The Digestive System Coachbook, pages 67-68

your cells use nutrients to produce energy-they come from food Getting the Idea: your cells use nutrients to produce energy-they come from food Breaking food down for energy also produces wastes. wastes must be removed from the body.

Two of your body systems break food down &and remove wastes products from your body. Digestive & Excretory

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

Digestion begins in the mouth teeth grind, crush, and break mechanical digestion.

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

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 The stomach is a muscular organ mechanical digestion-contracting and squeezing its contents. Glands in the stomach produce enzymes and acids (chemical digestion. )

Dinosaur Stomach

Small Intestine Food remains in the stomach for several hours!! The stomach digests the food into a liquid. This liquid then enters the small intestine, a long, muscular tube where the body absorbs nutrients from food.

The Pancreas The pancreas is a gland that releases digestive enzymes into the small intestine. Produce insulin substances neutralize stomach acids, which could damage the lining of the intestine and prevent enzymes from doing their job.

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

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 is moved by peristalsis into the large intestine.

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

The Large Intestine The large intestine :both the digestive and excretory Function: absorb water from the undigested material. compacts the solid wastes 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.

Mouth Esophagus Liver Pancreas Stomach Large Intestines Small Intestines Rectum

Digestion Drying Absorption