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3rd Year - Haematology > 3.1. Red Cells - Physiology and Congenital Anaemias > Flashcards

3.1. Red Cells - Physiology and Congenital Anaemias Flashcards

1
Q

What is Anaemia?

A

Reduction in Red Cells or their Haemoglobin Content due to:

  1. Blood Loss
  2. Increased Destruction
  3. Lack of Production
  4. Defective Production
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2
Q

What is the Red Cell Production Pathway in Marrow?

A
  1. Stem Cell - Haemocytoblast
  2. Committed Cell - Proerythroblast
    Development Pathway:
  3. Early Erythroblast - Ribosome Synthesis (Phase 1)
  4. Late Erythroblast - Haemoglobin Accumulation (Phase 2)
  5. Normoblast - Ejection of Nucleus (Phase 3)
  6. Reticulocyte - These can also appear in the Blood
  7. Erythrocyte
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3
Q

What Substances are Required for Red Cell Production?

A
  1. Metals - Iron / Copper / Cobalt / Manganese
  2. Vitamins - B12 / Folic Acid / Thiamine / B6 / C / E
  3. Amino-Acids
  4. Hormones - Erythropoietin / GM-CSF / Androgens / Thyroxine / SCF
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4
Q

In what System does Red Cell Breakdown occur?

A

The Reticuloendothelial System

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5
Q

What happens to the:

  1. Globin, in the Reticuloendothelial System?
  2. Haem, in the Reticuloendothelial System?
A
  1. Amino-Acids are Reutilised
  2. a) Iron - Reutilised, forming Bilirubin
  3. b) (Unconjugated) Bilirubin is Bound to Albumin and transported to the Liver in the Blood
  4. c) Bilirubin is Conjugated in the Liver to form Urobilinogen which is Excreted
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6
Q

What are the 3 areas which Erythrocyte Genetic Defects occur in?

A
  1. Cell Membrane - Skeletal Proteins
  2. Cell Enzymes (Metabolic Pathways)
  3. Haemoglobin
    Note - These result in Reduced Erythrocyte Survival
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7
Q

What is the most common Cell Membrane Erythrocyte Genetic Defect?

A

Hereditary Spherocytosis (Red Cells are Spherical) - Defect in:

  1. Ankyrin
  2. Alpha Spectrin
  3. Beta Spectrin
  4. Band 3
  5. Protein 4.2
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8
Q

What is the Clinical Presentation of Hereditary Spherocytosis?

A
  1. Anaemia
  2. Jaundice (Neonatal)
  3. Splenomegaly
  4. Pigment Gallstones
    Note - Due to these Cells being Abnormal, they are removed quicker from Circulation by the Spleen
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9
Q

What is the Treatment of Hereditary Spherocytosis?

A
  1. Folic Acid (Increased Requirements)
  2. Transfusion
  3. Splenectomy - Remove the Site of Destruction
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10
Q

What are Rare Cell Membrane Erythrocyte Genetic Defects?

A
  1. Hereditary Elliptocytosis
  2. Hereditary Pyropoikilocytosis
  3. South-East Asian Ovalocytosis
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11
Q

What is the Most Common Cell Enzyme (Metabolic Pathway) Erythrocyte Genetic Defect?

A

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency
Note - There are Many Genetic Variants
Note - This is X Linked (Affects Males, Female Carriers)

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12
Q

What is the Function of Glucose-6-Phosphate Dehydrogenase (G6PD) in the Normal Erythrocyte?

A

It is involved in Producing NADPH which protects against Oxidative Damage

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13
Q

What is the Clinical Presentation of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency?

A
  1. Neonatal Jaundice
  2. Drug / Broad Bean / Infection Precipitated Jaundice and Anaemia - Intravascular Haemolysis / Haemoglobinuria
  3. Splenomegaly
  4. Pigment Gallstones
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14
Q

In Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency, what are the Triggers of Haemolysis?

