Carbohydrates & Metabolism Flashcards

1
Q

The two forms of carbohydrates are ___ and ___.

A

aldose; ketose.

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2
Q

Determine the following structure.

A

Ketose (ketone).

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3
Q

Determine the following structure.

A

Aldose (aldehyde).

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4
Q

Define stereoisomers.

A

The same order and types of bonds but different spatial arrangements and different properties.

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5
Q

Define enantiomers.

A

Images that cannot be overlapped and are nonsuperimposable.

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6
Q

Determine the following structure.

A

D-Glucose.

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7
Q

Determine the following structure.

A

L-Glucose.

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8
Q

What are the common monosaccharides?

A

Glucose, fructose, and galactose.

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9
Q

What are the common disaccharides?

A

Lactose and sucrose.

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10
Q

What are the common polysaccharides?

A

Starch (glucose molecules) and glycogen.

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11
Q

What does it mean for a carbohydrate to be described as a reducing substance?

A

Carbohydrates that can reduce other compounds.

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12
Q

To be considered a reducing substance, the carbohydrate must contain a ___ or an ___ group.

A

ketone; aldehyde.

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13
Q

(T/F) Carbohydrates can form glycosidic bonds with only other carbohydrates.

A

False, they can form glycosidic bonds with carbohydrates and noncarbohydrates.

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14
Q

Nonreducing carbohydrates are lacking what structure?

A

Active ketone or aldehyde group.

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15
Q

What is the most common nonreducing sugar?

A

Sucrose - table sugar.

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16
Q

The nervous system, including the brain, totally depends on which energy source for energy?

A

Glucose.

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17
Q

What occurs when the concentration of glucose falls below a certain level within extracellular fluid?

A

The nervous tissue loses the primary energy source and is incapable of maintaining normal function.

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18
Q

Which enzyme is responsible for the digestion of nonabsorbable polymers to dextrins and disaccharides?

A

Salivary and pancreatic amylase.

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19
Q

Glucose is the only carbohydrate to be directly used for energy or stored as what?

A

Glycogen.

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20
Q

The ultimate goal of the cell is to convert glucose to what?

A

Carbon dioxide and water.

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21
Q

The first step for all pathways of energy synthesis requires glucose to be converted to what?

A

Glucose-6-phosphate.

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22
Q

Glucose-6-phosphate can enter which two pathways to be converted to energy from glucose?

A

Embden-Meyerhof Pathway or the hexose monophosphate pathway (HMP).

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23
Q

Describe the Embden-Meyerhof pathway.

A

Glucose is broken down into two- and three-carbon molecules of pyruvic acid that can enter the TCA cycle on conversion to acetyl-CoA.

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24
Q

Describe gluconeogenesis.

A

The conversion of amino acids by the liver and kidneys to substrates that can be converted to glucose. Encompasses the conversion of glycerol, lactate, and pyruvate to glucose.

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25
Q

In glycolysis, tissues can derive ___ from ___ in an oxygen-deficient environment by converting pyruvic acid into ___ acid.

A

ATP; glucose; lactic.

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26
Q

For anaerobic glycolysis to occur, how many moles of ATP must be consumed for each mole of glucose?

A

2 moles.

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27
Q

Describe the energy pathway HMP shunt.

A

A detour of glucose-6-phosphate from the glycolytic pathway to become 6-phosphogluconic acid.

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28
Q

___ is important to erythrocytes that lack mitochondria and are therefore incapable of the TCA cycle.

A

NADPH.

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29
Q

HMP shunt also permits ___, such as ribose, to enter the glycolytic pathway.

A

pentoses.

30
Q

Describe glycogenesis.

A

The conversion of glucose-6-phosphate to glycogen by glycogen synthase.

31
Q

Which primary tissues are capable of the synthesis of glycogen?

A

Liver and muscles.

32
Q

Describe glycogenolysis.

A

The process of converting glycogen back to glucose-6-phosphate for entry into the glycolytic pathway.

33
Q

What is the result if lipolysis of triglycerides is unregulated?

A

The formation of ketone bodies, which the brain can use as a source of energy.

34
Q

What organs are responsible for keeping blood glucose within a narrow range?

A

Liver and pancreas.

35
Q

During a brief fast (<24 hours), what mechanism is used to supply glucose to the ECF?

A

Glycogenolysis.

36
Q

During a fasting period (>24 hours) what mechanism is used to supply glucose to the ECF?

A

Gluconeogenesis.

37
Q

Control of blood glucose is under which two major hormones?

A

Insulin and glucagon.

38
Q

Where is insulin synthesized?

A

By the beta-cells of islets of Langerhans in the pancreas.

39
Q

When beta-cells detect an increase in body glucose, they release what hormone?

