Digestive and Respiratory Systems – Key Terms

A vocabulary-style flashcard set covering key terms from the digestive and respiratory systems based on the given notes.

Digestive System

A complex network of organs that transforms food into essential nutrients and energy for growth, repair, and overall well-being.

Esophagus

A roughly 10-inch food tube that connects the throat to the stomach and uses peristalsis to move food downward.

Peristalsis

Rhythmic muscle contractions that propel food through the digestive tract.

Heartburn

Discomfort caused by stomach acid flowing back into the esophagus.

Stomach

A J-shaped organ that stores and mixes food with digestive juices; acidic environment helps break down proteins and fats and kills bacteria, forming chyme.

Chyme

The semi-liquid, soupy substance formed from partially digested food in the stomach.

Small Intestine

About 7 meters long; major site of nutrient absorption, lined with villi to increase surface area.

Villi

Millions of tiny finger-like projections on the small intestine lining that maximize nutrient uptake.

Enzymes

Proteins that digest carbohydrates, proteins, and fats in the small intestine.

Bile

Digestive fluid produced by the liver and stored in the gallbladder that aids fat digestion.

Liver

Organ that produces bile and detoxifies harmful substances.

Gallbladder

Stores and concentrates bile, releasing it into the small intestine as needed.

Pancreas

Produces digestive enzymes for all food types and helps regulate blood sugar.

Large Intestine

About 5 feet long; mainly absorbs water and vitamins from undigested material and forms solid stool.

Rectum

Temporary storage for stool before elimination.

Stool

Solid waste material formed from undigested material in the large intestine.

Fiber

Plant-based material that supports smooth digestion and bowel movement.

Hydration

Adequate water intake essential for digestion and overall function.

Nutrients

Substances absorbed from digested food that fuel body functions and growth.

Accessory Organs

Liver, gallbladder, and pancreas that assist digestion behind the scenes.

Stool Elimination

The process of removing solid waste from the body.

Digestion

The chemical and mechanical breakdown of food into usable nutrients.

Nasal Cavity

Filters, warms, and humidifies air; contains smell receptors.

Nose

Primary external entry point for air into the respiratory system.

Oral Cavity

Mouth; serves as an alternate entry point for air and is essential for speech and swallowing.

Pharynx

Throat; connects nasal cavity and mouth to the trachea; common pathway for air and food; contains the epiglottis.

Epiglottis

Flap-like structure that prevents food from entering the trachea during swallowing.

Larynx

Voice box; allows air to pass while preventing food from blocking the airway.

Trachea

Windpipe; hollow tube connecting the larynx to the bronchi, enabling airflow to and from the lungs.

Bronchi

Main airways into the lungs; branch from the trachea and are lined with cilia to move mucus out.

Cilia

Tiny hair-like structures in the bronchi that help move mucus and debris out of the lungs.

Bronchioles

Small branching air passages that connect bronchi to the alveoli.

Alveoli

Tiny air sacs where gas exchange occurs; oxygen enters the bloodstream and carbon dioxide is removed.

Alveolus

Singular form of alveoli.

Gas Exchange

Process of oxygen entering the bloodstream and carbon dioxide leaving the blood in the lungs.

External Respiration

Oxygen-rich air enters the alveoli and diffuses into the blood, binding to hemoglobin.

Internal Respiration

Oxygen is delivered to body tissues and carbon dioxide is removed from tissues and transported back to the lungs.

Hemoglobin

Protein in red blood cells that carries oxygen to tissues.

Oxygen

Vital gas required for cellular respiration.

Carbon Dioxide

Waste gas produced by metabolism and expelled by the lungs.

Diffusion

Movement of molecules from high to low concentration, such as O2 and CO2 across alveolar walls.

Diaphragm

A dome-shaped muscle that contracts to expand the chest cavity during inhalation and relaxes during exhalation.

Upper Respiratory Tract

Nose, nasal cavity, pharynx, and larynx—air passages above the trachea.

Lower Respiratory Tract

Trachea, bronchi, bronchioles, and lungs—air passages below the larynx.