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Exam 3 Material Flashcards

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1
Q

Identify three areas of red cell metabolism that are crucial for normal erythrocyte survival and function.

A
  1. RBC membrane
  2. Hemoglobin structure and function
  3. RBC metabolic pathways
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2
Q

Discuss the two major proteins of the red cell membrane, glycophorin and spectrin, according to:

a. Integral versus peripheral protein
b. Major functions for each

A

a. Integral protein: extends through the lipid bilayer and is permanently attached to the cell membrane

Peripheral protein: does not extend though the lipid bilayer, has temporary connections to the cell membrane, forms membrane 
cytoskeleton

b. Glycophorin: accounts for most of the membrane’s sialic acid – giving RBCs its negative charge

Spectrin: strengthens membrane (shape and stability), preserves deformability (pliability)
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3
Q

State the mechanism for producing each of the following types of poikilocytosis that are caused by structural membrane defects:

Acanthocytes

Bite cells

Spherocytes

Target cells:

A

Acanthocytes: an absence of low density lipoproteins (LDLs) leading to malabsorption of fats within the body (i.e. abetalipoproteinemia – acanthocytes)

Bite cells: a decrease in spectrin leading to less deformability – when attempting to pass thorough the spleen, it is very “slow” – the RE may try to phagocyte these cells leaving a portion of the RBC membrane removed

Spherocytes: a decrease in spectrin leading to less deformability – when attempting to pass thorough the spleen, it is very “slow” – the RE may try to phagocyte these cells leaving a reduce surface to volume ratio

Target cells: accumulation of cholesterol in RBC membrane leading to an increased surface area and decreased intracellular hemoglobin

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4
Q

State the protein carrier that delivers iron to the RBC membrane for hemoglobin synthesis.

A

Transferrin

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5
Q

List the two major tissues in the body where heme synthesis occurs.

A
  1. Erythroid marrow
  2. Liver
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6
Q

Diagram the sequence leading to heme synthesis … beginning with succinyl coenzyme A + glycine and ending with heme.

A

Succinyl coenzyme A + glycine to ALA to Porphobilinogen to Uroporphyrinogen to Coproporphyrinogen to Protoporphyrinogen IX to Protoporphyrin IX + Fe = Heme

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7
Q

Describe the chemical structure of heme.

A

Porphyrin is made up of four (4) five-member rings bound by methane bridges – the arrangement of the nitrogen atoms allows it to chelate metal atoms (i.e. iron)

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8
Q

Explain the reason why a patient with lead poisoning presents with “ringed sideroblasts”.

A

Lead damages one or more of the enzymes involved in heme synthesis – it blocks the incorporation of iron into the molecule leading to iron buildup in the mitochondria causing the “ringed sideroblasts”

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9
Q

Explain the reason why a freshly voided urine from a patient with a porphyria may not be red.

A

Porphyrin becomes oxidized from porphyrinogen, which is colorless – it oxidizes with exposure to air or acids – this process can take time

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10
Q

List three hemoglobins that are found exclusively in the embryo.

A
  1. Gower 1: Zeta2 – Epislon2
  2. Gower 2: Alpha2 – Epislon2
  3. Portland: Zeta2 – Gamma2 or Zeta2 - Alpha2
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11
Q

State the globin chain composition and percentages for each of the three normal adult hemoglobins.

A
  1. Hemoglobin A: Alpha2 – Beta2 (>95%)
  2. Hemoglobin A2: Alpha2 – Delta2 (1.5-3.0%)
  3. Hemoglobin F: Alpha2 – Gamma2 (~ 2%)
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12
Q

Characterize the oxygen affinity of the relaxed (R) form and the tense (T) form of the hemoglobin molecule.

A

Relaxed form (R): when hemoglobin has an affinity and readily binds to oxygen via ALL of the iron molecules (oxyhemoglobin – arterial blood)

Tense form (T): when hemoglobin has a lower affinity and readily unloads the oxygen via ALL of the iron molecules – binding of 2,3 DPG occurs (deoxyhemoglobin – venous blood)

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13
Q

Explain the relationship between pO2 of the surrounding medium and the percent of oxygen saturation of hemoglobin as depicted by an oxygen dissociation curve, including the effects of the following:

A

Hemoglobin’s affinity for oxygen based on its location and condition(s) in/of the body

pH: in the tissues – is decreased due to uptake of CO2, etc.
in the lungs – is increased due to expulsion of CO2

2,3 DPG levels: in the tissues – increased (O2 being squeezed out)
in the lungs – decreased (relaxed form of Hgb)

Temperature: in the tissues – increased (i.e. fever)
in the lungs – decreased

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14
Q

Differentiate “shift-to-the right” and “shift-to-the left” in relation to the hemoglobin-oxygen dissociation curve.

