Chapter 16, Section 2The Digestive Process Begins

Wednesday, March 3, 2010

Pages 518 -- 523

Objectives

• Describe the general functions carried out by the digestive system.

• Describe the specific functions of the mouth, esophagus, and stomach.

Vocabulary Words

• Digestion• Absorption• Saliva• Enzyme• Epiglottis

• Esophagus• Mucus• Peristalsis• Stomach

Digestive System Functions

• Breaks down food into molecules the body can use (Digestion).

• Molecules are absorbed into the blood and carried throughout the body (Absorption).

• Wastes are eliminated from the body (Elimination).

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The Mouth

• Digestion begins in the mouth– Teeth cut and tear

food into smaller pieces.

– Saliva plays an important role in the mechanical and chemical digestive process.

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Mechanical Digestion

• Begins with the first bite of food.

• Your teeth begins the process by grinding and cutting your food into smaller pieces.

• Saliva mixes with the food and moistens them to make swallowing easier.

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Chemical Digestion

• Chemical digestion also begins in the mouth.

• It is the breakdown of complex molecules into simpler ones.

• This process is aided by enzymes.

The Esophagus• When you swallow,

muscles in your throat move the food downward.

• The epiglottis seals off your windpipe to prevent food from entering.

• Food enters the esophagus - a muscular tube that connects the mouth to the stomach.– Esophagus lined with

mucus

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The Stomach

• J-shaped organ.– Muscular pouch located

in the abdomen.– Expandable to hold about

2 liters of food.– Chemical and

mechanical digestion happens here.

• Food is further broken down by digestive juices.

– Lined with mucus which coats and protects the lining of the stomach.

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Homework

• Workbook 16.2 (3/5)

• Vocabulary quiz 16.2 (3/5)