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Carbohyrdrates and Microbiology :) > Glucose > Flashcards

Glucose Flashcards

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1
Q

Where does energy come from?

A
  • From the oxidation of organic compounds (CHO’s, amino acids, lipids)
  • CHO’s are major source from food
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2
Q

What are the 4 classifications of CHO’s?

A
  1. Size of base carbon chain
  2. Stereochemistry (3D arrangement)
    - “D” or “L” configurations (most human sugars are “D”)
  3. Location of C=O functional group
  4. # of sugar units
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3
Q

Classification of # of sugars

A
  • Disaccharides (2 sugar units)
  • Oligosaccharides (2-10 sugar units)
  • Polysaccharides (>10 sugar units; most common is starch)
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4
Q

Describe reducing substances

A
  • They must contain a free/active ketone or aldehyde groups
  • All monosaccharides and many disaccharides
  • Non-reducing sugar: sucrose
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5
Q

What is the chemical formula and molecular weight of glucose?

A
  • C6H12O6

- MW= 180g

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6
Q

Where does glucose come from?

A
  • Breakdown of CHO’s from diet
  • Body stores (glycogen)
  • Endogenous synth (fr. proteins, lipids)
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7
Q

How does glucose metabolism work?

A
  • Most ingested CHO’s are polymers that cannot be absorbed

- Salivary and pancreatic amylase digests disaccharides

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8
Q

How/where are CHO’s digested?

A
  • Intestinal mucosa (Maltase-glucose; sucrase-glucose+fructose; lactase- glucose+galactose)
  • Mono’s absorbed by gut, hepatic portal vein supplies liver
  • Glucose (β-D-gluc.) is only CHO used for energy or stored as glycogen.
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9
Q

How is glucose metabolized?

A
  • Body converts gluc to CO2+H2O to produce ATP
  • 1st step; use ATP and hexokinase to convert gluc in the cell to G6P
  • Metabolized in 3 pathways
    1. Embden-Meyerhof
    2. Hexose monophosphate shunt
    3. Glycogenesis
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10
Q

Describe the Embden-Meyerhof pathway

A
  • Principle path for gluc oxidation
  • Aerobic: glycolysis produces pyruvate = 2ATP in cytosol
  • Anaerobic: pyruvic acid goes to lactate (glycolysis)
  • Substrates other than gluc can enter this pathway (lipids and proteins)
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11
Q

What is gluconeogenesis?

A

The formation of substrates that can be converted to glucose from non-CHO sources

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12
Q

What is glycolysis?

A

The metabolism of gluc to pyruvate or lactate for energy production
- Anaerobic energy production less efficient

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13
Q

What is lipogenesis?

A

Conversion of CHO’s to fatty acids

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14
Q

Describe the hexose monophosphate shunt

A
  • G6P detours from glycolytic pathway
  • Allows pentoses to enter glycolytic path
  • Resulting NADPH has reducing power- protects RBC’s from oxidative and free radical damage
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15
Q

Describe glycogenesis pathway

A
  • In several tissues, mostly liver and muscles
  • Liver synths G6P from glycogen to glycolytic path
  • Liver also converts G6P to glucose via G6-phosphatase to maintain gluc level in bloodstream
  • Muscle cells; no G6P, gluc only catabolized to G6P or stored as glycogen
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16
Q

What is the body’s response to a low plasma glucose?

A
  • Liver uses; glycogenolysis (glycogen broken down into gluc), gluconeogenesis (gluc generated from non-CHO’s)
  • During short fast: glycogenolysis from liver
  • Fast>1 day: gluconeogensis (lowers glycogen stores)
17
Q

What is/does insulin do?

A
  • From β cells of islet of Langerhans
  • Only released with plasma gluc is increased (hypoglycemic agent)
  • Increases movement of gluc into tissue cells
  • Increases glycogenesis, lipogenesis and glycolysis
    Inhibits glycogenolysis
18
Q

What is/does glucagon do?

A
  • Primary hperglycemic agent
  • From α cells of islet
  • Released during stress and fasting
  • Increases plasma gluc via glycogenolysis in liver and gluconeogenesis
19
Q

What other hormones increase plasma glucose?

From adrenal gland

A

Epinephrine (fr. medulla)
- Released in stress, inhibits insulin secretion, promotes lipolysis

Cortisol (glucocorticoid)
- Stimulated by ATCH and stress, conserves energy for the brain

20
Q

What other hormones increase plasma glucose?

From anterior pituitary

A

GH (Growth hormone)
- Released due to decreased blood gluc/inhibited when increased, decreases gluc entry to cells (anti-insulin), increases lipolysis and hepatic gluconeogenesis

ACTH (adrenocorticotropic hormone)
- Released due to decreased blood cortisol, stims cortisol realease

21
Q

What other hormones increase plasma glucose?

Thyroid gland

A

TSH (pituitary)

  • Stimulates thyroxine (T4) release
  • glycogenolysis, gluconeogenesis, increases intestinal absorption of gluc
22
Q

What other hormones increase plasma glucose?

Pancreas

A

Somatostatin (inhibits gastric secretion and somatotropin release)

  • From δ cells of islet
  • Inhibits insulin, TSH, glucagon and GH
23
Q

Glucose reference ranges

A

Blood:
AC: 3.9-5.5
R: 3.9-11.0
Critical: ≤2.5 ≥25

24hr urine: <2.8
Renal threshold: 8.9-10.0

24
Q

Describe hyperglycemia as it relates to diabetes

A
  • Impaired fasting gluc
  • Impaired gluc tolerance
  • Diabetes mellitus; Inappropriate hyperglycemia due to defects in insulin secretion/action
25
Q

Describe hypoglycemia

A
  • Plasma gluc is 3.6-3.9
  • Glucagon is released fr. pancreas (inhibit insulin)
  • Epinephrine (acts w/ glucagon)
  • Cortisol and GH to increase gluc production
  • 2.8-3.1 gluc = observable CNS symptoms
26
Q

Symptoms of hypoglycemia

A

Increased hunger, sweating, nausea, vomiting, dizziness, nervousness, tachycardia, shaking, slurred speech, blurred sight, mental confusion

27
Q

Lab findings of hypoglycemia

A

Decreased plasma gluc, extremely high insulin levels in patients w/ insulinoma (small tumor in pancreas that produces excess insulin regardless of blood sugar)

Carbohyrdrates and Microbiology :) (7 decks)

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