Test 2 Carbohydrates

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Test 2 Carbohydrates
2011-09-25 17:20:12
Carbohydrates sugar reactions

Section 2 Carbohydrate synthesis
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  1. Define glycolysis aka (glucolysis)
    • The catabolism of glucose to form energy:
    • 1. via EMP- aerobic production of ATP:

    glucose is converted to pyruvic acid(pyruvate)and then to CO2 and H2O (ATP)

    2. via HMS- anaerobic production of ATP & NADPH:

    glucose is converted to lactic acid.This pathway is used to produce energy for RBC.

    3. Glucose is the only sugar used for direct energy.
  2. Define gluconeogenesis
    The formation of glucose from amino acids and the glycerol portion of lipids.

    *Occurs with severly decreased blood glucose levels

    *When blood glucose levels fall after gycogen stores are used up...starvation
  3. Define glycogenolysis
    the breakdown of gylcogen to form glucose
  4. Define glycogenesis
    glucose is converted to glycogen and stored in the liver and muscles
  5. Define lipogensis
    glucose that is converted to trigycerides(fat) and is stored in adipose tissue
  6. Define lipolysis
    the breakdown of trigycerides to form glucose

    *amino acids are used up then muscles breakdown

    * ketones are a waste product of this process
  7. Define EMP Pathway
    Emden Meyerhof Pathway is the pathway for aerobic ATP production

    pyruvic acid to pyruvate then to CO2and H2O
  8. Define HMS Pathway
    Hexose Monophosphate Shunt- the anaerobic production of ATP & NADPH

    glucose to lactic acid

    • used for RBC energy production
    • glucose is the only sugar used directly for energy production
  9. Define amylase
    An enzyme found in saliva which begins the digestive process
  10. Define Oligosachharides
    • sugars that yield 2- 6 molecules of simple sugars
    • Disachharides are the most common oligosachharide with 2 molecules of sugar
    • If aldehyde or ketone group of one molecule bonds with the alcohol group of the other=reducing sugar
    • If Aldehyde or ketone group of one sugar bonds with an aldehyde or ketone of the other molecule joins=non reducing sugar

    • Maltose- glucose + glucose= reducing
    • Lactose- glucose + galactose= reducing
    • Sucrose- glucose + fructose= non reducing
  11. Define monosachharide
    sugars and starches in theor simplest form.

    *Monosachharides consist of 3-8 carbons plus 1 aldehyde (H-C-=O) or 1 ketone (H-C-OH)

    • Most common monoschharides in living orgaisms are hexoses:
    • 1. glucose(dextrose) - reducing
    • 2. Fructose- reducing
    • 3. Galactose- reducing
  12. Define polysachharide
    100- many thousands of sugar molecules combined

    Types of polysachharides:

    1. Glycogen- animal fat stored in muscle cells and liver

    2. Starch- storage product for plants

    3. Cellulose- insoluable plant polysachharide not digested by humans
  13. Define glycogen
    animal fat stored in muscle cells and liver for short term energy
  14. Define glycosuria
    occurs when the blood glucose concentration is above the renal threshold of 160-180 mg/dL and the excess glucose spills into the urine
  15. Define insulin
    the body's only hypoglycemic agent.

    • 1. It is produced by the beta cells in the Islets of Langerhans of the pancreas-
    • Proinsulin to Insulin + C-peptide

    2. It promotes glycogenesis & lipogenesis

    3.It makes a cell permeable to glucose & allows glucose to be absorbed in the cell, also promotes glycogenesis (storage) in liver
  16. Define C-peptide
    produced by the beta cells of the Islets of Langerhans in the pancreas, it accompanies insulin production, and c-peptide levels correlate with insulin levels, unless increased insulin levels are due to overdose of insulin medication.
  17. Define IDDM
    Insulin dependant diabetes mellitus also known as Type I diabetes- is caused by a decrease or lack of insulin produced in the body.
  18. Define NIDDM
    Non insulin dependant diabetes mellitus-Also known as Type II diabetes- caused by normal or increased production of insulin, but the body is less sensitive to the insulin that is produced, and does not respond to the insulin correctly.
  19. Define hypoglycemia
    • decreased blood glucose concentration-
    • anxiety,shaking, sweating
    • fasting hypoglycemia is very serious but post prandial (reactive) is usually not serious. Diagnosed with a blood glocose level of < 50 mg/dL
  20. Define hyperglycemia
    elevated blood glucose concentration caused by decreased or lack of insulin production (Type I diabetes)or nonfunctional insulin (Type II diabetes)
  21. Define glucagon
    a hyperglycemic agent that increases blood glucose concentrations.It is synthesized by the alpha cells in pancreas, increases glycogenolysis and gluconeogensis( tells liver to make glucose & produces it from other sources)It also inhibits glycolysis. Insulin goes down when glucogon goes up.- they work against each other
  22. Define polyuria
    Increased urination
  23. Define polydypsia
    Increased thirst
  24. Define ketones
    They are a waste product formed from lipolysis( breakdown of triglycerides to form glucose)
  25. Define ketoacidosis
    acidosis due to an excess of ketone bodies, occurs in individuals that do not produce enough insulin to support normal fat metabolism
  26. Define microalbumin
    tiny amounts of albumin in the urine, too little to be detected by the standard dipstick tests. 30-300 mg of albumin in a 24 hr urine; or a spot urine test with albumin to creatinine ratio of 30 to 300
  27. Normal serum or plasma glucose ranges
    • random : 70-150 mg/dL
    • (3.9-8.3 mmol/L)