A
  1. Infection
  2. Acute Illness - DKA
  3. Drugs:
  4. a) Antimalarials - Primaquine / Pamaquine
  5. b) Antibacterials - Nitrofurantoin
  6. c) Analgesics - Aspirin
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15
Q

What is the other Rare Cell Enzyme (Metabolic Pathway) Erythrocyte Genetic Defects?

A

Pyruvate Kinase Deficiency

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16
Q

What is the Function of Haemoglobin?

A

Gas Exchange:
1. O2 to Tissue
2. CO2 to Lungs
Note - Changes with the Oxygen Dissociation Curve

17
Q

What are the Components of Adult Haemoglobin?

A

Haem Molecule +
1. 2 x Alpha Chains
2. 2 x Beta Chains
Note - Alpha / Beta Genes on Different Chromosomes
Note - Normal Adult Haemoglobin: Hb A (AABB) - 97% / Hb A2 (AADD) - 2% / Hb F (AAGG) - 1%

18
Q

What are the Common Haemoglobinopathies?

A
  1. Mutations leading to Structurally Abnormal Globin Chain - HbS (Sickle Cell) / HbC / HbD / HbE / HbOl
  2. Reduced / Absent Globin Chain Production - Thalassaemia (Alpha / Beta / Delta / Gamma)
19
Q

What type of Inheritance are Haemoglobinopathies?

A

Autosomal Recessive:

1: 4 - Normal
1: 2 - Carrier
1: 4 - Affected

20
Q

Where is the Point Mutation in Sickle Cell Disease?

A

Sickle Haemoglobin (HbS) composed of Haem + :

  1. 2 x Alpha Chains
  2. 2 x Beta (Sickle) Chains
21
Q

What is the Consequence of HbS Polymerisation?

A
  1. Red Cell Injury / Cation Loss / Dehydration
  2. Haemolysis
  3. Endothelial Activation / Promotion of Inflammation
  4. Coagulation Activation / Dysregulation of Vasomotor Tone by Vasodilator Mediators
  5. Vaso-occlusion
22
Q

What is the Clinical Presentation of Sickle Cell Disease?

A
  1. Painful Vaso-Occlusive Crises - Bone
  2. Chest Crisis
  3. Stroke
  4. Increased Infection Risk - Hyposplenism
  5. Chronic Haemolytic Anaemia - Gallstones / Aplastic Crisis
  6. Sequestrian Crisis - Liver / Spleen
  7. Reduced Life Expectancy
23
Q

What is the Management of Sickle Cell Disease?

A
  1. Life Long Prophylaxis - Vaccination / Folic Acid
  2. Hydration / I.V. Fluids
  3. Oxygenation / Respiratory Support
  4. Prompt Treatment of Infetcion - Antibiotics
  5. Analgesia - Opiates / NSAID’s
  6. Transfusion - Chest Crisis / Iron Overload / Alloimunusation / Episodic and Chronic
  7. Disease Modifying Drugs - Hydroxycarbamide
  8. Bone Marrow Transplantation
  9. Gene Therapy
24
Q

What is the Pathology of Thalassaemia?

A

Reduced / Absent Chain Production due to Mutations / Deletions.
You normally get 2 Alpha Chains from the Mother, and 2 from the Father, but in this:
1. 1 x Alpha + 2 x Alpha = “a+”
2. 0 x Alpha + 2 x Alpha = “a0”
The Chain imbalance causes Chronic Haemolysis and Anaemia

25
Q

What is the Spectrum of Clinical Severity of Thalassaemia?

A
  1. Homozygous Alpha Zero Thalassaemia (a0a0) - No Alpha Chains = Incompatible With Life
  2. Thalassaemia Major (Homozygous Beta Thalassaemia) - No Beta Chains = Transfusion Dependent Anaemia
  3. Thalassaemia Intermedia (Non-Transfusion Dependent)
  4. Thalassaemia Minor - “Trait” / Carrier State
26
Q

What is the Treatment of Beta Thalassaemia Major?

A
  1. Chronic Transfusion Support
  2. Iron Chelation Therapy
  3. Bone Marrow Transplant

3rd Year - Haematology (10 decks)

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