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CPR > Erythrocyte Biochemistry > Flashcards

Erythrocyte Biochemistry Flashcards

1
Q

Hemoglobin is made via ____ before extrusion of their nucleus

A

Normablast

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2
Q

List the events of O2 Binding to Heme

A

1) Fe2+ = out of plane 2) O2 Binds and brings Fe2+ into plane 3) Proximal F8 Histidine pulled down 4) Distal Histidine Stabilizes and Provides hydrogen bonds

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3
Q

Myoglobin has a ___ curve

A

Hyperbolic

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4
Q

Hemoglobin has a __ curve

A

Sigmoidal

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5
Q

Describe Positive Cooperativity

A

1) O2 binds to heme and facilitates more binding

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6
Q

How does exercise influence O2 delivery

A

1) Decreases PO2 in tissues –> more efficient delivery ** Remember O2 wants to go from high to low

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7
Q

What is 2,3 BPG made by? How does it have an effect on oxygen delivery?

A

Metabolizing Tissues Promotes delivery of O2 to Tissues

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8
Q

What is the Bohr Effect?

A

Lower pH –> better oxygen delivery

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9
Q

Discuss how 2,3 BPG has an effect on HbF and HbA

A

2,3 BPG effects HbA but not HbF –> HbF increased affinity for O2 vs mother

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10
Q

Describe the Sickle Cell Anemia Mutation

A

1) Position 6
2) Glutamic Acid (-) to Valine (hydrophobic)

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11
Q

What are the two storage forms of Iron?

A

1) Ferritin
2) Hemosiderin

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12
Q

What is hemosiderin

A

Iron Storage Complex that is composed of partially digested ferritin and lysosome

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13
Q

How does Fe2+ get into cell

A

Diffusion through membrane

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14
Q

How does Fe3+ get into cell?

A

1) Converted to Fe2+ via Duodenal Cytochrome B (Ferric Reductase) with aid of Vit. C
2) Fe 2+ enters via DMT1
3) To fates
- Storage: Converted to Fe3+ via Ferroxidase (cerruloplasmin) –> Ferritin
- Transported to blood via Ferroportin

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15
Q

What transports iron to the target tissues?

A

Transferrin

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16
Q

Starting with Fe2+ entering blood via Ferroportin, describe how iron gets to target tissues.

A

1) Fe2+ converted to Fe3+ via Ferroxidase
2) Fe3+ binds Transferrin
3) Transferrin binds TfR
4) Complex is internalized via clathrin mediated endocytosis
5) Complex is in Endosome –> decrease pH
6) Releases Transferrin from TfR
7) Endosome docks mitochondria and transfers iron to mito via DMT1

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17
Q

How does iron get into the mitochondria? (Channel)

A

DMT1

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18
Q

Ferroportin requires ___

A

Hephaestin

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19
Q

What negatively regulates Ferroportin?

A

Hepcidin

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20
Q

Nonheme iron is converted to Fe2+ via ___. What does this enzyme require?

A

1) Duodenal Cytochrome B (Ferric Reductase)
2) Vitamin C

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21
Q

When Hepcidin binds ferroportin what occurs?

A

Internalization and degradation via Lysosomes

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22
Q

What regulates Hepcidin (3x)

A

Transferrin

Hepcidin Receptor

HFE (Human Homeostatic Iron Regulatior Protien)

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23
Q

What is Hypochromic Microcytic Anemia caused by?

A

Iron Def.

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24
Q

How would you teat Hypochromic Microcytic Anemia ?

A

Dietary Supplement

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25
Q

Characterize Hypochromic Microcytic Anemia

A

Small Pale RBC w/ decreased hemoglobin

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26
Q

What is Hereditary Hemochromotosis or HH)

A

Iron Overload

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27
Q

What Mutation occurs in Hereditary Hemochromatosis?

A

HFE (Hereditary hemochromatosis gene)

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28
Q

Where is iron accumlated in HH?

A

1) Heart –> Heart Failure
2) Liver –> Cirrhosis and Hepatocellular Carcinoma
3) Pancreas –> Diabetes

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29
Q

What is the active form of folate?

A

THF

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30
Q

Folate is reduced to DHF via what? (This is also the same enzyme that is reduces DHF to THF)

A

Dihydrofolate Reductase

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31
Q

Function of Folate

A

DNA synthesis (Purines and Pyrimidine Thymine)

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32
Q

Def. Folate causes ….

A

Decreased DNA synthesis –> Megaloblastic Macrocytic Anemia

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33
Q

Where is Folate Absorbed

A

SI

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34
Q

Where is Folate stored?

A

Liver

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35
Q

Folic acid is converted to ___ when absorbed which is the primary circulating form.

A

N5-methyl-THF

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36
Q

How does N5-methyl-THF convert to THF?

A

Vit. B12

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37
Q

What is the job of Vit B12 in converting N5-methyl-THF?

A

Transfers Methyl Group

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38
Q

What is the dietary form of folate?