A

“Shift-to-the right:” favors the release of oxygen; therefore, lowering the affinity of hemoglobin for oxygen

“Shift-to-the left:” favors the uptake of oxygen; therefore increasing the affinity of hemoglobin for oxygen

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15
Q

List three abnormal hemoglobins that are unable to transport or deliver oxygen.

A
  1. Carboxyhemoglobin
  2. Methemoglobin
  3. Sulhemoglobin
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16
Q

State the main source of ATP production in the mature RBC.

A

Anaerobic breakdown of glucose

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17
Q

Name the metabolic pathway that generates most of the red cell’s ATP.

A

Embden-Meyerhof

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18
Q

State the major function for each of the following red cell metabolic pathways:

Embden-Meyerhof Pathway

Hexose Monophosphate Shunt

Methemoglobin Reductase Pathway

Leubering-Rapaport Shunt

A

Embden-Meyerhof Pathway
90% of the energy needed for the RBC is generated via this pathway – it produces two (2) molecules of ATP, the majority of glucose production and utilization

Hexose Monophosphate Shunt
5-10% glucose utilization (aerobically), protects against hydrogen peroxide which denatures hemoglobin (inherited defect: G-6-PD deficiency)

Methemoglobin Reductase Pathway
Maintains iron in the ferrous (2+) state

Leubering-Rapaport Shunt
Synthesis of 2,3 DPG – profound effect on hemoglobin’s affinity for oxygen, its stores can serve for additional ATP generation

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19
Q

State the changes in the red cell leading to its demise at 120 days.

A

As enzymes decrease, RBCs lose production of energy and deformability and no longer transverse through the microvasculature

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20
Q

Compare and contrast the steps involved in the extravascular versus intravascular breakdown of senescent RBCs.

A

Extravascular:

  1. RES cells phagocyte RBCs
  2. Iron is transported back to BM via transferrin
  3. Globin is return to AA pool
  4. Protophorphyrin ring dissembled – biliverdin converted to bilirubin
  5. Bilrubin is coupled to albumin and transported to liver
  6. Bilirubin converted to urobilinogen and excretedIntravascular:
  7. RBCs break in the lumen of vessel
  8. Haptoglobin picks up the free Hgb
  9. Hapto-Hgb complex goes to the liver for further metabolism – follows the same process as extravascular
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21
Q

State the characteristic level (decreased, normal, or increased) of haptoglobin in the presence of intravascular hemolysis.

A

Decreased – during intravascular hemolysis, destruction of RBCs are occurring within the blood vessel leaving haptoglobin to the vessel to pick-up the free hemoglobin – it would lower the plasma haptoglobin levels that would lead to hemoglobinemia or hemoglobinuria

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22
Q

State the protein carrier for the following:

Bilirubin
Hemoglobin
Iron

A

Bilirubin: albumin
Hemoglobin: haptoglobin
Iron: transferrin

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23
Q

List two general causes for anemia.

A

• Increased loss of RBCs (hemorrhage or hemolysis)
• Decreased production of RBCs (in the BM)

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24
Q

Describe six (general) clinical symptoms of anemia.

A

• Pallor
• Lightheadedness
• Muscle weakness
• Vertigo
• General lethargy
• Dyspnea (shortness of breath)
• Tachycardia (increased heart rate)

