The Digestive System The digestive system consists of an alimentary canal and several accessory organs.

The Digestive System The digestive system mechanically and chemically breaks down food. Mechanical digestion includes chewing and peristalsis. Chemical digestion includes the use of enzymes.

The Digestive System Digestion = Big Little Food Nutrients Nutrients = carbohydrates sugars fats fatty acids + glycerol proteins amino acids

The Digestive System Essential nutrients are absorbed into the body and the unused waste material is excreted out of the body.

The Digestive System The Alimentary Canal

The Digestive System The Alimentary Canal A. Wall Layers 1. Mucosa Structure: composed of epithelial, connective, and smooth muscle tissue; mucus secreting glands present Function: protection, absorption, secretion 2. Submucosa Structure: composed of loose connective tissue; glands, blood and lymph vessels present Function: nourishment

The Digestive System The Alimentary Canal A. Wall Layers 3. Muscular layer Structure: composed of 2 layers of smooth muscle; circular and longitudinal shaped fibers Function: movement 4. Serosa Structure: composes the outer layer of the canal Function: secretion of fluid to lubricate so tube can slide feely

The Digestive System IV. The Oral Cavity

The Digestive System V. The Teeth

The Digestive System VI. The Pharynx

The Digestive System VII. The Salivary Glands

The Digestive System VIII. The Stomach

The Digestive System IX. The Small Intestine

The Digestive System X. The Large Intestine

The Digestive System XI. The Liver

The Digestive System XII. The Gall Bladder and Pancreas

Overview Salivary Glands (amylase) Oral Cavity Esophagus Stomach (HCL and pepsinogen = pepsin) Pancreas (lipase, amylase, trypsin, chymotrypsin, carboxypeptidase: pancreatic juice) Blood (fatty acids, glycerol, amino acids, monosaccharides) Small Intestine (peptidase, lipase, sucrase, maltase, lactase) Liver/Gall Bladder (bile/bile salts) Large Intestine (bacteria = intestinal flora) Blood (water, electrolytes, vitamins) Rectum

The Digestive System Digestion = Big Little Food Nutrients Nutrients = carbohydrates sugars fats fatty acids + glycerol proteins amino acids

Chemical Digestion and Nutrients Carbohydrates Uses in the Body: used primarily to supply energy for cellular processes

Chemical Digestion and Nutrients Carbohydrates Dietary Sources: - starch from grains and vegetables - glycogen from meats - monosaccharides from honey and fruits Dietary Requirements: - Varies among individuals - Depends on amount of physical activity, body size and metabolic rate.

Chemical Digestion and Nutrients Carbohydrate Digestion (starch to monosaccharide) Pancreas Chemical digestion by pancreatic amylase (breaks down carbohydrates into disaccharides) Mouth Mechanical digestion Chemical digestion by salivary amylase (breaks down carbohydrates into disaccharides) Small Intestine Chemical digestion by sucrase, maltase + lactase (break down disaccharides into monosaccharides: sucrose…) Stomach Mechanical digestion Small Intestine Glucose absorbed into blood

Chemical Digestion and Nutrients Lipids Uses in the Body: -supplies energy for cellular processes and for building cellular structures

Chemical Digestion and Nutrients Lipids Dietary Sources: - saturated fats found in meats, eggs and milk - unsaturated fats found in seeds, nuts and plant oils - monosaturated fats found in olive, peanut and canola oils Dietary Requirements: - Recommended to be less than 30% of total calories - Depends on amount of physical activity, body size and metabolic rate.

Chemical Digestion and Nutrients Lipid Digestion (fat to glycerol + fatty acid) Liver/ Gall Bladder Mechanical digestion by bile (bile crystallizes into bile salts and aid in lipid breakdown) Pancreas Chemical digestion by pancreatic lipase (breaks down lipids) Mouth Mechanical digestion Stomach Mechanical digestion Small Intestine Chemical digestion by intestinal lipase (breaks down lipids) Small Intestine Glycerol and fatty acids absorbed into lymphatic system.

Chemical Digestion and Nutrients Proteins Uses in the Body: - all cells in your body make proteins. In order to synthesize proteins, body needs a supply of amino acids (from food). - enzymes, clotting factors, keratin of skin and hair, collagen of connective tissue, plasma proteins, muscle proteins, hormones and antibodies.

Chemical Digestion and Nutrients Protein Dietary Sources: - meats, fish, poultry, cheese, eggs and cereals Dietary Requirements: - Between 60 to 150 grams per day - Depends on amount of physical activity, body size and metabolic rate.

Chemical Digestion and Nutrients Protein Digestion (protein to amino acids) Pancreas Chemical digestion by trypsin, chymotrypsin + carboxypeptidase (break specific bonds between amino acids) Stomach Mechanical digestion Chemical digestion by HCl acid and pepsin  pepsinogen (breaks specific bonds between amino acids) Small Intestine Chemical digestion by peptidase (breaks specific bonds between amino acids) Mouth Mechanical digestion Small Intestine Amino acids absorbed