Digestive System

A group of organs that work together to break down food so that it can be used by the body. Digestive Tract: organs the food passes through; includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. Also includes liver, gall bladder, pancreas, and salivary glands. Takes food about 24 hours to pass through the digestive tract.

Breaking Down Food Digestion: the process of breaking down food into a form that can pass from the digestive tract to the bloodstream. Two types of digestion: 1.Mechanical- breaking, crushing, and mashing of food. 1.Chemical- large molecules are broken down into nutrients.

Enzymes are substances that break some nutrients into smaller particles. Nutrients are substances needed for energy, growth, maintenance, and repair. 1.Carbohydrates (sugars) 2.Proteins (amino acids) 3.Lipids (fats)

Mouth Chewing creates smaller pieces of food that are wet and easier to swallow. Teeth perform mechanical digestion. Covered in enamel, the hardest material in the body which protects the interior of teeth. Saliva that is made in the salivary glands contains enzymes that begin chemical digestion of carbohydrates.

Pharynx Tube that connects mouth to esophagus.

Esophagus Food is pushed by the tongue into the throat that leads to this long straight tube. Esophagus squeezes the food with muscle contractions called peristalsis (mechanical digestion).

Stomach Small, muscular, saclike organ attached to the lower end of the esophagus. Continues mechanical digestion via peristalsis. Tiny glands produce enzymes and acids that chemically break down food. Stomach acid kills bacteria also. Food is eventually reduced into chyme, a soupy mixture.

Small Intestine Muscular tube longer than you are tall! Called “small” due to small diameter. Valve allows chyme to enter in small amounts. Most chemical digestion occurs here. Absorption of nutrients. Covered in villi which absorb nutrients that enter the bloodstream to be delivered to cells in the body.

Pancreas Between the stomach and small intestine. Food does NOT pass through. Makes enzymes and bicarbonate (acid neutralizer) that protect the small intestine. Also makes hormones that regulate blood sugar.

Liver Reddish, brown organ located toward the right side of the body. Food does NOT pass through. Makes bile to break up fat, stores nutrients, and breaks down toxins. Detoxifies many chemicals, such as alcohol and drugs.

Gall Bladder Temporarily stores the bile made by the liver. Bile breaks down large fat droplets so more of the fat can be exposed to digestive enzymes.

Large Intestine Most of the water in the leftover chyme is absorbed here. Water and indigestible materials are stored and compacted into feces. Cellulose which comes from plants we eat, cannot be digested. This “fiber” keeps feces soft and moving through the intestines. Rectum stores feces until elimination. Anus is the opening through which the feces pass out.

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