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25
Describe the characteristic results you would find in the workup of an anemic patient with regard to the following laboratory tests: Cell profile RBC indices (microcytic-hypochromic anemia) RBC indices (macrocytic anemia) RBC indices (normocytic-normochromic anemia) Reticulocyte count (aplastic anemia) Reticulocyte count (extracorpuscular hemolytic anemia)
Cell profile: decreased RBC count and/or decreased hemoglobin RBC indices (microcytic-hypochromic anemia): MCV< 80 fL, MCHC< 32 g/dL RBC indices (macrocytic anemia): MCV> 100 fL RBC indices (normocytic-normochromic anemia): MCV 80-100 fL, MCHC 32-36 g/dL Reticulocyte count (aplastic anemia): decreased retic count Reticulocyte count (extracorpuscular hemolytic anemia): increased retic count
26
Describe the characteristic RBC morphology you would find with regard to the following diseases/anemias: Extracorpuscular hemolytic anemia Hereditary spherocytosis Liver disease Pernicious anemia Sickle cell anemia Thalassemia Hemoglobinopathy
Extracorpuscular hemolytic anemia: schistocytes and spherocytes Hereditary spherocytosis: spherocytes Liver disease: round macrocytes, targets, stomatocytes, spur cells Pernicious anemia: oval macrocytes and teardrops Sickle cell anemia: sickle cells Thalassemia: M/H w/marked morphology and basophilic stippling Hemoglobinopathy: “targets plus…” – sickle cells, C crystals, SC crystals
27
List the anemias found under the following “morphologic classification of anemias” categories: Microcytic-hypochromic (list four) Macrocytic (list two) Normocytic-normochromic (list three)
Microcytic-hypochromic (list four) • Iron Deficiency Anemia • Anemia of Chronic Inflammation (Disease) • Sideroblastic Anemia • Thalassemias Macrocytic (list two) • Non-megaloblastic Anemia • Megaloblastic Anemia Normocytic-normochromic (list three) • Aplastic Anemia • Hemoglobinpathies • Hemolytic Anemias (other than hemoglobinopathies)
28
State three criteria for accepting a CBC profile.
• H & H in balance • MCHC < 37 • Make sure results make sense!!
29
State the primary function of iron in the body.
Oxygen transport
30
State the six iron compartments of the body (from largest to smallest).
• Hemoglobin • Storage • Myoglobin • Labile Pool • Tissue Iron Department • Transport Compartment
31
List four factors that influence iron absorption.
• Amount and type of iron accessible from food • Functional state of GI mucosa and pancreas • Current iron stores • Erythropoietic needs
32
List three conditions that result in an increased need for iron.
• Growth periods • Blood loss • Diversion of iron to the fetus
33
Name the anatomic site at which iron is absorbed most efficiently.
Duodenum
34
State the function of transferrin.
Iron transport protein
35
Name the organelle that contains iron in the erythrocyte precursors.
Mitochondria
36
Describe what is being measured for each of the following laboratory determinations: Serum iron: TIBC: Serum ferritin: BM macrophage iron: BM sideroblasts: ZPP:
Serum iron: amount of iron (bound to transferrin) in the serum/plasma TIBC: amount of iron that transferrin can bind Serum ferritin: the amount of iron located in the body’s storage BM macrophage iron: iron held by the RE cells in the erythroblastic island that is used to supply the developing RBC precursors in the BM BM sideroblasts: nRBCs in the BM that contain iron ZPP: insufficient iron availability to developing nRBCs – erythrocyte protoporphyrin accumulates in the cell
37
State the relationship between serum ferritin levels and bone marrow iron stores in a healthy individual.
In a healthy person, serum ferritin is equivalent to the body’s storage of iron, in BM
38
Describe the peripheral smear RBC morphology that would prompt the ordering of iron studies.
Hypochromia, Microcytes, Aniso, some poik, variable
39
Discuss, in detail, iron deficiency anemia, including: Causes (infants vs. adults) Clinical signs and symptoms RBC count and/or HGB: PLT count: RBC morphology MCV: MCHC: RDW: Reticulocyte count: Treatment:
Infants: milk anemia – being fed cow’s milk can make it more difficult to absorb iron Adults: poor diet, GI bleeds, malabsorption, mental blood loss, pregnancy Pallor, fatigue, lethargy, SOB – Koilonychia (an abnormal thinness and concavity of the fingernails), heart murmur, peculiar cravings RBC count and/or HGB: decreased PLT count: increased RBC morphology: Hypochromia, Microcytes, Aniso, some poik, variable MCV: decreased MCHC: decreased RDW: increased Reticulocyte count: increased Treatment: treat underlying cause, supplemental iron
40
Discuss the mechanism (pathology) for developing a hypochromic-microcytic anemia for each of the following conditions: Iron deficiency anemia Anemia of chronic inflammation (disease) Sideroblastic anemia
Malabsorption, decreased dietary intake, and increase loss of iron leads to: Decreased iron – decreased Hgb – hypochromia – extra cell divisions – microcytosis BM macrophages fail to give up iron to the RBC precursors; therefore RBCs develop iron deficient An accumulation of iron in the mitochondria of nRBCs that “gets trapped” – porphyria
