The Digestive System Coachbook, pages 67-68

Breaks down food into nutrients Nutrients used by cells for energy Getting the Idea: Breaks down food into nutrients Nutrients used by cells for energy Waste must be removed

The Digestive System group of organs that break food down into molecules that are small enough to be absorbed by and transported throughout the body by blood.

teeth grind, crush, and break apart your food. The Mouth teeth grind, crush, and break apart your food. Breaking food into smaller pieces is known as mechanical digestion.

Saliva moistens the food so it is easier to swallow. contains an enzyme that begins to break down starches and sugars. An enzyme is a protein that speeds up a chemical reaction.

When food has been chewed enough, it is moved to the back of the mouth for swallowing. After food is swallowed, it passes the epiglottis, a flap of tissue that covers the opening of the trachea to keep food out. The food then moves into the esophagus.

The Esophagus The esophagus is a muscular tube that connects the mouth to the stomach. Contractions of the muscles in the wall of the esophagus push the food toward the stomach. These contractions are called peristalsis.

Mouth and Esophagus Mouth Esophagus Teeth - break up the food. (Mechanical Digestion) Saliva- chemical in the mouth that begins digestion. (Chemical Digestion) Esophagus Tube that connects the mouth to the stomach.

The Stomach J- shaped muscular organ. Most mechanical digestion occurs here Food is turned into a thick, brown fluid called chyme.

Dinosaur Stomach

Small Intestine Chyme enters the small intestine a long, muscular tube where the body absorbs nutrients from food using villi- fingerlike projections Most chemical digestion occurs here

The Pancreas The pancreas is a gland that releases digestive enzymes and other chemicals into the small intestine.

The Liver The liver also helps with digestion in the small intestine. The liver is an organ that makes bile, a liquid that helps to break down fat.

The Gall Bladder The bile produced by the liver is temporarily stored in the gall bladder.

Absorption in the Small Intestine Once food is digested, nutrients are absorbed through the walls of the small intestine. The walls of the small intestine have many folds called villi, which increase the surface area that can absorb digested food.

Villi greatly increase the surface area of the small intestine. Laid out, it would be equal to the surface of a tennis court.

Villi Nutrients enter the bloodstream through the capillaries in the villi. The blood then transports the nutrients to all the cells of the body. Any undigested material left in the small intestine is moved by peristalsis into the large intestine.

Peristalsis Waves of muscle contractions that pushes food through the digestive tract.

The Large Intestine The large intestine is an organ of both the digestive system and the excretory system. Its role in digestion is to absorb water from the undigested material. The large intestine also compacts the solid wastes that remain from undigested food.

The Large Intestine continued… The remaining material is ready for elimination from the body. Rectum- a short tube that is the last portion of the large intestine. Waste material is pressed into a solid form. Waste material exits through the anus, a muscular opening at the end of the rectum.

Rectum Opening And Closing

Mouth Esophagus Liver Pancreas Stomach Large Intestines Small Intestines Rectum

Digestion Drying Absorption