2.2 The Digestive System

A comprehensive set of vocabulary flashcards based on the lecture notes for The Digestive System, covering organs, enzymes, and biological processes.

Digestion

The process by which the body breaks down food into smaller nutrient molecules through a series of organs forming the digestive tract.

Enzyme

A protein that speeds up chemical reactions in the body; specific enzymes take part in only one kind of chemical reaction.

Amylase

An enzyme found in saliva that breaks down starch into maltose, a disaccharide made of two glucose molecules.

Bolus

A ball of food mixed with saliva, rolled by the tongue and thrust into the back of the mouth for swallowing.

Epiglottis

A flap of tissue that flops down over the windpipe, or trachea, during swallowing to ensure food enters the esophagus.

Esophagus

A muscular tube, about $25\,\text{cm}$ long, that moves food from the mouth to the stomach using peristalsis.

Peristalsis

The progressive muscular movement of contracting and relaxing the walls of the esophagus or digestive tract to push food along.

Stomach

A J-shaped muscular organ in the abdominal cavity that stores food temporarily, mixes it with fluids, and begins protein digestion.

Pepsin

An enzyme in gastric juice that breaks down proteins into smaller polypeptides; it is activated by hydrochloric acid.

Pepsinogen

The inactive form of pepsin released inside the stomach to prevent the breakdown of the glands that contain it.

Chyme

The soupy, liquefied mixture of food and gastric juices formed in the stomach.

Duodenum

The upper part of the small intestine, which is $2.5\,\text{cm}$ wide and $7\,\text{m}$ long, where digestion continues with juices from the liver and pancreas.

Liver

An organ located in the upper abdomen that produces bile to aid in the digestion of fats.

Bile

A substance containing salts produced by the liver and stored in the gallbladder that breaks fat drops into smaller drops to increase surface area for enzymes.

Pancreas

An organ that aids digestion by supplying pancreatic juices containing lipase, trypsin, pancreatic amylase, and sodium bicarbonate.

Lipase

An enzyme in pancreatic juice that breaks down emulsified fats into glycerol and fatty acids.

Trypsin

An enzyme in pancreatic juice that breaks down proteins and polypeptides into amino acids.

Pancreatic amylase

An enzyme in pancreatic juice that transforms starch into maltose.

Sodium bicarbonate

A weak base in pancreatic juices that neutralizes acidic chyme and protects the duodenum from hydrochloric acid and pepsin.

Ileum

The lower part of the small intestine lined with a thin layer of cells that digest remaining molecules and perform absorption.

Peptic ulcer

A condition where the mucus lining the stomach or duodenum is abraded, often caused by Helicobacter pylori or anti-inflammatory drugs.

Absorption

The process allowing nutrients to pass from the digestive tract into the blood, occurring mainly through the walls of the small intestine.

Villi

Fingerlike projections on the ridges of the small intestine that increase surface area for faster nutrient absorption.

Microvilli

Microscopic cellular membrane protrusions on the cells lining the villi that further increase surface area.

Large intestine

A tube about $1.5\,\text{m}$ long and $6\,\text{cm}$ wide where water is absorbed, vitamins are produced by bacteria, and waste is prepared for elimination.

Rectum

A short tube at the end of the large intestine where waste material is stored before elimination.

Anus

A muscular opening at the end of the rectum through which waste material is eliminated.

Diarrhea

A condition characterized by loose, watery stools caused by increased fluid secretion, reduced absorption, or rapid passage of stool in the large intestine.