Unit 2: Session 4: The Digestive System

Digestive System

The internal tube from mouth to anus and associated glands designed to move, break down, absorb, and eliminate food.

Main Function of Digestive System

Converts food into usable molecules for the body.

Ingestion

The act of eating or taking food into the mouth.

Digestion

The process of breaking food down into smaller parts, both mechanically and chemically.

Mechanical Digestion

The physical breakdown of food, such as chewing and churning.

Chemical Digestion

The breakdown of food using enzymes and other chemicals.

Absorption

The process of taking nutrients from digested food into the bloodstream.

Elimination (Egestion)

The removal of indigestible waste from the body as feces.

Mouth

The entry point of the digestive system where food is ground by teeth and mixed with saliva.

Teeth

Mineralized structures with a hard enamel surface that mechanically break down food.

Tongue

Moves food around in the mouth to aid chewing and swallowing.

Salivary Glands

Produce saliva that lubricates food and begins chemical digestion with the enzyme amylase.

Bolus

A small, rounded mass of chewed food ready to be swallowed.

Esophagus

Tube that delivers food from the mouth to the stomach using peristalsis.

Cardiac Sphincter

Valve that opens from the esophagus into the stomach.

Stomach

Acidic organ that produces pepsin and churns food into a semi-liquid called chyme.

Small Intestine

The main site of nutrient absorption, aided by villi and microvilli to increase surface area.

Pancreas, Liver, and Gallbladder

Accessory organs that produce enzymes, bile, and neutralize stomach acid for digestion.

Large Intestine

Absorbs water from chyme and forms feces for elimination.

Anal Sphincter

A muscle under voluntary control that regulates the release of feces through the anus.