Digestive System

Functions of the Digestive System 1. It breaks down food into molecules the body can use. 2. The molecules are absorbed into the blood and carried throughout the body 3. Wastes are eliminated from the body.

Definitions: Digestion: process by which your body breaks down food into small nutrient molecules. Absorption: the process by which nutrient molecules pass through the wall of your digestive system into your blood. Nutrients not absorbed (fiber) are eliminated as waste.

The Mouth Both Mechanical & Chemical Digestion begin here. Mechanical Digestion: Teeth tear/slash food into smaller particles. Chemical Digestion: Saliva is produced. Moistens food and enzymes in the saliva begin to break carbohydrates down. Mechanical Mechanical Chemical Chemical

The Esophagus A muscular tube that connects the mouth to the stomach Lined with mucus (thick slippery substance) that allows the easy passage of food Contractions of the smooth muscle pushes the food forward (peristalsis)

The Stomach “J” shaped muscular pouch Most Mechanical Digestion (and some Chemical) occur here Churning of food (mechanical) and mixing with digestive juices (chemical) Main digestive juice: hydrochloric acid Food remains in the stomach and becomes a liquid known as chyme.

Small Intestine Chyme leaves the stomach and enters the small intestine Most chemical digestion takes place as well as absorption

Liver Located in upper right of abdomen Produces Bile Bile is a substance that breaks up fat Stored in the gallbladder, then secreted into small intestine when food is present.

Pancreas Triangular shaped organ Produces enzymes that help break down starches, proteins and fats.

Absorption in the Small Intestine Inner surface of small intestine is covered with finger like projections called villi It is along the villi that absorption takes place Villi increase the absorption surface area

The Large Intestine What remains after the absorption process passes to the large intestine 1.5 meters long Water is absorbed, the rest is passed out of the body. Bacteria in the large intestine will help break down some waste.