BIO 202: The Digestive System

Flashcards for Anatomy and Physiology II Lecture on the Digestive System

Digestion

The organ system that processes food, extracts nutrients, and eliminates the residue.

Ingestion

Selective intake of food.

Digestion

Mechanical and chemical breakdown of food into usable form.

Absorption

Uptake of nutrient molecules into epithelial cells then into blood and lymph.

Compaction

Absorbing water and consolidating indigestible residue into feces.

Defecation

Elimination of feces.

Mechanical Digestion

Physical breakdown of food into smaller particles (e.g., chewing, churning).

Chemical Digestion

Series of hydrolysis reactions breaking macromolecules into monomers, aided by enzymes.

Digestive Tract (Alimentary Canal)

30-foot long muscular tube from mouth to anus; includes mouth, pharynx, esophagus, stomach, small and large intestine.

Accessory Organs

Organs that aid digestion; includes teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Mucosa

Innermost layer of the digestive tract wall; includes epithelium, lamina propria, and muscularis mucosae.

Submucosa

Layer of the digestive tract wall surrounding the mucosa.

Muscularis Externa

Layer of the digestive tract wall with inner circular and outer longitudinal layers.

Serosa

Outermost layer of digestive tract wall; includes areolar tissue and mesothelium.

Mesenteries

Connective tissue sheets suspending stomach and intestines from abdominal wall; provide passage for blood vessels and nerves.

Parietal Peritoneum

Serous membrane lining the abdominal cavity wall.

Dorsal Mesentery

Translucent two-layered membrane extending to the digestive tract.

Lesser Omentum

Ventral mesentery from lesser curvature of stomach to the liver.

Greater Omentum

Hangs from greater curvature of stomach, covers small intestines like an apron.

Mesocolon

Extension of the mesentery that anchors the colon to the posterior abdominal wall.

Intraperitoneal

Organ enclosed by mesentery on both sides; considered within the peritoneal cavity (e.g., stomach, liver).

Retroperitoneal

Organ against posterior body wall, covered by peritoneum on anterior side only (e.g., duodenum, pancreas).

Myenteric Reflexes

Short reflexes in digestive tract; stretch or chemical stimulation acts through myenteric plexus.

Vagovagal Reflexes

Long reflexes in digestive tract; parasympathetic stimulation of digestive motility and secretion.

Gastrin

A hormone that stimulates distant parts of the digestive tract.

Secretin

A hormone that stimulates distant parts of the digestive tract.

Salivary Amylase

Enzyme that begins starch digestion in the mouth.

Lingual Lipase

Enzyme activated by stomach acid, digests fat after swallowing.

Lysozyme

Enzyme in saliva that kills bacteria.

Deglutition

The act of swallowing.

Pepsinogen

A zymogen secreted by the chief cells.

Pepsin

An active enzyme secreted by the chief cells, digesting dietary proteins into shorter peptide chains.

Gastric Lipase

Produced by chief cells, plays a minor role in digesting dietary fats.

Intrinsic Factor

Glycoprotein secreted by parietal cells, essential for vitamin B12 absorption.

Chyme

Soupy or pasty mixture of semi-digested food in the stomach.

Duodenum

First 25 cm of small intestine, begins at the pyloric valve, receives stomach contents, pancreatic juice, and bile.

Jejunum

First 40% of small intestine beyond duodenum, most digestion and nutrient absorption occurs here.

Ileum

Last 60% of the postduodenal small intestine, thinner, less muscular, less vascular, and paler pink color.

Segmentation

Stationary ringlike constrictions appear in several places along the intestine.

Peristalsis

Gradual movement of contents towards colon. Begins after absorption occurs

Lipases

Fat digesting enzymes.

Bile

A yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids

Chemiosmosis

Oxidative Phosphorylation

Aerobic respiration

The final electron acceptor in the electron transport chain is molecular oxygen (O2).

Calories

A measure of the energy stored in your food and a measure of the energy you expend in daily activities

Obesity

An inappropriate ratio of weight to height

Catabolism

Degradative reactions that release energy (e.g., burning sugar).

Anabolism

Building complex molecules that consume energy (e.g., protein synthesis).

Trypsinogen

A pancreatic zymogen secreted into intestinal lumen and converted to trypsin by enterokinase.

Procarboxypeptidase

A pancreatic zymogen converted to carboxypeptidase by trypsin.