40
Discuss the mechanism (pathology) for developing a hypochromic-microcytic anemia for each of the following conditions: Iron deficiency anemia Anemia of chronic inflammation (disease) Sideroblastic anemia
Malabsorption, decreased dietary intake, and increase loss of iron leads to: Decreased iron – decreased Hgb – hypochromia – extra cell divisions – microcytosis BM macrophages fail to give up iron to the RBC precursors; therefore RBCs develop iron deficient An accumulation of iron in the mitochondria of nRBCs that “gets trapped” – porphyria
41
Differentiate iron deficiency anemia, anemia of chronic inflammation (disease), and sideroblastic anemia according to the following iron studies: Serum iron Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: increased TIBC Iron deficiency anemia: increased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: decreased Ferritin levels Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): increased Sideroblastic anemia: increased BM macrophage iron Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): increased Sideroblastic anemia: increased BM sideroblasts Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: increased
Serum iron Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: increased TIBC Iron deficiency anemia: increased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: decreased Ferritin levels Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): increased Sideroblastic anemia: increased BM macrophage iron Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): increased Sideroblastic anemia: increased BM sideroblasts Iron deficiency anemia: decreased Anemia of chronic inflammation (disease): decreased Sideroblastic anemia: increased
42
State the reason why long-term iron therapy should not be given to a patient with anemia of chronic inflammation (disease).
The amount of iron isn’t the issue – it’s the release of iron made available to the cells
43
Discuss the reason for the presence of "ringed sideroblasts" upon bone marrow iron exam of a patient with lead poisoning.
Excess iron-laden in the mitochondria form a ring around the nucleus
44
State the characteristic RBC histogram appearance one would expect to see in a patient with sideroblastic anemia, especially a hereditary form.
Two (2) peaks due to the presence of two RBC populations
45
Discuss hereditary hemochromatosis according to complications and treatment.
Iron overload – major concern is location of iron deposits – occurring in certain organs of the body can initiate a fibrotic response
46
State the hemoglobin molecule defect found in a thalassemia.
Defect in the rate of synthesis of one or more of the globin chains
47
Describe the suspected reasoning for the (same) geographic distribution pattern that coincide with the incidence of malaria and the heterozygous state(s) of the thalassemia syndromes.
Being heterozygous is advantageous against malaria – having one altered Hgb gene makes infections with Malaria less likely, but sickle cell and thalassemias can occur within the same individual
48
State the globin chain composition and percentages of the three normal adult hemoglobins.
• Hemoglobin A: Alpha2 – Beta2 (>95%) • Hemoglobin A2: Alpha2 – Delta2 (1.5-3.0%) • Hemoglobin F: Alpha2 – Gamma2 (~ 2%)
49
Describe what is meant by the following nomenclatures as they pertain to the production of globin chains: β0 thalassemia: β+ thalassemia: α0 thalassemia:
β0 thalassemia: beta chains ARE NOT being formed β+ thalassemia: decreased production of beta chains α0 thalassemia: alpha chains ARE NOT being formed
50
List the four genetic possibilities that may occur with an alpha thalassemia.
• No alpha chain production • One alpha chain functioning – 3 deleted • Two alpha chain functioning – 2 deleted • Three alpha chain functioning – 1 deleted
51
Discuss, in detail, Beta Thalassemia Major, including: Pathology Ethnic distribution Clinical features and course of disease CBC results RBC morphology Retic count BM exam Hemoglobin electrophoretic pattern Treatment
Pathology Reduced and/or absent beta chain production – alpha chain synthesis occurs at a normal rate creating an imbalance and leading to precipitation of excess alpha chains resulting in Heinz bodies Ethnic distribution Mediterranean area and SE Asia Clinical features and course of disease • Onset in early childhood • Severe hemolytic anemia • “too many RBCs for Hgb” • Shorten life span CBC results “Too many RBCs for the Hgb” RBC morphology Mk’d aniso, poly, hypo, and micro Mk’d poik w/ targets, schistos, spheres, tears Inclusions nRBCs Retic count Increased BM exam Marked erythroid hyperplasia (a lot of immature RBCs) Increase in iron stores Hemoglobin electrophoretic pattern 40-60% F Increased A2 Decreased A (or absent) F > A2 – has an greater affinity for oxygen so we observe an increase F before A2 A2/C, S, F, A (shortest to longest distance) Treatment Regular transfusions Iron chelation therapy Splenectomy Diet restrictions Vitamin B & Folate supplementation
