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BIBC 120 > Week 3 Carbohydrates > Flashcards

Week 3 Carbohydrates Flashcards

1
Q

Liver: Metabolism Mediator

A 
> Detoxification
> AA + FA metabolism
> Urea Cycle
> Gluconeogenesis
> Glycogen synthesis/store
> Alcohol metabolism
> Bile, cholesterol, lipid and blood protein synthesis
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2
Q

Imperatives of Metabolism

A
  1. ATP production (even during fasting)
  2. Maintain blood glucose (5 mM for brain function)
  3. Sources: carbs, FA, AA
  4. Absorption: 1-3 hours after meal (post prandial)
  5. Post-Absorption: FA
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3
Q

Pancreas: Insulin and Glucagon

A
  1. Alpha Cells: secrete glucagon
    > Raises BGL –> Increases breakdown/ glucose synthesis
    > + Epinephrine Increases lipolysis/HSL –> decreases fat storage/ Increases release
  2. Beta Cells: produce insulin (most abundant of islet cells)
    > Lowers BGL –> increases storage/ glycogen synthesis
    > Decreases lipolysis/HSL –> Increases fat storage
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4
Q

Archibald Garrod: Inborn errors of Metabolism

A

Investigation of alkaptonuria
> Single enzyme error and Mendelian inheritance
> Disease: intermediate of aromatic AA metabolism in urine (homogentisic acid buildup)

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5
Q

Asbjorn Folling:

Phenylketouria (PKU)

A

Molecule in urine had an entity that reacted to iron (ketone with aromatic residue)
> PKU deficient: NO L-phenylalanine –> L-tyrosine via phenylalanine hydroxylase (PAH blocked)
> Transamination of phenylalanine –> phenylpyruvate via alpha-keto –> glutamate (PHENYLPYRUVATE BUILDUP –> TOXIC)
> Diet solution: limit phenylalanine (NO ASPARTAME); provide essential tyrosine

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6
Q

Carbohydrates

A
  1. Mono: fructose, glucose, galactose
    > Same structure; either aldehyde/ketones
    > Anomer rings: circular formation due to OH attacking aldehyde group –> hemi-acetal –> alpha and beta forms (linear and ring form oscillating)
  2. Di-: maltose (Glu+Glu), sucrose (Glu+Fruc), Lactose (Glu+Gal)
    > Maltose: alpha 1-4 glycosydic
    > Sucrose: alpha 1-6
    > Lactose: beta 1-4
    **Raffinose: Gal a1-6 Glu a1-4 Fruc (humans have no alpha-galactosidase –> gut bacteria act up)
    **    Beano: enzyme-based dietary supplement to reduce gas (has a-GAL and invertase)
  3. Poly: starch (straight chain amylose/ branched amylopectin), glycogen (muscle and liver), fibers (soluble pectin/ insoluble cellulose)
    > Digestible: a1-4 (starch and glycogen; some a1-6; both have glucose monomers)
    > Undigestible: b1-4 (cellulose made from beta-cellulose monomers)
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7
Q

Glycogen

A

Short term storage supply of glucose
> Human: 450g or enough for 1.5 days (Liver 100g, muscle 400g, brain very little)
>**Liver glycogen: blood-releasable glucose
> **Muscle glycogen: intracellular glucose ONLY

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8
Q

Fibers (not digested by human enzymes)

A
  1. Soluble: pectins, gums, mucilage
    > Dissolves in water –> bacteria fermented in colon to organic acids (butyric: signals to GI track and body)
  2. Insoluble: cellulose and hemicellulose
    > No water dissolving thus poor fermentation
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9
Q

Carbs Digestion Overview

A
  1. Amylase: starch –> maltose
  2. Amylase inactivated by strong acid
  3. Amylase from pancreas: starch –> maltose
  4. SI enzymes: disac –> monosac
  5. Absorbed monosac into blood –> liver
  6. Soluble fiber fermented into acid/gases by LI bacteria
  7. Insoluble fiber in feces; very little carb present
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10
Q

SI glucose absorption: Na+ Glucose Cotransport

A
  1. Apical surface SGLT1 (Sodium Glucose Transporter)
  2. Basal Surface GLUT2 (uniport glucose transport via faciliated diffusion)
    * Muscle absorption of glucose is by ACTION OF INSULIN REGULATED GLUT4 ONLY**
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11
Q

Carbohydrates are Useful Because…

A
  1. Support glycogen reserves in muscles and livers
    > Glycogen amount increases over work time
    > Glucose for brain comes from liver glycogen usually
    > Low glycogen: AA +
    glycerols –> glucose produced
  2. Protect against ketosis and protein loss
    > KETOSIS: Glycogen storage drops and BGL starts dropping –> glucogenesis/glucogenenic AA/Krebs intermediates/FA oxidation powering make glucose –> Acetyl-CoA buildup and ketone bodies form
  3. Provide fibers
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12
Q

Starvation Progression

A
  1. Glycogen gone (24 hrs)
  2. Fat/protein gone (3-4 days)
  3. Slow protein degradation –> lipids become primary fuel –> brain uses ketone bodies
  4. WORST CASE: (prolonged)
    > AA –> TCA intermediates to make glucose (lipids power liver; ketosis high muscle wasting)
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13
Q

