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Accessory Digestive Organs. Teeth Salivary glands Pancreas Liver Gallbladder. Functions of the Digestive System. Food breakdown as mechanical digestion Breaking large pieces into small pieces (increase surface area) P repares food for further degradation by enzymes Examples:
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Accessory Digestive Organs • Teeth • Salivary glands • Pancreas • Liver • Gallbladder
Functions of the Digestive System • Food breakdown as mechanicaldigestion • Breaking large pieces into small pieces (increase surface area) • Prepares food for further degradation by enzymes • Examples: • Mixing food in the mouth by the tongue • Churning food in the stomach • Segmentation in the small intestine
Functions of the Digestive System • Food breakdown as chemical digestion • Enzymes break down food molecules into their building blocks • Each major food group uses different enzymes • Carbohydrates (polysaccharides/starches) are broken to simple sugars monosaccharides/glucose) • Proteins (peptides) are broken to amino acids • Lipids (Fats) are broken to fatty acids and glycerol *Cellulose is a carbohydrate that cannot be broken down by our digestive system and is referred to as ruffage or fiber- it helps clean the system
Teeth • Function is to masticate (chew) food • Humans have two sets of teeth • Deciduous (baby or “milk”) teeth • 20 teeth are fully formed by age two • Permanent teeth • Replace deciduous teeth between the ages of 6 and 12 • A full set is 32 teeth, but some people do not have wisdom teeth (third molars) • If they do emerge, the wisdom teeth appear between ages of 17 and 25
Salivary Glands • Three pairs of salivary glands empty secretions into the mouth parotid sublingual submandibular
Saliva • Contains mucus, helps to form a food bolus • Contains salivary amylase to begin starch digestion • Has antimicrobial properties and contains phagocytes • Dissolves chemicals so they can be tasted • Is continuously made throughout the day, peeking in the afternoon • Can also be stimulated to produce more saliva at other times (mouth waters)
Pancreas • Found posterior to the parietal peritoneum • Extends across the abdomen from spleen to duodenum • Connected to the duodenum via various ducts
Pancreas • Produces buffer (alkaline substance) • Neutralizes stomach acids still in the chyme • Produces enzymes • Pancreatic amylase: continues the breakdown of starch into glucose • Protease: breaks proteins into amino acids • Lipase: breaks fat into fatty acids and glycerol
Liver • Largest gland in the body • Located on the right side of the body under the diaphragm • Consists of four lobes • Connected to the duodenum via the common hepatic duct
Liver • Produces bile: a yellow-green substance • Physically breaks down fat to increase surface area: process known as emulsification • Stored in the gall bladder
Gall bladder • Sac-like structure • Found embedded in the lower liver • Stores bile backed up in the duct • Hormonally controlled to release bile to duodenum