Carbohydrates

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1

lipogenesis

the conversion of carbohydrates to fatty acids

2

lipolysis

the decomposition of fats

3

carbohydrates

the major food source and energy supply for the body stored primarily in the liver and muscle glycogen; compounds containing Carbon, Hydrogen, and Oxygen; classified according to the number of sugar units in the chain

4

trioses

carbohydrates containing three carbons

5

Fisher projection

model of a carbohydrate that has the aldehyde or ketone at the top of the drawing

6

Haworth projection

represents the compound in the cyclic form that is more representative of the actual structure

7

Monosaccharides

simple sugars that cannot be hydrolyzed to a simpler form; can contain three, four, five, or six or more carbons atoms; most common are glucose, fructose, and galactose

8

Disaccharides

formed when two monosaccharides are joined by a glycosidic linkage, covalently bonded with the loss of a water molecule; split into two monosaccharides by enzymes (such as lactase) located on the microvilli of the intestine; most common are maltose, lactose, and sucrose

9

Oligosaccharides

the chaining of 2 to 10 sugar units

10

Polysaccharides

formed by the linkage of many monosaccharide units; usually insoluble in water

11

D-glucose

Aldoses having an aldehyde group at one end

12

D-fructose

ketoses having a keto group usually at C2

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D isomers

most naturally occurring sugars

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lactose

milk sugar composed of galactose and glucose

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sucrose

common table sugar composed of glucose and fructose linked by their anomeric hydroxyls and a glycosidic bond

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maltose

two glucose molecules

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starch

the main storage form of carbon in plant cells

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glycogen

the main storage form of carbon in animal cells; digests to maltose

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salivary amylase

hydrolyzes starch to dextrin and maltose

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pancreatic amylase

aids further digestion of starches and glycogen (to maltose) in the small intestine

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hepatic enzymes

enzymes that convert galactose and fructose to glucose in the liver after monosaccharides are absorbed into the blood stream

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jejunum villi

aid in intestinal absorption of carbohydrates

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microvilli

...

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increased glucose

reasons glycogenesis and glycolysis occur

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decreased glucose

reasons glycogenolysis and gluconeogenesis

26

glycogenesis

the conversion of glucose to glycogen for storage that often occurs after a heavy meal; glucose --->glycogen (liver, muscle)

27

glycolysis

metabolizing glucose to produce pyruvate or lactate and releasing energy; one mole of glucose is broken down to 2 molecules of pyruvate resulting in the net production of 2 ATP; glucose ---> CO2 + H2O +ATP

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glycogenolysis

involves the breakdown of glycogen to form glucose and other intermediate products and is the process that regulates glucose levels between meals; glycogen ---> glucose

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gluconeogenesis

the formation of glucose from noncarbohydrate sources such as amino acids, glycerol, or lactate that occurs during long-term fasting; non-CHO sources ---> glucose

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>160-180 mg/dL

renal threshold for glucose

31

Insulin

secreted by the beta cells of the pancreatic Islet of Langerhans; produced in response to elevated blood glucose levels; the only hormone that acts to lower blood glucose (promotes glucose uptake by cells, induces glycogen storage in the liver, inhibits lipolysis, increases protein synthesis from amino acids, and enhances glycolysis

32

glucagon

secreted by the alpha cells of the pancreatic Islet of Langerhans; responds to a low blood glucose level; primary hormone to produce a rapid increase in blood glucose; stimulates glycogenolysis and gluconeogenesis; increases the release of fatty acids from adipose tissue

33

epinephrine (adrenaline)

secreted by the adrenal medulla; increases glucose levels by stimulating glycogenolysis and inhibiting insulin secretion; released in response to stress

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thyroxine (t4)

secreted by the thyroid gland to promote glycogenolysis

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cortisol

secreted by adrenal cortex to stimulate gluconeogenesis

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adrenocorticotropic hormone ACTH

secreted by anterior pituitary to stimulate cortisol production

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growth hormone

secreted by anterior pituitary to inhibit glucose uptake by tissues and stimulate liver glycogenolysis

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whole blood

used with waived or home glucose monitoring methods

39

NaF

preserves glucose for 24 hours; cannot be used for enzyme assays

40

+5mg/dL

capillary blood fasting glucose difference

41

10-15% higher

plasma/serum blood glucose difference from whole blood

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70-110 mg/dL

reference range for plasma or serum glucose level

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40-70 mg/dL

CSF glucose reference range

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60-70%

percentage of plasma glucose expected from CSF sample

45

<500 mg/dL

expected glucose levels for 24 hr urine

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none

expected glucose levels for random urine

47

glucose oxidase test

oxidizes glucose to gluconate and hydrogen peroxide; produces quinoneimine dye measured at 500nm; absorbance is proportional to concentration of glucose in the sample

48

hexokinase testing method

catalyzes the phosphorylation of glucose by ATP producing ADP and glucose-6-phosphate

49

glucose-6-phosphate

oxidized to 6-phosphogluconate with reduction of NAD+ to NADH by G-6-PDH; amount of NADH formed is proportional to the concentration of glucose in the sample and can be measured by the increase in absorbance at 340nm

50

7%

rate at which glucose levels decrease per hour testing or separation of cells from whole blood is delayed

51

ABO Blood Marker

found on red blood cells made up of carbohydrates; allow us to distinguish our body's blood type from a foreign blood type

