GSU BIOL 2240 - Digestion_Nutrition_Absorption_ (23 pages)

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Digestion_Nutrition_Absorption_



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Digestion_Nutrition_Absorption_

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Pages:
23
School:
Georgia State University
Course:
Biol 2240 - Intro to Human Physiology
Intro to Human Physiology Documents
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Digestion Nutrition Absorption Anatomy of the Digestive System 2 groups of organs Alimentary tract aka GI tract Mouth or oral cavity Pharynx throat Esophagus Stomach Small intestine duodenum ileum jejunum Large intestine and Anus Accessory organs Teeth tongue gallbladder salivary glands liver and pancreas Functions of the Digestive System Ingestion introduction of food into body by mouth Mastication chewing breaking down large particles mechanically to facilitates chemical digestion Secretion lubricate liquefy digest contents Mucus secreted along entire digestive tract lubricates food and lining coats lining and protects it from mechanical damage from acid and from digestive enzymes Bile emulsifies fats from liver and gall bladder Enzymes chemical digestion from saliva stomach pancreas small intestine Digestion Mechanical churning and chemical Absorption Movement from gi tract into circulation diffusion active transport symport exocytosis or lymph Elimination Defecation Waste products removed from body feces Oral Cavity Mastication Mechanical digestion teeth and tongue Chemical digestion Saliva Salivary amylase breaks down starch Polysaccharides into disaccharides starts chemical digestion Anti bacterial Contains lysozymes Histology of the Stomach Gastric pits openings for gastric glands Cells of gastric pits mucus mucus that protects Parietal produces hydrochloric acid Chief pepsinogen Endocrine produces hormones Secretions of the Stomach Mucus lubrication of digestive tract Pepsinogen converted to Pepsin by HCl Breaks down proteins HCl produced by parietal cells Helps convert pepsinogen to pepsin Kills bacteria Denatures proteins e g salivary amylase Stops carbohydrate digestion by inactivating salivary amylase Hydrochloric Acid Production Small Intestine Site of greatest amount of digestion and absorption of nutrients and water Divisions DuodenumJejunum Ileum Small Intestine Duodenum bile released into duodenum from gall bladder and liver Villi that contain capillaries and lacteals Microvilli folds of cell membranes of absorptive cells Site of nutrient carbohydrates lipids and proteins absorption Cystic duct Common hepatic duct Bile duct and sphincter Pancreas Gallbladder Major duodenal papilla Hepatopancreatic ampulla Duodenum Main pancreatic duct and sphincter Head of pancreas Microvilli brush border Absorptive cells Lacteal Goblet cell Blood capillaries Mucosa associated lymphoid tissue Intestinal crypt Vilus Enteroendocrine cells Muscularis mucosae Venule Duodenal gland Submucosa b Lymphatic vessel Pancreas Pancreas both endocrine and exocrine Endocrine pancreatic islets Produce insulin and glucagon Exocrine acinar cells release digestive enzymes e g trypsinogen and bicarbonate HCO3 into duodenum pancreas Carbohydrates Carbohydrate absorbed by small intestine as monosacharides glucose galactose and fructose Body converts galactose and fructose to glucose to be used for ATP synthesis diffusion Symport Active transport Lipids Bile salts surround lipids to form micelles Lipids absorbed by small intestine as monoglycerides Chylomicrons enter blood stream thru lymph lacteals glycerols and fatty acids Amino Acid Transport Proteins absorbed by small intestine mostly as dipeptides two amino acids Large Intestine Bacteria produce vitamin K and vitamin B12 which is then absorbed Water is reabsorbed Glucose galactose fructose And glycerol Nutrition Chemicals taken in to body to produce energy provide building blocks or function in other chemical rxns Classes Carbohydrates lipids proteins water required in large amounts Vitamins minerals required in small amounts Essential nutrients must be ingested cannot be synthesized Certain amino acids certain fatty acids most vitamins minerals water Carbohydrates Most come from plants Monosaccharides include glucose fructose galactose Disaccharides include sucrose Polysaccharides complex include starch glycogen cellulose Cellulose is indigestible Carbohydrates Uses in the Body Digestion breaks poly and disaccharides into monosaccharides before absorption Liver converts monosaccharides into glucose which is then used as an energy source to produce ATP Excess glucose converted to glycogen and stored in muscles and liver cells Excess beyond storage is converted to fat Lipids Triglycerides 95 ingested glycerol 3 FAs e g Linoleic acids essential fatty acids Found in fish seeds nuts legumes grains and green leaves Cholesterol found in animals but not in plants sterol Phospholipids major components of plasma membranes e g egg yolks glycerol phosphate choline 2 FAs Lipids Uses in the Body Triglycerides used to produce ATP Excess stored in adipose tissue or liver Cholesterol Component of plasma membranes Can be eaten or manufactured in the body Phospholipids part of plasma membrane and used to construct the myelin sheath Proteins Chains of amino acids Types Essential must be obtained in diet His iso leu lys met phe thr try val Nonessential body can synthesize Complete proteins contain all necessary amino acids meat fish poultry milk cheese eggs Minerals Inorganics necessary for normal metabolic functions Functions establish resting membrane potentials generate action potentials add strength to bones and teeth buffers involved in osmotic balance Components of hemoglobin bone etc Obtained from animal and plant sources Metabolic States 2 Absorptive state period immediately after eating when nutrients absorbed through intestinal wall into circulatory and lymphatic systems for up to 4 hours after each meal Insulin released for uptake of Glucose into cells Postabsorptive state After absorptive state Blood glucose levels maintained by conversion of other molecules to glucose Glucagon released to break down glycogen to glucose


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