Diet: Carb requirements

A
  1. At least 50-100g/d carbs
  2. RDA = 130 g/day for adults
  3. Average consumption is 180-330 g/day in US
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14
Q

Diverticula/Diverticulosus

A

Pockets form in walls of digestive tract
> Inner layer of intestine pushes through weak spots in outer lining –> pouches bulge out in colon
> 50% of 60+ y.o. have this condition
> Fibers: Increase bulk/soften stools; Less elimination pressure/constipation/piles/diverticula

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15
Q

Soluble Fibers + Microbes

A
  1. Binds Glucose –> slow glucose absorption –> lower diabetes risk
  2. Binds cholesterol/biles –> slow abs –> lower CVD risks
  3. Reduce appetites –> lower obesity risks
  4. Feeds colon microbes (fermentation) –> GI track lining and IS nourished –> lower asthma, Crohn’s and inflammation risks
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16
Q

Meta-Analysis

A

Quantitative epidemiological study design
> Assess previous research studies to derive conclusions about topic
> Benefits: consolidated review of a large and potentially conflicting body of literature; more precise estimate of treatment effect/risk factor of disease

17
Q

Aune Study: Dietary Fiber and Breast CA risk

A

Case-Control –> dietary fibers are inversely related to Breast CA risk, but only observed among studies with a large range (13+ g/day) or high level of intake (25+ g/day)

18
Q

Microbial Metabolism of Fibers influence asthma/hematopoiesis

A
  1. Mouse model shows high-fiber diet reduces (Stained) mucus accumulation in lungs
    > Low fiber diet (89% Firmicutes, low Bacteroidetes) increase risks
    > High fiber diet with pectin (52% Firmicutes and 42% bacteroidetes) decrease risks
    > Increase SCFA too to stimulate growth of bifidobacterium and bacteroidetes
19
Q

RDA : Fibers

A
  1. Women: 25g/day
  2. Men: 38g/day
  3. US avg: 14-17g/day
    > Sources: whole plant-based foods; vegetables, beans, whole grains
20
Q

Hyperglycemia

A

125 + mg/dL
> Excessive thirst, hunger and urination (kidney filters and releases glucose in urine –> dehydration)
> Glucagon: increases glycogen breakdown + glucose synthesis (alpha cells)

21
Q

Hypoglycemia

A

50 - mg/dL
> Nervous, irritability, headache (no fuel)
> Insulin: Increases glucose breakdown and glycogen synthesis (Beta cells)

22
Q

Glycemic Index (GI) and Glycemic Load (GL)

A
  1. Changes in BGL caused by 50g of carbs (compared to 50g of glucose)
    > (BGtest/BGgluc)x100
    > 8-10 fasted subjects with 50g carbs monitored for 2-3 hours
    > 55- low (Spaghetti), 55-70 intermediate (New potato), 70+ high (White rice)
  2. (GI/100) x g of carbs
    > 15- low (Carrots), 15-20 intermediate (New potato), 20+ high (Baked beans)
    > High problems: 1. easily hungry (obesity); 2. risk for CHD (women); 3. risk of insulin insensitivity
23
Q

Insulin and Diabetes: Banting and Best

A
  1. Pancreas removal caused diabetes in dogs
  2. B&B: insulin was destroyed by hypothesized enzymes
    > Tie off pancreatic duct –> protease secreting cell death –> extract pancreas and stabilize BG
    > Active signal purified was insulin
24
Q

Type I Diabetes

A

5-10% (juvenile onset)
> Autoimmune loss of beta cells –> insulin-dependent
> Treatment: insulin injection
> Fatality: BGL 40 - mg/dL

25
Q

Type II Diabetes: NIDDM

A

90% (80% obesity)
> Reduced insulin sensitivity
> Treatment: medication and diet/exercise change
> LOW GI and GL will help: does not exceed maximum desirable BGL

26
Q

Diabetes Overview

A
  1. 10% population; 6th leading cause of death
  2. Leading cause of blindness, kidney failure and amputation
  3. Ketosis –> ketoacidosis –> coma and death
27
Q

Sugar Consumption: HFCS (High Fructose Corn Syrup)

A
  1. Decreasing Sucrose, increasing HFCS, and constant corn syrup consumption –> overall increase in total sugar consumption
  2. Top 3 contributors: soft drinks, sugars/candy, and cakes/cookies/pies –> CVD
  3. Cross-section analysis in relation to diabetes
    > Every 150 kcal/person/day increase in sugar increased diabetes by 1.1%
    > Tested for selection biases and controlling fibers/meats/fruits/total calories
28
Q

Artificial Sweetners

A
  1. Sugar Alcohols:
    > Sorbitol, mannitol, xylitol (all nutritive, metabolized to glucose but slowly; 3 kcal/g; not as sweet)
  2. Non-nutritive:
    > Saccharin, aspartame, sucralose (no cal, much sweeter than sucrose)

**Problems:
> Effects may contribute to metabolic syndrome and obesity epidemic, despite alleviation of insulin resistance
> Changes host microbiome –> decreased satiety, altered glucose homeostasis, and increased calorie consumption

BIBC 120 (9 decks)

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