Digestive System Overview

Vocabulary flashcards covering key structures, processes, hormones, and cells of the digestive system for exam review.

Alimentary Canal (GI Tract)

Continuous 25-ft tube from mouth to anus through which food passes; includes pharynx, esophagus, stomach, small & large intestines.

Mucosa

Innermost GI tract layer that secretes protective mucus.

Submucosa

GI layer housing blood and lymphatic vessels plus nerves.

Muscularis

GI layer of inner circular & outer longitudinal smooth muscle responsible for motility.

Serosa

Protective outer covering that anchors digestive organs.

Peritoneum

Serous membrane that suspends and supports abdominal digestive organs.

Ingestion

Intake of food through the mouth.

Propulsion

Movement of food via swallowing and peristalsis.

Mechanical Digestion

Physical breakdown of food by chewing and stomach churning.

Chemical Digestion

Enzymatic breakdown of food into absorbable molecules.

Absorption

Transport of digested nutrients into blood or lymph, mainly in small intestine.

Defecation

Elimination of indigestible solids (feces).

Peristalsis

Involuntary rhythmic waves of contraction that propel food along the GI tract.

Gastrin

Stomach hormone that stimulates acid secretion when food is present.

Cholecystokinin (CCK)

Duodenal hormone that releases bile and pancreatic enzymes after fatty or protein-rich meals.

Lips

External boundaries of oral cavity; cover orbicularis oris muscle.

Palate

Roof of mouth; hard and soft portions with uvula to block nasal passage during swallowing.

Fungiform Papillae

Mushroom-shaped tongue projections containing taste buds.

Filiform Papillae

Thread-like tongue projections providing touch sensation.

Lingual Lipase

Enzyme from lingual glands that begins fat digestion in the stomach.

Submandibular Gland

Salivary gland beneath mandible producing mixed saliva via submandibular duct.

Sublingual Gland

Small salivary gland under tongue with multiple ducts.

Parotid Gland

Largest salivary gland anterior to ear; secretes enzyme-rich watery saliva via parotid duct.

Salivary Amylase

Enzyme in saliva that begins carbohydrate digestion.

Immunoglobulin A (IgA)

Antibody in saliva providing antimicrobial defense.

Lysozyme

Antimicrobial enzyme in saliva that lyses bacterial cell walls.

Crown (Tooth)

Visible portion of a tooth above the gum line.

Root (Tooth)

Portion of a tooth embedded in alveolar bone.

Pulp Cavity

Central tooth chamber containing blood vessels and nerves.

Deglutition

Process of swallowing; involves oral, pharyngeal, and esophageal phases.

Upper Esophageal Sphincter

Skeletal muscle valve between pharynx and esophagus controlling food entry.

Lower Esophageal Sphincter

Smooth muscle valve at stomach entrance preventing acid backflow.

GERD

Gastroesophageal reflux disease caused by weak lower esophageal sphincter allowing acid reflux.

Stomach

Muscular sac that stores food, mixes it into chyme, and begins protein digestion.

Chyme

Thick acidic semifluid mixture of food and gastric juice leaving the stomach.

Cardia

Stomach region adjoining the esophagus.

Fundus

Dome-shaped upper stomach portion.

Pylorus

Stomach region connecting to duodenum and controlled by pyloric sphincter.

Rugae

Folds in stomach mucosa allowing expansion.

Parietal Cells

Gastric gland cells producing hydrochloric acid and intrinsic factor.

Intrinsic Factor

Parietal-cell glycoprotein required for vitamin B12 absorption.

Chief Cells

Gastric gland cells secreting pepsinogen, an inactive protein-digesting enzyme.

Pepsinogen

Inactive precursor activated to pepsin for protein digestion in acidic stomach.

Enteroendocrine Cells

Gastric cells releasing hormones such as gastrin.

Small Intestine

10-ft organ (duodenum, jejunum, ileum) where most digestion and absorption occur.

Duodenum

First 10 inches of small intestine receiving chyme, bile, and pancreatic juice.

Jejunum

Middle small-intestine segment specialized for nutrient absorption.

Ileum

Terminal small-intestine segment ending at ileocecal valve.

Circular Folds

Permanent mucosal ridges that slow chyme and increase surface area.

Villi

Finger-like mucosal projections housing capillaries and lacteals for absorption.

Microvilli

Brush-border membrane extensions containing digestive enzymes.

Segmentation

Back-and-forth contractions mixing chyme with intestinal juices for absorption.

Large Intestine

Terminal GI tract region absorbing water, forming, and expelling feces.

Cecum

Blind pouch of large intestine receiving ileal contents; bears appendix.

Colon

Major large-intestine section (ascending, transverse, descending, sigmoid).

Bacterial Flora

700 intestinal microbial species synthesizing vitamins K, biotin, pantothenic acid.

Liver

Largest internal organ producing bile, processing nutrients, and detoxifying blood.

Hepatocyte

Liver cell performing metabolism, bile production, and detoxification.

Portal Triad

Corner of liver lobule containing bile duct, hepatic artery branch, and portal vein branch.

Bile

Liver secretion stored in gallbladder that emulsifies dietary fats.

Bilirubin

Greenish bile pigment from hemoglobin breakdown.

Gallbladder

Muscular sac beneath liver that stores and concentrates bile.

Pancreas

Mixed gland producing digestive enzymes (exocrine) and hormones (endocrine).

Acini Cells

Pancreatic exocrine cells secreting enzyme-rich pancreatic juice.

Islets of Langerhans

Pancreatic endocrine clusters releasing insulin, glucagon, and other hormones.

Secretin

Duodenal hormone stimulating bicarbonate-rich pancreatic juice.

Hepatic Portal Vein

Vessel carrying nutrient-rich blood from GI tract to liver.

Hepatic Artery

Blood vessel delivering oxygenated blood to the liver.

Hepatic Sinusoid

Leaky capillary channel within liver lobules where blood mixes and is processed.