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carbohydrates in body

prevent blood clots and are found in genetic material

53

hyperglycemia

increase in plasma glucose levels due to hormone imbalance; glucose >110mg/dL

54

diabetes mellitus

a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin inaction, or both

55

Type I Diabetes

insulin-dependent diabetes; results from cellular-mediated autoimmune destruction of pancreatic B cells causing absolute deficiency of insulin; absence of insulin with excess glucagon; islet-cell antibodies usually present; 10-20% of diabetes cases; Non-Hispanic Whites and Blacks

56

Signs and Symptoms Type I

polydipsia (thirst), polyphasia (hunger), polyuria, rapid weight loss, hyperventilation, mental confusion

57

Complications Type I

diabetic ketoacidosis, nephropathy, neuropathy, retinopathy, increase in heart disease, blindness, and gangrene

58

ketones

complication of uncontrolled diabetes mellitus; produced from fats, especially in Type I; causes acid-base imbalance acidic blood leading to DKA; acetone, acetoacetate, B-hydroxybutyrate

59

Lab Findings Type I

decreased insulin, increased glucagon (stimulates gluconeogenesis and lipolysis), ketoacidosis, decreased blood pH, low sodium and CO2 levels with increased potassium levels

60

Type II Diabetes Demographics

most common form; adult onset (usually >40) more common in American Indians and non-Hispanic blacks; milder signs and symptoms; raising incidence

61

Type II Diabetes Mellitus

Non-Insulin-dependent diabetes mellitus; develops gradually; caused by insulin resistance and relative deficiency; plasma glucose is unable to enter cells; caused by obesity, lack of exercise, diet, genetics, drugs (diuretics), and increases in hormones that inhibit or antagonize insulin

62

Lab Findings Type II

Hyperglycemia, glycosuria, insulin is present, glucagon not elevated; nolipolysis or ketoacidosis, increased triglycerides (excess glucose converted to triglycerides), normal or increased Na and K, increased BUN and creatinine due to decreased renal function, hyperosmolar plasma from hyperglycemia

63

70-99 mg/dL

NDA normal fasting glucose result

64

100-125 mg/dL

NDA pre-diabetes fasting glucose result

65

126 and above

NDA diabetes mellitus diagnosis from fasting glucose result

66

Diabetes Mellitus Diagnosis

Any two tests on different days; random or non-fasting plasma glucose >200 mg/dL, fasting plasma glucose >126 mg/dL, and 2hr Post prandial glucose >200 mg/dL after 75g glucose load

67

glucose tolerance

post load glucose level when patient is given a 75g glucose drink and glucose is drawn two hours later; glucose over 200mg/dL indicates diabetes

68

glycated hemoglobin A1C

irreversible reaction occurring throughout RBC lifespan; reflects timed glucose average over previous 4-8 weeks; equals 80% total glycohemoglobin

69

3-6%

reference range of A1C to total Hgb

70

12-20%

A1C diagnostic of uncontrolled diabetes mellitus to total Hgb

71

9-12%

A1C indicating controlled diabetes mellitus to total Hgb

72

35%

reduction in microvascular complications for every 1% decreased in HbA1c

73

gestational diabetes

screening performed at 24-28 weeks gestation; GTT fasting blood and urine, drink 100 g glucose load within 5 minutes, only water after, specimens at 1, 2, and 3 hours

74

>140 mg/dL

diagnostic of gestational diabetes one hour after 50-g glucose load screening

75

gestational diabetes complications

can cause increased incidence of congenital malformations and perinatal mortality along with an increased risk of the mother acquiring diabetes in later years

76

hypoglycemia

plasma glucose below 60 mg/dL; glucagon released to inhibit insulin; epinephrine, cortisol, and growth hormone released from adrenal glands to increase glucose metabolism and inhibit insulin

77

60mg/dL

plasma glucose levels indicating hypoglycemia

78

hypoglycemia symptoms

increased hunger, sweating, nausea, vomiting, dizziness, shaking, blurred speech and sight, and mental confusion

79

hypoglycemia reactive causes

insulin overdose in diabetics and ethanol ingestion

80

hypoglycemia fasting causes

insulin-producing tumors, hepatic dysfunction, and sepsis

81

lactose intolerance

deficiency of lactase enzyme that metabolizes lactose; abdominal discomfort, cramps, and diarrhea after milk products ingested; diagnosed after GTT baseline day one, lactose instead of glucose on day two, normal curve is normal, abnormal flat curve and pain indicate diagnosis

82

Cushing's Syndrome

not a type of diabetes, but a cause of hyperglycemia; hypercortisolism where hyper secretion of cortisol from adrenal cortex occurs; hyperglycemia occurs because cortisol stimulates gluconeogenesis and is an insulin antagonist

83

galactosemia

congenital deficiency of one or three enzymes involved in galactose metabolism, resulting in increased levels of galactose in plasma; failure to thrive in infants; untreated leads to mental retardation and cataracts; perform Clinitest in urinalysis on patients less than 2 used to detect increased levels of reducing substances (galactose) in urine

84

glycogen storage diseases

inability to metabolize glucose is usually caused by some enzyme deficiency; most common is Von-Gierke's (hereditary glucose-6-phosphatase deficiency); severe hypoglycemia due to inhibited glycogen to glucose breakdown; an accumulation of glycogen in the liver will result in hepatomegaly