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Y1S2Pathology > RBC's Disorders > Flashcards

RBC's Disorders Flashcards

1
Q

What are the different organs that make RBCs throughout our lives?

A

1) Blood islands in the yolk sac

2) Spleen

3) Liver

4) Lymph nodes

After birth:

5) Bone marrow (first in the distal long bones then in the axial skeleton in adults)

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2
Q

Describe the normal composition of the bone marrow

A
  • Normally it is made of 50% fat and 50% bone marrow
  • Bone marrow abnormalities could be hypercellular or hypocellular (increased fat and decreased hematopoietic cells, which could be due to medication or hereditary)
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3
Q

What is anemia?

A

It is an abnormality of the RBCs where there is decreased RBC PCV, and hemoglobin concentration measured by the hematocrit (Ht, HCT) affecting tissue oxygenation, where the patients will suffer from fatigue, shortness of breath, and palpitations

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4
Q

What are the different classifications of anemia?

A

1) Blood loss:
- Acute (trauma)
- Chronic (menstruation, GIT bleeding, etc)

2) Increased rate of destruction (hemolytic anemia):
- Heredity (disorders with the cytoskeleton of the RBCs), Favism (G6PD deficiency, which protects the RBCs from oxidative stress, and could occur when individuals consume fava beans)

  • Acquired: in cases of incompatible blood transfusion

3) Failure of RBC production:
- Aplastic anemia
- Defective DNA synthesis (deficiency of vitamin B12 and folic acid)
- Deficient heme synthesis (iron deficiency)
- Deficient globin synthesis (thalassemia)

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5
Q

What are the different ways to measure hemoglobin levels?

A

1) Hematocrit

2) Packed cell volume

3) Erythrocyte volume fraction (EVF)

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6
Q

What are the different terminologies when it comes to anemia?

A

1) Mean cell volume (MCV): the average volume of RBC (helps in identifying the type of anemia normal is 82-96, <80= microcytic anemia, >100 = macrocytic anemia)

2) Mean cell hemoglobin (MCH): the average mass of Hb per RBC

3) Mean cell hemoglobin concentration (MCHC): The average conc of Hb in a given volume of RBC

4) Red cell distribution (RCD): the coefficient of variation of red cell volume

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7
Q

How to diagnose different types of anemias?

A

1) Measure the amount of Hb if it is abnormal then

2) Measure the MCV:

  • if it is low, then you measure the ferritin levels if it is low then it is an iron deficiency anemia, on the other hand, if the ferritin levels are high then it is probably an anemia of chronic disease/(congenital Hb disease)
  • If MCV levels are high then you measure the vitamin B12 and folate levels if they where low then it is megaloblastic anemia
  • If MCV levels were normal then you measure the number of reticulocytes, if they were high then it is hemolytic anemia or blood loss anemia, if it was low then it is an anemia of chronic disease, renal failure, or marrow failure
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8
Q

Describe the anemia of blood loss

A

1) Acute blood loss:
- Depends on the rate of blood loss and whether internal or external, and the loss of intravascular volume can lead to CV collapse, shock, and death, after several days the reticulocyte count increases by 10 to 15% as the marrow tries to compensate for it

2) Chronic blood loss:
- Chronic blood loss induces anemia only when the rate of loss exceeds the regenerative capacity or when iron reserves are depleted

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9
Q

Describe iron deficiency anemia

A
  • Most common nutritional disorder
  • The iron balance is maintained largely by regulating the absorption of dietary iron
  • Total iron in the body of a woman is 2 gm, and 6 gm
  • Our normal diet is usually sufficient with IRON as 20% of heme iron is absorbable
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10
Q

What are the different storage sites of iron in the body/

A

1) Functional storage 80% (found in hemoglobin and myoglobin)

2) Storage form (ferritin and hemosiderin) 15-20%

  • Iron balance is easily tipped into a diffeciency as in excessive loss associated with menstruation and increased demand in pregnancy
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11
Q

What are the causes of iron deficiency anemia?

A

1) Insufficient iron intake (especially in vegetarians)

2) Impaired iron absorption

3) Increased requirement

4) Chronic blood loss (peptic ulcers, internal-hemorrhage, etc)

5) Sudden blood loss due to injury

6) High intake of polyphenols

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12
Q

What are the clinical features found in iron deficiency anemia?