    • fasting: 70-99 mg/dL
    • ( 3.9-6.0 mmol/L)
  28. Normal glucose range for CSF
    • 60% or 2/3 of plasma and serum levels
    • 40-80 mg/dL adult
    • (3.8-5.5 mmol/L)
  29. Normal glucose range for capillary whole blood
    15% lower than plasma or serum

    • 60-84 mg/dL
    • (3.3-4.6 mmol/L)
  30. normal adult glucose 2 hr post prandial
    • 70-150 mg/dL or slightly less
    • (3.9- -8.3 mmol/L)
  31. Define hexokinase
    • an enzyme present in cells that in the presence of ATP will catalize the conversion of glucose to glucose -6- phosphate; this is the first step in glycolysis
    • It is also an enzymatic method to detects glucose by measuring NADPH levels
  32. Define glucose oxidase
    a glucose enzyme- also an enzymatic method to detect glucose by measuring hydrogen peroxide's electric potential(oxygen consumption method) or the color intensity of dyed hydrogen peroxide (Trinder method)
  33. Define hemoglobin A1C
    • it is one of glycosolated hemoglobins, and the only one which can be measured.This value is used to monitor long term maintenance of diabetic patients. RBC are permeable to glucose...the hemoglobin attaches to the glucose and then it is called "glycosolated"
    • there are 4:
    • A1a1
    • A1a2
    • A1b
    • A1c- this is only one that can be measured- normal is 4-6%
  34. Explain the historic oxidation-reduction of heavy metals testing methods.
    • a reducing element(sugars and biological substances) react in a oxidation-reduction reaction to reduce heavy metals(copper,iron,etc) to a lower ionic value.It reduces the valence of heavy metals.
    • This is the basis of the Modified Benedicts Reaction used today as the clinitest tablet for semi-quantitative measurement of reducing sugars in urine sample.
    • The reaction:
    • CU++ + reducing sugars(in urine sample)(heat +OH)-->
    • CU2O(red) + CuOH(yellow)
    • Sugars measured: all reducing sugars

    Specimen used: Urine only

    What is actually being measured: red & yellow precipitates

    Pass thru is a possibility on this test
  35. Explain the historic Aromatic Amine Reaction of glucose analysis
    • o-Toluidine + Glucose ---------->
    • Glycosamine (colored)

    First stat method used.

    Sugars measured: all reducing sugars

    Specimen used: plasma, serum

    What is actually being measured: colored gycosamine (proportionally)
  36. Name this reaction

    o-Toluidine + Glucose ---->
    Glycosamine (colored)
    Aromatic Amine Reaction
  37. Name this reaction

    CU++ + reducing sugars(in urine sample)(heat +OH)-->CU2O(red) + CuOH(yellow)
    Oxidation Reduction Reaction
  38. Explain the enzymatic Hexokinase Method of glucose detection
    Enzymes that are specific to glucose are used as reagents for the reaction;

    • (HK)+G-6-PD-->Glucose 6 Phosphate+ ADP G-6-P + NADP+ + G-6-PD--->
    • 6 Phosphoglutonate + NADPH + H+

    Sugars measured: glucose

    Specimen used: any-urine,serum,body fluid,CSF,plasma

    What is actually being measured: NADPH+ -- it is directly proportional to glucose- it absorbs UV light at 340 nm...NADP does not absorb UV light
  39. Name this reaction:

