The Digestive System

gastrointestinal tract

a series of hollow structures that ingested material passes through (is propelled by peristalsis contractions)

GI organs

physically and chemically break down ingested material, absorbs nutrients and water, and pass the waste as stool

accessory organs

digestive system organs outside of the Gi tract that aid in the digestive process

progression of the alimentary canal

oral cavity → pharynx → esophagus → stomach → small intestine (duodenum → jejunum → ileum) → large intestine (cecum → ascending colon → transverse colon → descending colon → sigmoid colon → rectum → anal canal → anus)

integration of accessory digestion

• enzymes in saliva produced by salivary glands begin to break down ingested material in the oral cavity

• tongue and teeth contribute to mechanical digestion

bile and pancreatic digestive juice

enters GI tract at small intestine duodenum to aid in chemical breakdown of ingested material

the mesentery

anchors intestines to posterior abdominal wall, ensheathes branches of mesenteric arteries supplying the intestines

greater omentum

double-layered peritoneal fold that hangs down from the stomach like an apron, ensheathes blood vessels supplying the stomach

lesser omentum

double layered peritoneal fold connecting the stomach, liver, and duodenum

• free edge ensheathes the hepatic portal vein, hepatic artery, and bile duct (portal triad)

stomach

organ with three layers of muscle in its wall that mechanically digests food through churning and grinding

• intraperitoneal

• foregut structure

• upper left quadran

gastroesophageal junction/sphincter

a ring-shaped band of smooth muscle located at the junction where the esophagus connects to the stomach

cardia (stomach)

surrounds opening to the esophagus

fundus of stomach

dilates to accommodate food, fluid, and gas

body of stomach

accommodates gastric contents, major site of digestion

greater curvature of stomach

attachment site of greater omentum

pylorus

controls passage of digested matter into the duodenum

lesser curvature of stomach

attachment site of lesser omentum

gastric pits/glands

located within the mucosa and secrete HCl to denature proteins → activation of pepsinogen to pepsin → digestion of proteins

rugae

folds within the stomach mucosa

• aid in expansion (ie; when you eat a large meal)

• assist in mechanical digestion (ie; grip food)

• assist in chemical digestion by increasing surface area of gastric pits/glands

celiac trunk

branches are the arterial supply of stomach

portal vein

where venous drainage of the stomach flows into