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…