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38 Cards in this Set
- Front
- Back
carbs
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carbs:
- cheapest E source, not often essential - sugars, starches, cellulose, gums - CF: cellulose, hemicellulose, lignin - NFE: starch, simple sugars |
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monosaccharides
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monosaccharides:
- cannot be further hydrolyzed - form stable rings in soln 1. pentose (5C): ribose, xylose 2. hexose (6C): glc, fru, gal |
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disaccharides
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disaccharides:
- 2 monos with loss of water 1. sucrose: glc + fru 2. lactose: glc + gal |
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bonds b/w sugars
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bonds b/w sugars:
1. alpha 1,6 and 1,4: starch and glycogen, bonds digested 2. beta 1,4: cellulose, cannot be hydrolyzed by mammalian or avian enzyme |
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trisaccharides
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trisaccharides:
- raffinose: glc, fru, gal |
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polysaccharides
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polysaccharides:
- polymers of many sugars 1. starch: - amylose (20-30%): alpha 1,4 - amylopectin (70-80%): alpha 1,6 2. cellulose: beta 1,4 |
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mouth digestion
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mouth digestion:
- salivary amylase 1. starch ---> dextrin 2. maltose, sucrose, and lactose remain intact |
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stomach digestion
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stomach digestion:
- salivary amylase 1. dextrin and maltose --> maltose, glc 2. sucrose and lactose intact |
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small intestine digestion
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SI digestion:
- enzymes: pancreatic amylase, sucrase, lactase, maltase 1. maltose + glc --> glc 2. sucrose --> fru + glc 3. lactose--> glc + gal |
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carb abs NR
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carb abs NR:
- monos primarily in duodenum and jejunum - little in stomach or LI - only newborns (24-48 hr) can abs di, tri or polysaccharides |
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glc and gal transport
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glc and gal transport:
1. Na-dependent glc transporter: - active, across SI 2. GLUT proteins in intestine and other cells: - facilitative, passive glc transport - specific mechanisms for other sugars not well defined |
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conversion into glc
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conversion into glc:
- glc is majority digested carb - conversion of gal and fru to glc in mucosal cells and hepatocytes |
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BG homeostasis
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BG homeostasis:
- normal NR: 80-100 mg/dl - preferred E source: CNS, RBC, gonads - GIT --> liver --> peripheral tissue use: 1. E sources for cells 2. muscle glycogen 3. fat synthesis |
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met after meal
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met after meal:
1. inc BG and insulin: lasting 1-2 hours 2. glycogen synthesis 3. glucose oxidation: for E in other cells 4. adipose in mammals, liver in birds: fat syn (glc--> Ac --> Icfa --> TG) |
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fasting situation
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fasting situation:
- several hours post meal - glc still essential for many cells - low normal glc: stimulates glucagon secretion 1. glycogenolysis 2. lipolysis and gluconeogenesis 3. proteolysis |
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glycogenolysis
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glycogenolysis:
- inc by glucagon, depleted rapidly - hydrolysis of glycogen stores to increase BG |
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lipolysis
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1. lipolysis: mobilization of fat stores to provide E for other tissues
- inc by glucagon and epi - TG --> glycerol + 3 fa's (54C) |
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gluconeogenesis
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gluconeogenesis :
- synthesis of glc from non-carb sources - glycerol from lipolysis can be used |
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proteolysis
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proteolysis:
- breakdown of body proteins 1. ketogenis aa's: good E source - production of ketone bodies= acetone, acetoacetic acid, beta hydroxybutyric acid 2. glucogenic aa: - via gluconeogenesis: gives off NH2 |
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dietary carbs and R
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dietary carbs and R:
- higher in F than NR - more complex carbs 1. non-structural: sugars, starches, fructosans 2. structural: cellulose, hemicellulose, pectins, ligin |
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R carb met
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R carb met:
- all fermented except that bypassed to SI - no salivary but pancreatic amylase - VFA's: main abs end product of fermentation, little glc abs - R and NR cell req same: R constantly undergoing gluconeogenesis in liver |