A

1) Koilonychia

2) Alopecia

3) Atrophic changes in the tongue (angular glossitis) and gastric mucosa

4) Intestinal malabsorption

5) Angular cheilosis (beside the lips)

  • These inflammatory reactions occur as iron is an important cofactor of a lot of enzymes
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13
Q

How to diagnose iron deficiency anemia?

A

1) Low Hb count

2) MCV <80

3) Ferritin in the body is low

4) Total iron binding capacity is high (due to it being rare)

Microscopic Photo:
- Smaller than normal RBCs (microcytic anemia)

  • Increased zone of central pallor (hypochromic RBC)
  • Increased anisocytosis (variation in size) and poikilocytosis (variation in shape)
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14
Q

What is a megaloblastic anemia?

A
  • Vitamin b12 /folate deficiency anemia
  • Vitamin B12 and folate are coenzymes that are required for the synthesis of thymidine a base found in the DNA, this will result in a defective nuclear maturation delaying cell division
  • It is the second most common type of anemia
  • This type of anemia is characterized by macrocytic RBC and pancytopenia (all hematopoietic cells will be reduced)
  • Pernicious anemia is one of its causes, an autoimmune disease, that causes gastric atrophy and vitamin B12 absorption insufficiency
  • Folic acid is very important in a pregnant woman to avoid NTD (neural tube defects)
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15
Q

What is the etiology of pernicious anemia?

A

1) Malnutrition

2) Antibodies against intrinsic factors (pernicious anemia)

3) Gastrectomy (ileal resection)

4) Inflammatory bowel disease

5) Malabsorption syndrome

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16
Q

Describe the pathogenesis of megaloblastic anemia

A

1) Decrease in vitamin B12 or folate

2) Decreased DNA synthesis

3) Failure of RBC synthesis, maturation, and division

4) Megaloblastic cells

5) Decrease in RBC count

6) Decreased WBC count (pancytopenia)

16
Q

How to diagnose megaloblastic anemia?

A

1) Decreased b count

2) Increased MCV (>100)

3) Low levels of vitamin b12and folate

Microscopic Photo:

1) Macrocytes & macrovalocytes (oval instead of rounded)
2) Hypersegmeted neutrophil (8 lobes instead of the usual 3-5 “due to defect in the maturation)
3) Normochromic (normal polarity of RBC)
4) Different sizes of RBCs (anisocytosis)
5) Different shapes of RBCs (poikilocytosis)
6) Basophilic stippling (bluish area inside of RBC due to problems in the maturation of RBC where the ribosome will be collected, and sometimes we will see DNA

17
Q

What are the different hereditary RBC disorders?

A

1) Membrane disorders
- Spherocytosis, Elliptocytosis
(common in our area due to consaguinity)

2) Hemoglobin disorders
- Hemoglobinopathies, Sickle cell, HbC, etc
- Thalassemia syndromes, a & b

3) Enzyme disorders
- G6DP, PK Deficiencies

18
Q

Describe heredity spherocytosis

A
  • It is an Autosomal dominant inherited defect in the red cell membrane skeleton (proteins that stabilize the RBC lipid bilayer “they lack spectrin”), which leads to the formation of spherocytes (non-deformable cells that are highly vulnerable)
  • The biconcave shape of RBC is not preserved
19
Q

What are the characteristics of hereditary spherocytosis?

A

1) Jaundice

2) Hemolysis of RBC

3) High MCHC (due to the structural changes of the RBC)

4) Gallstones, as they can accumulate in the body

5) Splenomegaly, as some of the accumulated RBC pools down

20
Q

How to diagnose hereditary spherocytosis?

A

1) Osmotic fragility test (OFT):
- It measures the ability of cells to take up fluid without lysing

  • RBC is suspended in a series of tubes containing hypotonic solution of varying 0-0.9 NaCl conc, in hereditary spherocytosis RBC will lyse easily

2)Microscopic photo:

1) Small RBC
2) Lacks central zone of pallor
3) Sphered RBC

21
Q

What is meant by hemoglobinopathies?