52
Discuss the two mechanisms responsible for the early RBC destruction (hemolysis) as seen in Beta Thalassemia Major.
• Cells in the BM w/ Heinz bodies leads to ineffective erythropoiesis • Cells in the circulation w/ Heinz bodies leads to intravascular hemolysis
53
Discuss the reason(s) why patients with Beta Thalassemia Major have the following findings: "hair-on-end" appearance on skull x-rays and Mongoloid appearance to face
Due to an increase in hematopoiesis that has caused an expansion of the BM
54
State the results of the following chemistry tests as expected during any hemolytic process... including Beta Thalassemia Major:
Plasma haptoglobin: decreased Serum bilirubin: increased Serum ferritin: increased Serum iron: increased
55
Discuss, in detail, Beta Thalassemia Minor, including: Pathology Ethnic origin: Clinical features and course of disease: CBC results: RBC morphology: Retic count: BM exam: Hemoglobin electrophoretic pattern Treatment:
Pathology: reduced rate of beta chain production Ethnic origin: Mediterranean area, SE Asia, Black population of North America and West Africa Clinical features and course of disease: mild, asymptomatic hemolytic anemia, slight splenomegaly, normal life span CBC results: “Too many RBCs for the Hgb” RBC morphology: Slt.-Mod for all morphology relative to Major (aniso, poly, hypo, and micro -- poik w/ targets, schistos, spheres, tears – inclusions and nRBCs Retic count: slightly increased BM exam: Mild – mod. erythroid hyperplasia (a lot of immature RBCs) Increase in iron stores Hemoglobin electrophoretic pattern Hgb A predominates – increase in A2 (greater than %5) – increase in F (1-5%) Treatment: Not usually required
56
Compare and contrast Beta Thalassemia Minor with Iron Deficiency Anemia according to the following parameters: RBC count: Beta Thalassemia Minor: Iron Deficiency Anemia: Hemoglobin value Beta Thalassemia Minor: Iron Deficiency Anemia: Hgb A2 level Beta Thalassemia Minor Iron Deficiency Anemia ZPP Beta Thalassemia Minor: Iron Deficiency Anemia:
RBC count: Beta Thalassemia Minor: increased Iron Deficiency Anemia: decreased Hemoglobin value Beta Thalassemia Minor: >10 g/dL Iron Deficiency Anemia: <10 g/dL Hgb A2 level Beta Thalassemia Minor: >5% Iron Deficiency Anemia: normal ZPP Beta Thalassemia Minor: normal Iron Deficiency Anemia: increased
57
Discuss Hydrops Fetalis Syndrome according to: Pathology of the hemoglobin molecule: Globin chain makeup: Ethnic distribution: Compatibility with life:
Pathology of the hemoglobin molecule: no alpha chain production Globin chain makeup: Bart’s = gamma4 Ethnic distribution: SE Asia & Filipino population Compatibility with life: Death in utero/shortly after delivery
58
Discuss Hemoglobin H disease according to: Pathology of the hemoglobin molecule Globin chain makeup: Unusual characteristic of Heinz bodies:
Pathology of the hemoglobin molecule: one functioning alpha chain Globin chain makeup: Hgb H = beta4 Unusual characteristic of Heinz bodies: RBCs so full of Heinz bodies – “raspberry” appearance
59
Discuss Hemoglobin Lepore according to: Pathology of the hemoglobin molecule: Hemoglobins being produced in homozygous state:
Pathology of the hemoglobin molecule: fused delta and beta chain Hemoglobins being produced in homozygous state: produces ~80% Hgb F and make a Lepore with the fused delta and beta chains ~20%
60
Describe the condition known as Hereditary Persistence of Hemoglobin F (HPFH).
Persistence of fetal hemoglobin in adult life Homozygous state (rare) -- 100% Hemoglobin F Heterozygous – A > Hgb F (15-30%)
61
Discuss the Kleihauer-Betke stain according to: Principle: Normal values: Staining pattern with HPFH: Staining pattern with hemoglobinopathies (other than HPFH): Appearance of hemoglobin A (adult) cells on smear: Appearance of hemoglobin F (fetal) cells on smear:
Principle: assess the distribution of Hgb F in the RBC Normal values: adults < 0.01%, Staining pattern with HPFH: consistently dark pink Staining pattern with hemoglobinopathies (other than HPFH): “speckled” Appearance of hemoglobin A (adult) cells on smear: “Ghost cells” Appearance of hemoglobin F (fetal) cells on smear: Dark pink
62
Describe Heinz bodies with regard to: Three supravital stain used to detect them: Appearance on Wright stain: Composition in: homozygous beta thalassemia: homozygous alpha0 thalassemia: hemoglobin H disease:
Three supravital stain used to detect them: crystal violet, new methylene blue, brilliant cresyl blue Appearance on Wright stain: CAN NOT SEE Composition in: homozygous beta thalassemia: precipitated Hgb – all alpha globins homozygous alpha0 thalassemia: precipitated Hgb – all gamma globins hemoglobin H disease: precipitated Hgb – all beta globins

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