Blood Composition and Function

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Questions and Answers

A patient presents with symptoms indicative of chronic hypoxia and cyanosis. Further investigation reveals a methemoglobin level of 75%. Which of the following interventions is MOST likely to be considered, given the severity and potential lethality of this condition?

Initiating immediate blood transfusions to dilute the methemoglobin concentration.
Administering a high dose of Vitamin B12 to enhance erythropoiesis.
Implementing methylene blue therapy to reduce ferric $$Fe^{3+}$$ iron back to the ferrous $$Fe^{2+}$$ state. (correct)
Prescribing a course of oral iron supplements to facilitate hemoglobin synthesis.

The presence of Howell-Jolly bodies on a peripheral blood smear in a splenectomized patient suggests impaired erythropoiesis.

False (B)

What is the underlying mechanism by which hydroxyurea alleviates the symptoms of sickle cell anemia, and how specifically does it modify hemoglobin?

Hydroxyurea increases the production of fetal hemoglobin (HbF), which interferes with the polymerization of abnormal hemoglobin S (HbS) and reduces sickling.

In the context of disseminated intravascular coagulation (DIC), the presence of ______ fragments, indicative of accelerated fibrinolysis is a hallmark diagnostic feature.

schistocytes Signup and view all the answers

Match the following laboratory findings with their MOST likely associated condition.

Elevated Erythrocyte Sedimentation Rate (ESR) = Temporal Arteritis (Giant Cell Arteritis) Presence of Bence Jones protein in urine = Multiple myeloma Peripheral Smear with Auer Rods = Acute Myeloid Leukemia (AML) Positive Direct Antiglobulin Test (DAT) = Autoimmune Hemolytic Anemia Signup and view all the answers

A researcher is investigating novel targets for therapeutic intervention in myeloproliferative neoplasms. Which of the following molecular mechanisms, if successfully inhibited, would MOST potently reduce the excessive proliferation characteristic of these disorders?

Aberrant activation of tyrosine kinases, such as JAK2. (A) Signup and view all the answers

In hereditary spherocytosis, the primary defect lies in abnormal spectrin tetramer formation, leading to decreased red blood cell deformability and splenic sequestration.

True (A) Signup and view all the answers

Describe the pathophysiology of thrombotic thrombocytopenic purpura (TTP) and specify the role of ADAMTS13 in its etiology, emphasizing how its deficiency leads to microvascular thrombosis.

TTP results from a deficiency in ADAMTS13, a metalloprotease that cleaves von Willebrand factor (vWF) multimers. Deficiency leads to accumulation of ultra-large vWF multimers, causing platelet adhesion, microvascular thrombosis, and subsequent thrombocytopenia and microangiopathic hemolytic anemia. Signup and view all the answers

The diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) is confirmed via flow cytometric analysis demonstrating a deficiency of ______-linked proteins on the surface of blood cells, rendering them susceptible to complement-mediated lysis.

GPI Signup and view all the answers

Match the following coagulation factors with their respective roles in the intrinsic or extrinsic coagulation pathways:

Factor VIII = Intrinsic pathway; cofactor for Factor IXa. Factor X = Common pathway; converts prothrombin to thrombin. Tissue Factor (Factor III) = Extrinsic pathway; initiates coagulation cascade. Factor XII = Intrinsic pathway; activated by contact with subendothelial collagen. Signup and view all the answers

In the management of heparin-induced thrombocytopenia (HIT), which of the following direct thrombin inhibitors is LEAST likely to be affected by renal dysfunction and therefore requires minimal dosage adjustment?

Argatroban (D) Signup and view all the answers

The primary mechanism of action of warfarin involves the direct inhibition of thrombin, thereby preventing fibrin formation.

False (B) Signup and view all the answers

Explain the concept of 'clonal hematopoiesis of indeterminate potential' (CHIP) and its implications in the development of hematological malignancies. Focus on the genes that are most frequently mutated in CHIP.

CHIP involves the presence of somatic mutations in hematopoietic stem cells without meeting diagnostic criteria for a hematological malignancy. Frequently mutated genes include DNMT3A, TET2, ASXL1 etc. CHIP increases the risk of developing myeloid malignancies such as acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Signup and view all the answers

The presence of teardrop cells (dacrocytes) on a peripheral blood smear is often associated with ______ conditions such as myelofibrosis, where distortion of the bone marrow architecture impairs normal hematopoiesis.

myelophthisic Signup and view all the answers

Match the following red blood cell inclusions with their corresponding clinical associations:

Basophilic Stippling = Lead Poisoning or Thalassemia Howell-Jolly Bodies = Splenectomy or Splenic Dysfunction Heinz Bodies = G6PD Deficiency Pappenheimer Bodies = Sideroblastic Anemia Signup and view all the answers

A patient presents with anemia, thrombocytopenia, and recurrent infections. Bone marrow biopsy reveals dysplastic changes in erythroid and myeloid precursors, along with ring sideroblasts. Which of the following chromosomal abnormalities is MOST likely associated with this presentation?

del(5q) deletion. (C) Signup and view all the answers

In the context of heparin-induced thrombocytopenia (HIT), the administration of platelet transfusions is generally considered safe and can effectively counteract the thrombocytopenic effects of HIT.

False (B) Signup and view all the answers

Describe the mechanism by which disseminated intravascular coagulation (DIC) leads to both thrombotic and hemorrhagic complications, and specify the role of plasminogen activators in this process.

DIC involves widespread activation of the coagulation cascade, leading to fibrin clot formation and consumption of clotting factors and platelets (thrombosis). Simultaneously, activation of plasminogen activators, such as tPA, induces fibrinolysis, causing breakdown of clots and subsequent bleeding (hemorrhage). Signup and view all the answers

The underlying molecular defect in sickle cell anemia involves a single nucleotide substitution in the β-globin gene, resulting in the replacement of glutamic acid with ______ at the sixth position, leading to hemoglobin polymerization and red blood cell sickling.

valine Signup and view all the answers

Match the following laboratory findings with their corresponding anemias:

Microcytic, Hypochromic Anemia = Iron Deficiency Anemia Macrocytic Anemia with Hypersegmented Neutrophils = Vitamin B12 (Cobalamin) Deficiency Normocytic Anemia with Elevated Reticulocyte Count = Hemolytic Anemia Anemia with Ring Sideroblasts = Sideroblastic Anemia Signup and view all the answers

Flashcards

What is blood?

The only liquid connective tissue in the body which makes up 8% of our total body weight.

What is Plasma?

The liquid component of blood, making up approximately 55% of the total blood volume; contains water, proteins, electrolytes, and dissolved gases.