A

DHF

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39
Q

Function of Methotrexate

A

Antineoplastic agent and inhibitor of DNA Synthesis

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40
Q

What enzyme does Methotrexate inhibit

A

Dihydrofolate Reductase

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41
Q

Another name for Vit B12

A

Cobalamine

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42
Q

How do humans get Vit. B12

A

Animal products

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43
Q

Where is Vit. B12 absorbed?

A

Ileum via Intrinsic Factor

44
Q

How is the Intrinsic Factor - Vit. B12 complex carried through the blood?

A

Transcobalamin II

45
Q

How is Intrinsic Factor - B12 complex taken up by cells

A

Receptor Mediated Endocytosis

46
Q

Pernicious anemia is caused by

A

Def. B12

47
Q

Pernicious Anemia is normally caused by ___

A

Destruction of Gastric Mucosa

48
Q

Total Serum Folate and Serum B12 in Pernicious Anemia

A

1) Folate: <3ng/mL
2) < 350pg/mL

49
Q

Schilling Test importance

A

Determining cause of PErnicious Anemia

50
Q

How is Schilling Test Formed

A

Radioactive B12 ingested

51
Q

if Radioactive B12 present in urine what does that mean

A

Normal Absoprtion and Pernicious Anemia due to B12 Deficient Diet

52
Q

Location of Biosynthesis opf Heme

A

Liver and Erythroid cells of bone marrow

53
Q

Where does Heme Production occur with in the cell?

A

Mitochondria and Cytosol

54
Q

How many Phases are in Heme Biosynthesis? List their Location as well with in cell.

A

1) Phase I: Mitochondria
2) Phase 2: Cytosol
3) Phase 3) Mitochondria

55
Q

Describe the Rxn in Phase I in Heme biosynthesis.

A

Rxn: Glycine + Succinyl CoA –> d-aminolevulinic acid (ALA)

Enzyme: ALA Synthase (Vit B6)

56
Q

What is the end product of Phase I

A

ALA

57
Q

What is the goal of Phase II of heme biosynthesis

A

Coproporphyrinogen III Generation

58
Q

List the rxns of Phase 2 without the enzymes added

A

RXN: 1) 2x ALA –> Phorphobilinogen (PBG)

2) Porphobilinogen –> Hydroxymethylbilane
3) Hydroxymethlybilane –> Uroporphyrinogen
4) Coproporphyrinogen Generation

59
Q

Function of ALA Synthase, ALA Dehydratase, and Porphobilinogen Deaminase

A

1) ALA Synthase: Glycine + Succinyl CoA –> ALA
2) ALA Dehydratase: 2x ALA –> Porphobilinogen (PBG)
3) Porphobilinogen Deaminase: Porphobilinogen –> Hydroxymethylbilane

60
Q

What is the Goal of Phase III?

A

Generation of Protoporphyrin and introduction of iron to form heme

61
Q

How does Protoporphyrin IX get converted into heme in Phase II of heme biosynthesis

A

Ferrochelatase

62
Q

What does ALA synthase require

A

Vit B6 (Pyridoxial Phosphate)

63
Q

What occure with Vit B6 def. (3x)

A

Heme Syntesis is deminished

RBCs are pale

Ironstore increase

64
Q

What are the two Isoforms of ALA Synthase

A

ALAS I (Ubiquitous)

ALAS II (Erythroid Cells)

65
Q

ALAS I and ALAS II are inhibited by… (2x)

A

1) Heme
2) Hemin

66
Q

ALAS II increases its transcription and translation in the presence of ___

A

Iron

67
Q

Lead Poisoning: Lead inhibits what two enzymes?

A

1) ALA Dehydratase (contains Zn) and Ferrochelatase (Contains Fe)

68
Q

Lead Poisoning: If ALA Dehydratase is inhibited then what would you expect to see in the patient?

A

1) Increased ALA
2) Neurotoxicity and Neurological Symptoms due to ALA being a Neurotoxin

69
Q

Lead Poisoning Effects: 4x

A

1) Neurological Symptoms
2) Decreased Heme Production
3) Prescence of Hypochromic Microcytic anemia
4) impacted ATP and Energy Metabolism

70
Q

What are Porphyrins?

A

Inherrited Metabolic Disorders with defects in heme synthesis

71
Q

What are the two categories of Porphyrins. Describe symptoms.

A

1) Actue Hepatic: Neurological
2) Erythropoietic: Skin and Photosensirivity

72
Q

Congenital Erythropoietic Porphyrin Cause

A

Defective Uroporphrinogen III Synthase (Erythrocytes)

73
Q

Symptoms of Congenital Erythropoietic Porphyrin

A

1) Photosensitivity
2) Red Color Urine and teeth
3) Hemolytic Anemia

74
Q

Results of Congenital Erythropoietic Porphyrin

A

1) Increased Uroprophyrinogen I and its red color
- Air oxidation production of urporphyrin I

75
Q

Cause of Celebrity Porphyrias (Varigate Porphyrin)

A

Protoporphyrinogen IX oxidase Def.

