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9 Cards in this Set
- Front
- Back
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Functions of Digestive System:
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Process food, extract nutrients and
eliminate residue Occurs in five stages Ingestion Digestion Absorption Compaction Defecation |
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Small Intestine Brush Border:
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High surface area
due to microvilli Secretes enzymes Capillaries and lymph vessels for absorption |
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Chemical Digestion:
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Macromolecules process=hydrolysis
Break covalent bonds between monomers Accomplished with enzymes and secretions Occurs in mouth, stomach and small intestine Dehydration syntheses=production macromolecules Chemical digestion=opposite of dehydration synthesis |
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Absorption:
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Absorption:
-move monomers from gut into cells lining intestine -leave cells to enter blood or lymph Food, drink and GI secretions can equal up to 10 liters per day Less than 1 liter enters large intestine All food molecules, 80% of electrolytes and most water are absorbed in small intestine |
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Carbohydrates:
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Monomer =monosaccharide
What do we ingest? -monosaccharides, disaccharides, and polysaccharides Chemical digestion -begins with saliva=amylase -continues in small intestine -pancreas=amylase -brush border=sucrase, maltase, and lactase Absorption -glucose and galactose=sodium symporter -fructose=facilitated diffusion |
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Proteins:
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Monomer = amino acid
What do we ingest?- Meat, enzymes, protein, cells Chemical digestion -begins in stomach=pepsin -continues in small intestine -pancreas=trypsin and chymotrypsin -brush border=peptidases Absorption -cotransport with sodium ions -1-3 amino aids moved together -secondary active transport |
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Lipids:
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Monomer = fatty acids and glycerol
-don't like water, nonpolar What do we ingest?: adipose, saturated and unsaturated fatty acids, oils, plasma membrane, cholesterol Chemical digestion -begins in stomach -salivary glands secrete lipase -activated in stomach -continues in small intestine -bile added=emulsion -pancreas=lipase Absorption -Bile + fatty acids form micelles -move out of gut by simple diffusion One inside cells -chylomicrons formed -repackaged to triglycerides -coated with phospholipids -enter lymph through lacteals (tiny little green vessels in microvilli, along with capillaries) |
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Nucleic Acids:
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Monomer = nucleotide
What do we ingest? Nuclei in all cells Chemical digestion -begins in small intestine pancreas=ribonuclease and deoxyribonuclease brush border enxymes -break down to phosphate, N base and sugar Absorption -by active transport |
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Vitamins and electrolytes:
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Fat soluble vitamins
-A,D,E,K -move with micelles Water soluble vitamins -B and C -Move by simple diffusion and active transport B12 –if not absorbed properly could cause pernitious anemia - Intrinsic factor -move through intestines using endocytosis Iron -active transport into cells -binds ferritin -enters blood as need with transferritin |
