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DIGESTIVE SYSTEM Pages 979-991 FUNCTION •Breakdown of food into simpler molecules that can be absorbed by the body in one long tube from mouth to anus NUTRIENTS •Six classes of nutrients: 1. 2. 3. 4. carbohydrates fats/lipids proteins minerals: help balance osmosis and the function of certain cells (i.e. muscle and nerve cell) 5. vitamins: aid enzyme activity 6. water: most chemical reactions can only occur in water (accounts for half of your body weight) DIGESTION •Mechanical: physical breakdown of food •Chewing, peristalsis (moving bolus down the esophagus), and stomach churning DIGESTION •Chemical: enzymes breaking down food into simpler forms (monomers) •Ex: amylase and pepsin PARTS OF THE DIGESTIVE TRACT •Mouth •Amylase (enzyme) is released from glands into saliva •Breaks down carbohydrates to monosaccharides DIGESTIVE TRACT •Esophagus (connects mouth to stomach) •Bolus (food ball) travels down esophagus to stomach DIGESTIVE TRACT •Stomach •Muscle contractions break bolus apart (mechanical digestion) DIGESTIVE TRACT Stomach continued •Pepsin (enzyme) breaks down proteins into amino acids (chemical digestion) •Released by gastric glands •HCl keeps stomach acidic so the pepsin can work DIGESTIVE TRACT •Pancreas •Secretes sodium bicarbonate (base) into small intestine to neutralize acid DIGESTIVE TRACT •Liver •Produces bile and sends it to the gall bladder for storage DIGESTIVE TRACT •Gall bladder •Stores bile and secretes it into the small intestine DIGESTIVE TRACT •Small intestine •Chemical digestion and where most nutrients are absorbed •Bile is secreted here to break down fats into fatty acids DIGESTIVE TRACT •Small intestine continued •Has villi: folds in lining of small intestines •Increases surface area for maximum absorption DIGESTIVE TRACT •Large intestine/colon •Absorption of water, minerals, and vitamins Salivary glands Esophagus Liver Stomach Gall bladder Pancreas Small intestine Large intestine/colon