The Digestive System Chapter 22-3

Science Words/Objectives Digestion Mechanical digestion Chemical digestion Saliva Peristalsis Chyme Villi

Objectives Distinguish between mechanical and chemical digestion Mane the organs of the digestive system and describe what takes place in each Explain how homeostasis is maintained in digestion

Processing food Digestion- the process that breaks down food into small molecules so they can move into the blood. Introduction to Digestion

Digestive system Mouth Esophagus Stomach Small intestine Large intestine Rectum anus Does not pass thru the liver, pancreas, gallbladder- they produce or store enzymes and chemicals that help break down food as it passes through the digestive tract Parts of digestive system,

Enzymes Are molecules that speed up the rate of chemical reactions in your body. Enzymes in the mouth, stomach, small intestine,. Breaks down proteins and fats

Where and How digestion occurs Mechanical digestion-takes place when food is chewed and mixed in the mouth and churned in the stomach. Chemical digestion-breaks down large molecules to small molecules. Mouth, stomach and small intestine Forms of Digestion

Mouth Mechanical digestion starts with your teeth. Chemical digestion starts with your saliva. Saliva-produced by 3 glands, is water, mucus, and salivary amylase(enzyme) Moved by tongue- swallowed into esophagus. The Mouth

Esophagus Muscular tube 25 cm long, 4-10 seconds to go through it No digestion takes place Smooth muscles move food by squeezing. Peristalsis- waves or contractions The Esophagus

Stomach Is a muscular Bag. As food enters it expands and the folds smooth out Mechanical and chemical digestion Changes into a thin watery liquid called chyme, which goes into the small intestine The Stomach

Small Intestine 4-7 meters in length Enters the duodenum where most of all digestion takes place. Liver produces bile to help break down food Pancreas produces enzymes to break down fats and proteins Gall Bladder and Pancreas Small Intestine

Small intestine The small intestine has ridges and folds, the folds are covered with tiny fingerlike projections called villi. Villi make the surface of the intestine greater so that there are more places for food to be absorbed.

Large Intestine Main job is to absorb liquid from chyme- undigested materials become more solid. Large intestine

The Role of Bacteria Bacteria feed on cellulose and produce several vitamins that you need

Digestion and Nutrients

Homeostasis The regulation of steady, life maintaining conditions inside an organism or cell, despite changes in its environment. Water is removed and returned to the body

References Glencoe Life Science UnitedStreaming.com Adam.com