Chapter 19: The Digestive System Lecture Flashcards

This set of vocabulary flashcards covers key terms, organ functions, enzymes, hormones, and disorders of the human digestive system as presented in Chapter 19.

Digestion

The mechanical and chemical breakdown of food into smaller components that can be absorbed.

Absorption

The process by which digested materials are taken from the digestive tract into the circulation.

Elimination

The process of removing solid waste products from the body.

Peritoneum

A serous membrane consisting of a parietal layer that lines the body cavity and a visceral layer that covers the organs.

Mesentery

A subdivision of the peritoneum that attaches the intestine to the posterior abdominal wall.

Greater Omentum

A subdivision of the peritoneum that hangs like an apron over the front of the intestines.

Mucosa

The innermost layer of the digestive tract wall, consisting of epithelium, connective tissue, and smooth muscle.

Submucosa

The layer of connective tissue beneath the mucosa containing blood vessels, lymph vessels, and nerves.

Muscularis

The layer of the digestive tract wall composed of circular and longitudinal layers of smooth muscle.

Serosa

The outermost layer of the digestive tract wall, composed of areolar connective tissue and epithelium.

Peristalsis

A wave of circular muscle contraction that moves food through the gastrointestinal tract from the mouth toward the anus.

Segmentation

A type of motility in the digestive tract involving localized circular muscle contractions that mix food.

Mastication

The act of chewing food, which occurs in the oral cavity.

Deglutition

The process of swallowing a prepared bolus of food.

Salivary Amylase

An enzyme in the mouth that initiates the digestion of starch.

Rugae

Folds on the inner surface of the stomach that allow the organ to expand when filled with food.

Pepsin

An active enzyme in the stomach that initiates the digestion of proteins.

Chyme

The semi-liquid mixture of ingested food, gastric juice, and mucus formed in the stomach.

Lower Esophageal Sphincter (LES)

The ring of muscle that controls the passage of food from the esophagus into the stomach.

Pyloric Sphincter

The valve that regulates the flow of food from the stomach into the duodenum.

Villi

Tiny, finger-like projections in the mucosa of the small intestine that increase surface area for absorption.

Lacteal

A lymphatic capillary located within an intestinal villus that absorbs fat.

Chyle

A milky-appearing mixture of lymph and absorbed fat that enters the lymphatic circulation.

Bile

A substance manufactured by the liver and stored in the gallbladder that emulsifies fat into smaller droplets.

Sodium Bicarbonate ($NaHCO_3$)

A substance synthesized by the pancreas that buffers acids as they enter the duodenum from the stomach.

Hydrolysis

The fundamental chemical reaction in the digestive process that uses water to break down nutrients.

Gastrin

A hormone stimulated by food in the mouth or stomach that increases gastric activity.

Secretin

A hormone stimulated by acid in the duodenum that triggers the secretion of bicarbonate and inhibits stomach activity.

Cholecystokinin (CCK)

A hormone stimulated by fat and protein in the duodenum that triggers pancreatic enzyme secretion and bile release.

Gastric-inhibitory peptide (GIP)

A hormone stimulated by glucose in the duodenum that inhibits stomach activity and stimulates insulin release.

Ghrelin

A hormone produced by an empty stomach that stimulates the hypothalamus to induce hunger sensations.

Leptin

A hormone produced by adipocytes that reduces hunger and increases activity for long-term body weight regulation.

Peritonitis

Inflammation of the peritoneum, often caused by a ruptured appendix, perforated ulcer, or penetrating wound.

Gastroesophageal Reflux Disease (GERD)

A condition resulting from the failing of the lower esophageal sphincter, leading to a backward flow of gastric acid into the esophagus.

Cirrhosis

A liver disease characterized by the replacement of active liver cells with inactive connective (scar) tissue.

Cholelithiasis

The formation of gallstones in the gallbladder.

Intussusception

An intestinal obstruction caused by one part of the intestine slipping into an adjacent part.

Volvulus

A form of intestinal obstruction caused by the twisting of the intestine.