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34 Cards in this Set
- Front
- Back
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digestive system |
-aka the gastrointestinal (GI) tract -function: ingestion of foods (physical & chemical breakdown) -absorption of the nutrients |
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mechanical vs chemical digestion |
mechanical: grinding/mashing of food to allow more surface area for chemical digestion chemical: breakdown of macromolecules by enzymes into their building blocks so they can be absorbed into the blood |
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nutrients |
provide the body with E and the raw materials to make organic molecules |
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macromolecules |
large complex assembly of organic molecules |
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assembling macromolecules vs disassembling macromolecules |
assembling macromolecules: -dehydration synthesis = a molecule of water is removed while a new organic molecule is formed -to form a bond between 2 different molecules, a hydroxyl (-OH) group is removed from one group and a hydrogen atom is removed from the other disassembling macromolecules: -reverse of dehydration synthesis -hydrolysis = water is added and hydrogen and the hydroxyl break a part and each join a separate polymer (requires enzyme) |
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types of macromolecules (x6) |
1. carbohydrates 2. lipids 3. proteins 4. nucleic acids 5. vitamins 6. minerals |
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Carbohydrates |
-sugar, starch, glycogen (long term storage in the liver) -store energy -most are glucose or POLYMERS of glucose -simple sugars (monosaccharide): molecule with three to seven carbons -polysaccharide: complex carbohydrate made up of many simple sugars |
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Lipids |
-fats, oils, phospholipids; insoluble in water -some used for energy storage -phospholipids & cholestorol make up membranes -steroids can be hormones: regulate growth & reproductive functions |
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Proteins |
-made up of amino acids -very diverse and complex: i. give structure to the body ii. carrier or transportation molecules iii. enzymes -bonded together through peptide bonds -a chain of amino acids are called peptides or a poly peptide |
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Nucleic Acids |
-DNA, RNA, and ATP -make up genetic material of cell and carry energy -direct growth in all organisms |
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Vitamins |
-organic compounds with carbon, hydrogen, & other elements
-only needed in small quantities -most vitamins help enzymes to function more effectively |
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Minerals |
-inorganic (do not contain carbon) -only needed in small quantities -make up bones, parts of some enzymes & proteins -are needed to bind to some proteins |
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enzymes |
proteins that speed up chemical reactions in the body -specific to substrate: "lock & key model" |
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factors that affect enzyme activity (x4) |
(a) temperature -but high temps (over 40 degrees celsius) can denature the enzyme stopping it from working -enzymes work at an optimum temp (b) pH -some enzymes work best under different pH's -changes in H+ (change the shape of the enzyme & prevent it from working) -optimum pH (c) concentration of substrate -enzymes work slowly with low substrate concentration -usually more substrate increase reaction rate (d) concentration of enzyme -usually the presence of more enzyme will increase the rxn rate, providing there is an unlimited supply of substrate |
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inhibitors of enzyme activity (x2) |
i. competitive inhibitors -compete with substrate for the active site -can be replaced with substrate (reversible) -degree of inhibition depends on the concentration of the inhibitor & substrate ii. non-competitive inhibitors -when the inhibitor does not bind to the active site but with a different part of the enzyme -causes a deformation of the active site making it harder to bind |
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carbohydrate digestion |
broken down by enzymes called "carbohydrases" found in the saliva & released by the pancreas 1. amylase + complex starch & glycogen --> many maltose 2. maltase + maltose --> 2 glucose 3. sucrase + sucrose --> glucose + fructose 4. lactase --> glucose + galactose |
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lipid digestion |
broken down by lipases from the pancreas -fat must be emulsified by bile salts so that it surface area increases for pancreatic lipases -Lipases + lipid ---> glycerol + fatty acids |
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protein digestion |
broken down by proteases released by the stomach & pancreas 1. pepsin (stomach) + protein ---> small polypeptides 2. trypsin & chymotrypsin (pancreas) + polyceptides ---> smaller peptides 3. peptidases (pancreas) + peptides ---> amino acids |
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nucleic acid digestion |
digested by nucleases released by pancreas & embedded in the small intestine 1. nucleases (pancreas) + nucleic ---> nucleotides 2. nucleosidases (small intestine) + nucleotides ---> bases, sugars, phosphates |
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parts of the digestive system (x8) |
mouth esophagus stomach small intestine pancreas liver gall bladder large intestine |
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mouth |
-tears food to increase surface area of food -moves bolus toward esophagus for swallowing -secretion = saliva; contains salivary amylase |
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esophagus |
-muscular tube -propels food bolus to stomach by peristalsis, a series of coordinated muscle contractions -esophageal sphincter: plugs the top of the stomach to prevent acid from moving upward (acid reflux or heartburn) |
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stomach |
-peristalsis grinds up food -cells lining the stomach secrete gastric juice for digestion & mucous for protection -chyme: food and gastric juice leaving the stomach through the pyloric sphinctor -gastric juice: contains hydrochloric acid & enzymes that digest proteins (pH 1-3, pepsin is secreted in an active form so it does not destroy the stomach |
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why doesn't the stomach digest itself? |
-the stomach only secretes gastric juice when food is present -mucous protects the stomach lining -pepsin is inactive until HCL is present |
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small intestine |
-final site of chemical digestion & most nutrient absorption -made up of ridges called villi & each villus has thousands of microscopic ridges called microvilli 1. duodenum 2. jejunum 3. ileum |
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segmentation |
the process by which the chyme sloshes back and forth between the different segments of the small intestine |
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pancreas |
secretes pancreatic fluid into the duodenum -contains digestive enzymes: trypsin & chymotrypsin ("proteases"), amylase (carbohyrase), lipase, nucleases -contains biocarbonate to neutralize the stomach acid -also secretes hormones insulin & glucagon to regulate sugar metabolism |
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liver |
largest internal organ -secretes bile (where bile is made) |
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gall bladder |
small green sack under liver -where bile is stored -when chyme enters the duodenum, it causes the gall bladder to squeeze bile through a duct into the duodenum |
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large intestine |
"trash compactor" -concentrates & eliminates waste materials |
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nutrient absorption |
-carbohydrates absorbed as simple sugars -proteins absorbed as fatty acids & glycerol -nucleic acids absorbed as sugars, bases & phosphates -lipids absorbed as amino acids |
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colon |
-eliminates undigested/unabsorbed wastes -absorbs water & salt to concentrate wastes -bacteria that live in the colon break down some digested foods & produce some vitamins |
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rectum |
last 20 cm of the large intestine -feces passes through the rectum by peristalsis -three folds in the rectum allow feces to be stored while gas is passed -the anus opening is under the control of 2 sphincters: one is under conscious control |
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nutrient absorption: carbohydrates/proteins/nucleic acids vs fats |
fats: chylomicrons are absorbed in the LYMPH carb./proteins/n.a.: absorbed by ATP & released into the BLOODSTREAM |