A

Insulin.

40
Q

What is the action of insulin?

A

Increases glycogenesis and glycolysis.

41
Q

What is the primary hormone responsible for increasing glucose levels.

A

Glucagon.

42
Q

Where is glucagon synthesized?

A

By the alpha-cells of islets of Langerhans in the pancreas.

43
Q

Glucagon acts by increasing plasma glucose levels by which mechanisms?

A

Glycogenolysis and gluconeogenesis.

44
Q

Which two hormones produced by the adrenal glands affect carbohydrate metabolism?

A

Epinephrine and glucocorticoids (cortisol).

45
Q

How does epinephrine increase plasma glucose?

A

By inhibiting insulin secretion, increasing glycogenolysis, and promoting lipolysis.

46
Q

How does cortisol increase plasma glucose?

A

By decreasing intestinal entry into the cell and increasing gluconeogeneisis, liver glycogen, and lipolysis.

47
Q

Which two anterior pituitary hormones promote increased plasma glucose?

A

Growth hormone and ACTH.

48
Q

How does growth hormone increase plasma glucose?

A

By decreasing the entry of glucose into the cells and increasing glycolysis.

49
Q

Decreased levels of cortisol stimulate the anterior pituitary to release ____.

A

ACTH.

50
Q

ACTH stimulates the ___ ___ to release ___ and increases plasma glucose levels by converting liver ___ to glucose and promoting gluconeogenesis.

A

adrenal cortex; cortisol; glycogen.

51
Q

The thyroid gland is stimulated by the production of TSH to release ___ that increases plasma glucose levels by increasing ___.

A

thyroxine; glycogenolysis.

52
Q

Somatostatin, produced by the delta-cells in the islets of Langerhans of the pancreas, increases plasma glucose by the inhibition of which hormones?

A

Insulin, glucagon, and growth hormone.

53
Q

Define diabetes mellitus.

A

A group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both.

54
Q

How is Type 1 diabetes characterized?

A

Inappropriate hyperglycemia primarily a result of pancreatic islet beta-cell destruction and a tendency to ketoacidosis.

55
Q

How is Type 2 diabetes characterized?

A

Hyperglycemia cases that result from insulin resistance with an insulin secretory defect.

56
Q

How is impaired fasting glucose characterized?

A

The fasting glucose is increased above normal limits but not to the level of diabetes.

57
Q

How is impaired glucose tolerance characterized?

A

To indicate glucose tolerance values above normal but below diabetes levels.

58
Q

How is Type 1 diabetes mellitus characterized?

A

As a result of cellular-mediated autoimmune destruction of the beta-cells of the pancreas, causing an absolute deficiency of insulin secretion.

59
Q

What are some signs of type 1 diabetes mellitus?

A

Polydipsia (↑ thirst), polyphagia (↑ food intake), polyuria (↑ urine production), weight loss, hyperventilation, mental confusion, and loss of consciousness.

60
Q

How is Type 2 diabetes mellitus characterized?

A

By hyperglycemia as a result of an individual’s resistance to insulin with an insulin secretory defect.

61
Q

How is gestational diabetes mellitus characterized?

A

As any degree of glucose intolerance with onset or first recognition during pregnancy.

62
Q

What are the four diagnostic criteria for DM?

A

(1) HbA1C >= 6.5%
(2) Fasting glucose >= 126 mg/dL
(3) 2h plasma glucose >= 200mg/dL during an oral glucose tolerance test.
(4) Random plasma glucose >= 200mg/dL plus symptoms of DM.

Each of which should be confirmed on a subsequent day by any one of the first three methods.

63
Q

Glucosuria can occur when the glucose concentration of plasma exceeds roughly ___ mg/dL.

A

180.

64
Q

Which type of diabetes is more likely to produce ketones?

A

Type 1 diabetes.

65
Q

Fatty acid oxidation is inhibited in which type of diabetes?

A

Type 2.

66
Q

In type 1, there is an absence of insulin with an excess of glucagon. This permits ___ and ___ to occur.

A

gluconeogenesis; lipolysis.

67
Q

The laboratory findings of a patient with diabetes with ketoacidosis tend to reflect what?

A

Dehydration, electrolyte disturbances, and acidosis.

68
Q

What are the three products produced from the oxidation of fatty acids?

A

Acetoacetate, beta-hydroxybutyrate, and acetone.

69
Q

How is carbon dioxide effected by ketoacidosis?

A

Decreased due to Kussmaul-Kien respiration (deep respirations).

70
Q

Reference range of normal fasting glucose.

A

70-99 mg/dL.

71
Q

Reference range of normal glucose tolerance.

A

2h plasma glucose <= 140 mg/dL.