3.2a Digestive system 2025

Lesson 3.2a

Digestive System

The system in the body responsible for breaking down food, absorbing nutrients, and removing waste.

Mechanical Digestion

The physical breakdown of food into smaller pieces, such as chewing and stomach churning.

Chemical Digestion

The breakdown of food molecules into smaller units by enzymes, transforming them into absorbable forms.

Enzymes

Proteins that speed up chemical reactions in the body, including those involved in digesting food.

Amylase

An enzyme that breaks down carbohydrates into simple sugars, found in saliva and the small intestine.

Hydrochloric Acid

An acid secreted in the stomach that creates an acidic environment ideal for enzyme activity.

Gastric Juice

A mixture of hydrochloric acid, enzymes, and mucus secreted by the stomach to aid in digestion.

Villi

Small, finger-like projections in the small intestine that increase surface area for nutrient absorption.

Peristalsis

The wave-like muscle contractions that move food along the digestive tract.

Pyloric Sphincter

A muscular valve that controls the release of chyme from the stomach into the duodenum.

Capillaries

Small blood vessels where the exchange of nutrients and waste takes place.

Lacteals

Lymphatic vessels in the small intestine that absorb fats and fat-soluble vitamins.

Chyme

The semi-fluid mass of partially digested food that moves from the stomach to the small intestine.

Digestion

The process of breaking down food into simpler nutrients for absorption.

Egestion

The removal of waste from the digestive tract; the excretion of undigested food.

Adhesion

The process by which molecules stick to surfaces, important in nutrient absorption in the digestive tract.

Absorption

The process by which nutrients from digested food are taken up by the blood or lymph.

Bile

A digestive fluid produced by the liver and stored in the gallbladder, essential for the emulsification of fats.

Gastrointestinal Tract

The series of hollow organs that food passes through from the mouth to the anus.

Ingestion

The intake of food and liquids into the digestive system through the mouth.

Microvilli

Tiny hair-like structures on the surface of villi that further increase the surface area for nutrient absorption.

Pancreatic Juice

A digestive fluid secreted by the pancreas containing enzymes that help in the digestion of proteins, fats, and carbohydrates.

pH

A measure of acidity or alkalinity; stomach acid has a low pH to aid in digestion.

Protease

An enzyme that breaks down proteins into smaller peptides and amino acids.

Small Intestine

The part of the gastrointestinal tract where most chemical digestion and nutrient absorption occurs.

Sphincter

A circular band of muscle that constricts or dilates to control the passage of substances in the digestive tract.