What Happens to Food Once it Enters Your

Mouth?

Digestion – the process that breaks down food into

small molecules that can be absorbed and moved into blood. • Mechanical

Digestion: takes place when food is chewed, mixed, and churned.

• Happens in the mouth, esophagus, and stomach.

• Chemical Digestion: takes place when chemical reactions break down large food molecules into smaller ones.

• Happens in the mouth, stomach, small intestine.

Enzymes

• Proteins that speed

up reactions without

being used up.

• Enzymes are very

important to the

digestive process.

Organs of the Digestive System

• Digestive Tract – mouth, esophagus, stomach, small intestine, large intestine, rectum, anus. All food passes through these organs.

• Accessory Organs – tongue, teeth, salivary glands, liver, gall bladder, and pancreas. Liver, gall bladder, and pancreas make and store enzymes.

The Mouth – both mechanical and chemical digestion happen here.

The Esophagus

• About 25 cm long.• Takes about 4-10

seconds for food to reach the stomach.

• Peristalsis moves food down the esophagus.

• No digestion occurs here.

The Stomach

• Mechanical and chemical digestion happen here.

• Hydrochloric acid and enzymes break down food and kill bacteria.

• Food leaves in 2-4 hours as a thin, watery liquid called chyme.

The Small Intestine

• About 4-7 m in length.• Many enzymes are

mixed with food here.• Covered with villi to

increase surface area.

• Food molecules are absorbed here and released into the bloodstream.

Small Intestine and Villi

Large Intestine

• Main job is to absorb water back into the body from chyme.

• Peristalsis slows down here meaning food stays for up to 3 days.

• Semi-solid wastes are released by the rectum and anus.

Bacteria• Are very important to the digestive

process.

• Feed on undigested material in large intestine.

• Produce vitamins.

• Also produce gas.

Digestive System

• Chemical and physical digestion.

• Ingestion happens in the mouth; digestion occurs in the mouth, stomach, and small intestine; absorption occurs in the small and large intestine.

• Accessory organs move and cut up food and supply enzymes and other chemicals.

• Large intestine reabsorbs water.

One last look…