76
Q

Symptoms of Celebrity Porphyrias (Varigate Porphyrin)

A

1) Photosensitivity
2) Neurological Symptoms
3) Developmental Delay in Children
4) Hallucinations, Delulsions, Convulsions

77
Q

What system is heme degraded by?

A

Reticulo-endothelial system

78
Q

Describe Heme Degradation RXN and Enzymes

A

RXN: Heme (Porphyrin Ring) –> Biliverdin –> Bilirubin (Tetrapyrrole Ring)

Enzymes:

—–Heme Oxygenase + O2–> Biliverdin + CO

—–Biliverdin Reductase + NADPH

79
Q

Heme Oxygenase reduces Ferrous iron to ____

A

Ferric

80
Q

What is the rate limiting step in Conjugation of Bilirubin

A

UDP Glucuronyl Transferase

81
Q

How is Bilirubin and Albumin Complex removed from blood

A

Liver Uptake

82
Q

Mechanism of BR Conjugation

A

1) UDP-Glucose Dehydrogenase: UDP Glucose –> UDP-Glucuronate
2) Bilirubin EDP Glucuronyltransferase: 2UDP-glucuronate + Bilituin IXa –> Bilirubin Diglucuronide

83
Q

Why is Bilirubin Congugated?

A

B/C its insouble and needs to be converted to be safely excreted

84
Q

List the steps in heme degradation

A

1) Heme oxygenase: Coverts Heme to Biliverdin (green pigment)
2) Biliverdin Reductase: Biliverdin –> Bilirubin
3) Bilirubin complexed w/ albumin released to blood
4) Congugation occurs in liver and released into gall bladder
5) SI microbes reduce Bilirubin to urobilinogen
6) Two Fates of Urobilinogen
- Resorbed and converted to Urobilin via kidneys
- Further Microbe reduction to Stercobilin (found in feces)

85
Q

Jaundice is cause by ___

A

Hyperbilrubinemia

86
Q

3 Types of Jaundice

A

1) Pre Hepatic
2) Intra Hepatic
3) Post Hepatic

87
Q

What type of BR is increased in Pre Hepatic Jaundice

A

Unconjugated

88
Q

Cause of Pre Hepatic Jaundice (2x)

A

Excess Hemolysis due to hemolytic Diseases

Internal Hemmorage

89
Q

Glucose 6-P dehydrogenase Def. causes __ Jaundice

A

Pre Hepatic

90
Q

Intrahepatic Jaundice is due to

A

Impaired hepatic uptake, conjugation, or secretion of conjugated BR

91
Q

Disease Examples associated with Intra Hepatic jaundice

A

1) Criggler - Najjar Syndrome
2) Gilberts Syndrome

92
Q

Post Hepatic Jaudice is caused by (3x)

A

1) Obstruction to biliary tree
2) Cholangiocarcinoma
3) Gall Stones

93
Q

What type of BR is increased in Post Hepatic Jaundice

A

Conjugated

94
Q

Relative lab values and symptoms of Post Hepatic Jaundice

A

1) Increased blood conjugated BR
2) Dark Urine
3) Pale Stool (No Sterobilin)
4) Increased Alkaline Phosphate (ALP)

95
Q

UDP- GT- Related Disorders:

A

1) Type I Criggler - Najjar Syndrome
2) Type II Criggler - Najjar Syndrome
3) Gilberts

96
Q

Cause for Type I Criggler

A

Complete Absence of UDP-GT gene

97
Q

Results of Type I Criggler

A

1) Severe Hyperbilirubinemia
- Accumulates in brains of babies –> encephelopathy (Kernicturus)

98
Q

Type II Criggler cause

A

Mutant UDP GT gene (enzyme has 10% activity)

99
Q

Cause of gilberts Syndrome

A

Reduced activity of UDP-GT (25% activity)

100
Q

What is Hepatitis

A

Inflammation of liver leading to liver dysfunction

101
Q

What type of BR is elevated in hepatitis?

A

Unconjugated and Conjugated

102
Q

Causes of hepatitis (3x)

A

1) Viral Infections
2) Alcoholic Cirrhosis
3) Liver Cancer

103
Q

Symptoms of Hepatitis due to BR accumulation

A

1) Yellow Discoloration of skin and sclera
2) Dark, Tea colored Urin

104
Q

List the Colors of Bruises and their culprit

A

1) Red - Heme
2) Green - Biliverdin
3) Orange - Bilirubin
4) Reddish Brown - Hemosiderin

105
Q

Cause of Neonatal (Physiologic) Jaundice

A

Unable to conjugate and excrete bilirubin due to UDP-GT def.

106
Q

Treatment of Neonatal Jaundice (2X)

A

Phototherapy

Inhibition of Heme Oxygenase

107
Q
A

CPR (18 decks)

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