacteria, products of bacterial decomposition, and undigested parts of food.

Defecation

The elimination of feces from the rectum.

Diarrhea

Frequent defecation of liquid feces.

Constipation

Infrequent or difficult defecation.

Cephalic Phase

Stimulates gastric secretion and motility.

Gastric Phase

Can be regulated by neural and hormonal mechanisms.

Intestinal Phase

Begins when partially digested food enters the small intestine.

Dental Caries

Tooth decay, is started by acid-producing bacteria that reside in dental plaque, act on sugars, and demineralize tooth enamel and dentin with acid.

Peptic Ulcers

Crater-like lesions that develop in the mucous membrane of the GI tract in areas exposed to gastric juice.

Diverticula

Saclike outpouchings of the wall of the colon in places where the muscularis has become weak.

Hepatitis

An inflammation of the liver.

Anorexia Nervosa

A chronic disorder characterized by self-induced weight loss, body-image and other perceptual disturbances, and physiologic changes that result from nutritional depletion.