A
  • A group of hereditary disorders caused by inherited mutations that lead to structural abnormalities in hemoglobin
  • They can be qualitative or quantitative
  • Qualitative involves the production of globin protein chains, in an amino acid deletion or substitution causing a structural variation of the globin chains (Hb-S, Hb-C, Hb-M, etc)
  • Quantitative involves a genetic defect that reduces the synthesis of globin chains but they are structurally normal (thalassemia)
22
Q

Describe the normal hemoglobin constituents

A

Normal Hb is a tetramer composed of two pairs of similar chains on average:

  • Hb-A (a2,b2) 96%
  • Hb-A2 (a2,d2) 3%
    -Hb-F (a2, y2) 1%
23
Q

What is sickle cell anemia?

A
  • It is a type of hereditary hemoglobinopathy characterized by the production of defective hemoglobin
  • It is caused by a point mutation at position 6 of the b-globin chains by substituting the glutamic acid residue with valine
  • When the body undergoes a hypoxic state, the sickled hemoglobin molecules will assemble into long needle-like fibers with red cells producing a distorted sickled shape cell which could obstruct a BV, cause pain or ischemia
24
Q

What are the clinical manifestations of sickle cell anemia?

A

Due to hemolysis of RBC:
1) Anemia

2) Jaundice

3) Gall stones

Due to microvascular occlusion:
4) Leg ulcers

5) Auto-splenectomy

6) Crisis

7) Stroke (if the block happens in the brain)

8) Pain

9) Acute chest syndrome (if it blocks BV in the lungs)

25
Q

How to diagnose sickle cell anemia?

A

Microscopic photo:

1) Sickeled cells

2) Different RBC sizes and shapes (anisocytosis and poikilocytosis)

26
Q

What is thalassemia?

A
  • Inherited disorders that decrease the synthesis of a-/b-globin chains due to mutations
  • This will result in a deficiency in hemoglobin and structural changes to the RBC due to the relative excess of the unaffected globin chains
  • Along with HbS it is hypothesized that thalassemia is protective against falciparum malaria
27
Q

What are the different types of thalassemia?

A

1) a-thalassemia

2) B-thalassemia

28
Q

What is meant by b-thalassemia

A

There are two mutations that can cause B-thalassemia

1) b0, where there is no b-globin chains produced

2) b+, where they’re is reduced b-globin chain synthesis

29
Q

What are the clinical presentation of b-thalassemia major?

A
  • The problem with these patients is that they require a lot of blood transfusions

1) General features:
- Pallor
- Fatigue
- Dyspnea on exertion
- Poor appetite
- Palpitations
- Poor growth

2) Features of hemolysis:
- Jaundice
- Hyperuricemia (gout)
- Gallstones

3) Excessive erythropoiesis:
- Maxillary overgrowth (chipmunk)
- Increased spaces of teeth
- Frontal bossing
- Chronic sinusitis
- Impaired hearing

30
Q

What are the different types of B-thalassemia?

A

1) b-thalassemia minor, when a person inherits one abnormal allele. it is mildly symptomatic (b+,b or b0,b)

2) b-thalassemia intermedia, when a person inherits two alleles of b+ (b+,b+ or b+,b0)

3) b-thalassemia major, when a person inherits two alleles of b0 (b0,b0)

31
Q

Describe the microscopic photo of b-thalassemia major

A

1) Mexican hat/polychromasia “different color of the RBC” (RBC will have a pink color then palor then pink color again)

2) Nucleated RBC (as RBCs are hemolyzed, some RBCs will be released immature)

31
Q

What is a-thalassemia?

A
  • They are deletions that involve one or more a-globin genes
  • The severity of the disease depends on the number of a-globin genes that are missing
32
Q

What are the types of a-thalassemia?

A

1) Loss of 1 a-globin gene (silent carrier)

2) Loss of two a-globin genes is asymptomatic also

3) Loss of 3 a-globin genes, leads to excess production of b-globin (HbH) or the production of Y-globins (Hb-Bart) both of these Hb have a high affinity for O2 which makes them ineffective at oxygen delivery

4) Loss of four a-globin genes is lethal and incompatible with life

33
Q

What is the treatment of thalassemia

A

Stem cell transplantation

34
Q

What is G6PD Deficiency?

A
  • Glucose-6-phosphate dehydrogenase deficiency
  • Nonimmune hemolytic anemia
  • An x-linked disease that will lead to hemolytic anemia due to the increased oxidative stress which will result in the RBC being composed of denatured hemoglobin, and then the macrophages will remove this hemoglobin resulting in a Heinz bodies RBC in the smear

Y1S2Pathology (8 decks)

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