Digestive System Introduction and Overview

Comprehensive vocabulary flashcards covering anatomical divisions, wall histology, peritoneal membranes, motility types, and regulatory hormones of the human digestive system.

Duodenum

The first and shortest division of the small intestine, measuring less than $1\,\text{foot}$ in length.

Cecum

A blind-ending pouch on the right side of the abdominal cavity that forms the first division of the large intestine and has the appendix attached to it.

Sigmoid Colon

The S-shaped fifth division of the large intestine that travels medially and transitions into the rectum.

Mastication

The physical breakdown of food achieved by chewing in the oral cavity.

Mechanical Digestion

The physical breakdown of food into smaller particles—such as through chewing, mixing, and churning—without breaking chemical bonds.

Chemical Digestion

The process where enzymes break chemical bonds in food molecules, converting them into chemically different substances.

Amylase

An enzyme involved in chemical digestion that breaks down starch into maltose.

Macronutrients

The three bulk nutrients consumed in the diet: carbohydrates, lipids (fats), and proteins.

Nutrient Pool

The collected simple, absorbable units of macronutrients (monosaccharides, fatty acids, monoglycerides, and amino acids) utilized for ATP production and molecular synthesis.

Mucosa

The innermost layer of the digestive tract wall consisting of a lining epithelium, loose connective tissue, and a thin band of smooth muscle.

Lacteals

Lymphatic vessels located specifically within the submucosa of the small intestine that absorb dietary fats.

Muscularis

The layer of the digestive tract wall composed of smooth muscle organized into an inner circular layer and an outer longitudinal layer.

Serosa

The shiny, outermost layer of the digestive tract wall, which is formed by the visceral peritoneum.

Parietal Peritoneum

The outer serous membrane layer that lines the inner surface of the abdominal cavity walls.

Visceral Peritoneum

The deeper serous membrane layer that tightly adheres to and coats abdominal organs such as the stomach, liver, and intestines.

Retroperitoneal

A directional term describing organs situated behind the parietal peritoneum rather than suspended inside the peritoneal cavity, including the pancreas, kidneys, duodenum, and spleen.

Mesentery Proper

A specialized peritoneal structure responsible for holding the small intestine in place.

Greater Omentum

A fat-storing adipose structure derived from the peritoneum that hangs downward from the greater curvature of the stomach.

Lesser Omentum

An adipose tissue structure of the peritoneum attached to the lesser curvature of the stomach that serves in fat storage.

Bolus

A rounded ball of masticated food mixed with saliva that is swallowed and moved through the esophagus.

Deglutition

The physiological act or process of swallowing.

Peristalsis

Coordinated, wave-like smooth muscle contractions that propel food unidirectionally forward through the digestive tract.

Segmental Contractions

Localized, back-and-forth muscular contractions that retain chyme in a region of the small intestine to enhance mixing with enzymes and absorption.

Chyme

A pulpy, pasty mass of partially digested food mixed with gastric or intestinal secretions found within the stomach and small intestine.

Intrinsic Factor

A substance secreted by the stomach that is essential for the intestinal absorption of vitamin B12.

Gastrin

A digestive hormone secreted by the stomach and duodenum that targets the stomach to stimulate gastric motility and secretions.

Cholecystokinin (CCK)

A duodenal hormone that inhibits stomach emptying and motility, stimulates the gallbladder to release bile, and prompts the pancreas to release digestive enzymes.