    (HK)+G-6-PD-->Glucose 6 Phosphate+ ADP G-6-P + NADP+ + G-6-PD--->6 Phosphoglutonate + NADPH + H+
    Hexokinase Reaction
  40. Explain the glucose oxidase Oxygen Consumption Method of glucose detection
    • Glucose oxidase + Glucose+ O2---->
    • Gluconic Acid + H2O2
    • H2O2 is consumed in the potentiometic reading

    Sugars measured: glucose only

    Specimen used: any except urine

    What is actually being measured: the electrical potential of hydrogen peroxide...using ion specific electrodes
  41. Name this reaction:

    Glucose oxidase + Glucose+ O2---->Gluconic Acid + H2O2H2O2 is consumed in the potentiometic reading
    Oxygen Consumption Method of glucose detection
  42. Explain the glucose oxidase Trinder method of glucose detection
    • Glucose Oxidase + Glucose + O2 ---->
    • Gluconic Acid + H2O2
    • H2O2 + dye + horseradish peroxidase(enzyme) ----> dye + H2O

    It colors the hydrogen peroxide directly proportional to the glucose level

    Sugars measured: glucose only

    Specimen used: all

    What is actually being measured: the color of the hydrogen peroxide which is directly proportional to the glucose level using a spectrophotometer
  43. Name this reaction:

    Glucose Oxidase + Glucose + O2 ----> Gluconic Acid + H2O2 H2O2 + dye + horseradish peroxidase(enzyme) ----> dye + H2O
    The Trinder glucose oxidase method
  44. Name 6 substances that increase blood glucose concentrations
    1. Glucagon - synthesized by the Alpha cells of Pancreas- inhibits gycolosis

    2.Growth Hormone (GH) and ACTH-produced by pituitary, blocks action of insulin and glucagon, stabilizes glucose levels

    • 3. Steroids- manufactured from cholesterol,
    • Cushing's Syndrome-increased
    • steroid and glucose levels
    • Addison's Disease- decreased steroid and glucose levels

    • 4. Epinephrine- secreted by the adrenal gland another name for adrenaline "fight or flight"
    • stimulates glycogenolysis,gluconeogenesis and lipolysis

    5. Thyroxine (T4)- secreted by thyroid gland stimulates glycogenolysis and depletes liver of glycogen

    6. Cortisol-produced by adrenal cortex , antagonistic to insulin, promotes gluconeogenesis
  45. Name the three types of carbohydrates
    • Monosachharides
    • Oligosachharides
    • Polysachharides
  46. What is the renal threshold for glucose
    160-180 mg/dL of blood concentration
  47. Which sugar is used directly for energy?
  48. Ketones are a waste product of what process?
    lipolysis- breakdown of triglycerides to form glucose
  49. Explain carbohydrate metabolism, step by step
    1. amylase (enzyme) breaks down some starch and glycogen in saliva

    2. high PH in stomach inhibits amylase- no digestion takes place in the stomach

    3. Pancreatic enzymes(including pancreatic amylase) complete digestion at the microvilli in the small intestines

    4.After absorption into the blood, all sugars are transported to the liver via the hepatic portal system

    5. 40% is released directly into the blood stream & is immediately metabolized in the mitochondria of each cell for energy; this causes a natural rise in blood sugar levels 1/2 hour later.

    • 6. The other 60 %- some is stored in the liver and muscles as glycogen;
    • some is converted to ketoacids , amino acids, and proteins; some is converted to fat (trigycerides) and is stored in adipose tissue.
  50. Normal glucose concentration for urine
    negative < 30 mg/dL
  51. Normal glucose 2 hr level on glucose tolerance test
    should be normal or slightly below normal
  52. Conversion formula for mg/dL to mmol/L
    mg/dL x 10 divided by 180 (molecular weight of glucose) = mmol/L
  53. what are the specimens of choice for blood glucose testing?
    nonhemolyzed serum or heparinized plasma

    serum must be removed from cells immediately/ glucose levels drop 7% per hour/ they are utilized by the cells

    Glucose is stable at RT for 8 hrs, 72 hrs at 4 C
  54. Which blood tubes are used for glucose testing collection? Explain specimen handling.
    Usual are red,gold,gray tiger top;

    or solid gray which contains sodium fluoride /recommended when plasma can't be separated with 1 hr, NaFl interferes with other enzymatic testing procedures

    Capillary blood must be analyzed immediately, cannot be stored, and it MUST be noted that is a capillary sample as levels are 15% lower than normal

    CSF must be analyzed immediately after being centrifuged

    Random urine stable 24 hrs with refrigeration, must be brought back to RT before testing

    24 hr urine must be preserved with glacial acetic acid or sodium benzoate