DIGESTION & THE HUMAN BODY – KEY VOCABULARY

Vocabulary flashcards covering key terms from the lecture on the organization of the body, processes of digestion, absorption, elimination, and digestive disorders.

Atom

The smallest unit of matter; bonds with other atoms to form molecules.

Molecule

A group of atoms bonded in a specific configuration, e.g., H₂O; building blocks of cells.

Cell

The smallest unit of life, constructed from molecules produced by digestion.

Tissue

A group of cells acting together to perform a common function, such as muscle or nerve tissue.

Organ

A sophisticated structure composed of multiple tissues that performs a specific function (e.g., stomach, heart).

Organ System

Group of organs working together for a particular function, such as the gastrointestinal system.

Organism

The complete living being formed by the integration of multiple organ systems.

Cell Membrane

Semipermeable outer layer of a cell that defines boundaries and regulates passage of materials.

Cytoplasm

The liquid interior of a cell enclosed by the membrane and containing organelles.

Organelle

Tiny cellular structure that performs specialized functions within the cell.

Semipermeable

Property of the cell membrane allowing selective movement of substances into and out of the cell.

Appetite

Psychological desire to eat certain foods, causing cravings even without hunger.

Hunger

Physiological sensation that prompts eating; detected by the hypothalamus.

Satiety

Feeling of fullness that suppresses further eating.

Hypothalamus

Brain region that receives signals about stomach fullness, blood glucose, and hormones to regulate hunger.

Hormone

Chemical messenger made in glands, traveling through blood to target organs; can stimulate intake or satiety.

Protein (Satiety)

Macronutrient with the highest satiety value, keeping us full longest.

Carbohydrate (Satiety)

Macronutrient with lower satiety value than fats and proteins.

Fat (Satiety)

Macronutrient with higher satiety value than carbohydrates but lower than proteins.

Bulky Food

Food high in volume (often fiber‐rich) that promotes satiety.

Gastrointestinal (GI) Tract

Long tube of organs where digestion, absorption, and elimination occur.

Sphincter

Circular muscle controlling passage of material from one GI organ to the next.

Digestion

Process of mechanically and chemically breaking large food molecules into smaller absorbable units.

Absorption

Movement of digested nutrients across intestinal cell membranes into blood or lymph.

Elimination

Excretion of undigested food components and waste from the body.

Peristalsis

Rhythmic muscular contractions that move food through the GI tract.

Epiglottis

Flap that covers the trachea during swallowing to prevent choking.

Upper Esophageal Sphincter

Muscle ring controlling entry of food from pharynx into esophagus.

Gastroesophageal Sphincter

Muscle separating esophagus from stomach; prevents reflux of stomach contents.

Stomach

Organ where extensive mechanical mixing with gastric juice forms chyme and protein/fat digestion begins.

Gastric Juice

Stomach secretion containing HCl, pepsin, gastric lipase, and mucus.

Hydrochloric Acid (HCl)

Strong acid in gastric juice that denatures proteins and activates pepsin.

Pepsin

Protein‐digesting enzyme activated by HCl in the stomach.

Gastric Lipase

Enzyme in gastric juice that initiates fat digestion.

Chyme

Semi‐solid mixture of partially digested food and gastric secretions leaving the stomach.

Pyloric Sphincter

Muscle controlling the release of chyme from stomach to small intestine.

Small Intestine

Primary site of chemical digestion (via pancreatic enzymes & bile) and nutrient absorption.

Liver

Accessory organ that produces bile to emulsify fats.

Bile

Liver secretion stored in gallbladder; emulsifies fats for digestion.

Gallbladder

Organ that stores and releases bile into the small intestine.

Pancreas

Accessory organ producing digestive enzymes and hormones that regulate metabolism.

Villus (plural Villi)

Folded projection of the small-intestinal lining that absorbs nutrients.

Microvillus

Microscopic extension on villi forming the brush border, greatly increasing surface area.

Brush Border

Dense array of microvilli on intestinal cells that maximizes absorption surface.

Lacteal

Lymphatic vessel inside a villus that absorbs lipids and fat‐soluble nutrients.

Ileocecal Valve

Sphincter controlling passage of material from small intestine to large intestine.

Large Intestine

Organ where water absorption, bacterial digestion of remnants, and feces formation occur.

Cecum

First pouch-like region of the large intestine.

Colon (Ascending, Transverse, Descending, Sigmoid)

Major segments of the large intestine that store and move fecal matter toward rectum.

Rectum

Final section of the large intestine where feces are stored before elimination.

Anus

Opening through which feces leave the body.

Enteric Nerves

Network of nerves that serve the GI tract, coordinating motility and secretions.

Heartburn

Burning sensation caused by HCl reflux into the esophagus.

Gastroesophageal Reflux Disease (GERD)

Chronic, painful heartburn due to persistent acid reflux.

Peptic Ulcer

Eroded region of the stomach or duodenal lining caused by HCl/pepsin; often linked to H. pylori.

Helicobacter pylori

Bacterium that contributes to gastric and duodenal ulcer formation.

Food Intolerance

GI symptoms (gas, pain, diarrhea) triggered by specific foods; e.g., lactose intolerance.

Lactose Intolerance

Inability to digest lactose leading to GI discomfort; example of food intolerance.

Food Allergy

Immune response to a particular food that can be mild or severe.

Celiac Disease

Genetic immune reaction to gluten that damages small-intestinal villi and impairs nutrient absorption.

Diarrhea

Frequent loose stools caused by infections, intolerances, stress, etc.; risk of dehydration.

Constipation

Infrequent or difficult bowel movements; may result from diet, medication, or routine changes.

Irritable Bowel Syndrome (IBS)

Condition disrupting normal colon function, causing cramps, bloating, and alternating diarrhea or constipation; more common in women.