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R BG homeostasis
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R BG homeostasis:
- low 40-60 mg/dl - less fluctuation than NR: 1. constant eating 2. continuous VFA production 3. continuous digesta flow 4. continuous gluconeogenesis |
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R acetate met
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R acetate met:
- 2 C organic acid: CH3COOH - Ac in rumen--> rumen wall --> portal v --> liver --> gen circulation - Ac used as: 1. E source 2. substrate for fa's 3. meat, milk modification |
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R proprionate met
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R proprionate met:
- 3 C organic acid: CH3CH2COOH - rumen: 1. 85% prop, 15% lactate --> liver --> low prop in blood or glc gen circulation 2. gluconeogenesis sites: liver and kidneys |
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R butyrate met
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R butyrate met:
- 4 C organic acid: CH3(CH2)2COOH - 25% but in p vein, 75% betaBHBA--> liver--> ketones - little butyric acid ends up in gen circ |
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ketones
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ketones:
- sources: rumen wall and liver - 2-3% diff b/w blood and milk 1. E source 2. substrate for fat syn |
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ketosis
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ketosis:
- met dz common in dairy cows soon after calving - early lactation during active lipolysis - hypoglycemia, ketonuria, anorexia, lethargy, depressed milk production |
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carb met R vs NR
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carb met R vs NR:
- not very different 1. R: high CF--> VFA abs --> GNG --> glc, acetate and BHBA in blood 2. NR: high sol carbs--> abs of glc --> BG |
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respiration
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respiration:
1. mobilization of AcCoA: glycolysis, beta oxidation or proteolysis to form ketogenic aa 2. TCA gen H+ 3. e- transport and oxidative phosphorylation: final E acceptor O2, yields 2-3 ATP - CO, H2S and CN can stop ET |
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glycolysis
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glycolysis:
1. monosacc met to triose: glc --> pyruvate --> lactate 2. all cells, cytoplasm 3. E consumed, ATP gained 4. numerous substrates can contribute C 5. begins with phosphorylation (hexokinase) 6. yield 2 ATP/ glc oxidized |
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TCA
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TCA:
1. mitochondria 2. input AcCoA: from activation of acetate from blood or pyruvate from glycolysis: pyruvate + CoA --> AcCoA + CO2 + 2H 3. acetate oxidation: condensation of OAA (4C) with AcCoA (2C) --> citric acid (6C) - BHBA can also be converted to AcCoA 4. output: citric acid oxidized to OAA + 2CO2 + 4H+ + 1 GTP |
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E of glc oxidation and respiration
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E of glc oxidation and respiration:
glc + 6O2 --> 6CO2 + 6H2O + 36ATP - net yield: 36 ATP/ glc - reverse of photosynthesis: 673 kcal solar E--> 36 ATP |
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gluconeogenesis
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gluconeogenesis:
- glc gen from non carb precursors - more continuous in R - kidney, liver only - major precursors: proprionate, lactate, glucogenic aa, glycerol, NOT fa's - glucogenic aa converted to lactate or alpha keto glutarate |
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key enz in hepatocytes
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key enz in hepatocytes:
1. pyruvate carboxylase (PC) converts pyr--> OAA 2. PEP carboxykinase (PEP-CK): rate-limiting enz converting OAA to PEP 3. glc-6-phosphatase: glc-6-P to glc |
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met R vs NR
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met R vs NR:
1. primary E substrate abs from GIT: NR glc and R vfa 2. primary substrate for fat syn: NR glc vs R acetate 3. extent of glc abs from gut: NR extensive vs R little 4. cellular demand for glc: NR and R high 5. importance of gluconeogenesis: NR important (glycerol, aa) vs R very important (proprionate, glycerol, aa) 6. ketone production: NR abnormal (any =ketosis) vs R normal (excessive= ketosis) |
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crossroads in met pathways
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crossroads in met pathways:
1. glc 2. glc-6-P 3. pyruvate 4. acetate 5. AcCoA |
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main gluconeogenesis to-knows
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main gluconeogenesis to-knows:
- main substrates: propionate, lactate, GNG-aa - PEP CK: OAA--> PEP - glc-6-phosphatase: glc-6-P --> PEP - PC: pyruvate--> OAA - OAA <--> malate - 2C: AcCoA - 4C: succinate, fumarate, malate, OAA - 5C: alpha keto glutarate - 6C: citrate, isocitrate |
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carb digestion in R
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carb dig in R:
1. mouth: starch, sol sugars, cellulose, h cellulose --> simple sugars 2. stomach: microbial fermentation, vfa abs, pyr--> acetate, succinate, lactate -->proprionate, butyrate 3. SI: pancreatic amylase, maltose and lactose (calf) 4. intestinal mucosa: maltase and lactase--> glc, gal - with exception of milk-fed calf, relatively little glc abs in GIT |