The Digestive System

These flashcards cover key terms and definitions from the digestive system lecture, helping students to study critical components, processes, and functions within the human body.

Gastrointestinal Tract

A continuous tube lined with a mucous membrane that includes the oral cavity, esophagus, stomach, small intestine, large intestine, and anus.

Accessory Digestive Organs

Organs that assist in the breakdown of food, including salivary glands, liver, gallbladder, and pancreas.

Mucosa

The innermost layer of the gastrointestinal tract, consisting of epithelium, lamina propria, and muscularis mucosae.

Submucosa

The layer of connective tissue that lies beneath the mucosa, containing blood vessels, lymphatics, and nerves.

Muscularis Externa

The layer of smooth muscle that is responsible for peristalsis and segmentation in the gastrointestinal tract.

Adventitia/Serosa

The outermost layer of the gastrointestinal tract; adventitia is composed of connective tissue, while serosa is a smooth membrane that covers organs in the abdominal cavity.

Peristalsis

The coordinated muscle contraction that moves food through the digestive tract.

Chyme

The semi-liquid mixture of food and digestive juices found in the stomach.

Gastric Pits

Openings in the stomach mucosa that lead to gastric glands, responsible for secreting digestive substances.

Salivary Amylase

An enzyme in saliva that initiates the chemical breakdown of starch.

Rugae

Folds in the stomach lining that allow the stomach to expand when filled with food.

Bile

A digestive fluid produced by the liver that emulsifies fats in the small intestine.

Cholecystokinin (CCK)

A hormone released by the small intestine that stimulates gallbladder contraction and bile release.

Absorption

The movement of substances from the lumen of the gastrointestinal tract into the cells.

Motility

The physical movement of food through the digestive tract, including mixing and propulsion.

Defecation Reflex

The involuntary and voluntary controls that result in the expulsion of feces from the body.

Acinar Cells

Cells in the pancreas that produce digestive enzymes for the small intestine.

Microvilli

Tiny projections on the surface of epithelial cells in the small intestine that increase surface area for absorption.

Barrett's Esophagus

A condition where the esophageal lining changes due to chronic acid reflux, increasing the risk of cancer.

Pepsinogen

The inactive precursor of pepsin, secreted by chief cells in the stomach.

Esophagus

A muscular tube connecting the throat (pharynx) with the stomach.

Stomach

A hollow organ that holds food while it is being mixed with stomach enzymes and acids.

Small Intestine

The part of the gastrointestinal tract between the stomach and large intestine, where most digestion and absorption occur.

Large Intestine

The part of the gastrointestinal tract that absorbs water from indigestible remnants of food and transmits the useless waste material from the body.

Feces

Waste material that is expelled from the digestive tract, typically consisting of undigested food, bacteria, and cells shed from the lining of the intestines.

Ascending Colon

The part of the large intestine that ascends on the right side of the abdomen.

Transverse Colon

The part of the large intestine that runs across the abdomen.

Descending Colon

The part of the large intestine that descends on the left side of the abdomen.

Sigmoid Colon

The S-shaped last part of the large intestine that leads into the rectum.

Rectum

The final section of the large intestine, terminating at the anus.

Anus

The opening at the end of the digestive tract through which feces leaves the body.

Liver

An organ that produces bile, processes nutrients from the digestive system, and detoxifies harmful substances.

Gallbladder

A small pouch that stores bile produced by the liver, releasing it into the small intestine to aid in digestion.

Pancreas

An organ that produces digestive enzymes and hormones, including insulin.

Insulin

A hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues.

Pepsin

An enzyme in the stomach that breaks down proteins into smaller peptides.

Hydrochloric Acid

A strong acid secreted by the stomach that helps digest food and kill microorganisms.

Intrinsic Factor

A protein produced by the stomach lining that is essential for the absorption of vitamin B12.

Probiotics

Live microorganisms that confer health benefits to the host, often found in fermented foods.

Prebiotics

Non-digestible food ingredients that promote the growth of beneficial microorganisms in the intestines.

Gastroesophageal Reflux Disease (GERD)

A chronic condition where stomach acid frequently flows back into the esophagus, causing irritation.

Ileum

The final part of the small intestine that connects to the large intestine.

Jejunum

The middle section of the small intestine where most digestion and absorption take place.

Duodenum

The first section of the small intestine where the majority of chemical digestion occurs.

Sphincters

Muscular valves that control the passage of food and liquids through the digestive tract.

Enterocytes

Specialized epithelial cells in the intestinal lining responsible for nutrient absorption.

Bicarbonate Secretion

A secretion from the pancreas that neutralizes stomach acid in the small intestine, creating an optimal pH for digestive enzymes.

Villi

Small, finger-like projections on the walls of the small intestine that increase surface area for absorption.

Amylase

An enzyme that catalyzes the breakdown of starch into sugars during digestion.

Protease

An enzyme that breaks down proteins into smaller peptides or amino acids during digestion.

Lipase

An enzyme responsible for breaking down fats into fatty acids and glycerol during digestion.

Gastrin

A hormone that stimulates the secretion of gastric acid by the stomach.