Deck · USMLE Step 1

Blood, Lymphoreticular & Immune

Hematology and oncology, hemostasis, and clinical immunology — anemias, leukemias, lymphomas, coagulation disorders, hypersensitivity, and immunodeficiencies.

148 cards · audited · SM-2 spaced repetition

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Included with the full USMLE Step 1 program — 14 decks, 1,546 cards.

Sample cards

1

From which precursor cell do all blood cell lineages arise?

The pluripotent hematopoietic stem cell (HSC), which gives rise to common myeloid and common lymphoid progenitors. HSCs are CD34+ and capable of self-renewal.

2

Where does hematopoiesis occur in the fetus versus the adult?

Fetal: yolk sac (3–8 wk) → liver (6 wk–birth, the dominant fetal site) and spleen → bone marrow (begins ~28 wk). Adult: red marrow of the axial skeleton and proximal long bones. Restarting hepatic/splenic hematopoiesis in adults = extramedullary hematopoiesis.

3

Which growth factor drives erythropoiesis and where is it produced?

Erythropoietin (EPO), produced by peritubular interstitial (fibroblast-like) cells of the renal cortex in response to hypoxia (via HIF-1α). It stimulates erythroid colony-forming units in the marrow.

4

What is the normal lifespan of an erythrocyte and how is it removed?

~120 days. Senescent RBCs are removed by macrophages of the reticuloendothelial system, chiefly in the spleen (extravascular hemolysis). Platelets live ~8–10 days; neutrophils only hours to a few days in circulation.

5

Why are mature RBCs entirely dependent on glycolysis for ATP?

They lack mitochondria, so they cannot perform oxidative phosphorylation. ATP comes from anaerobic glycolysis; the HMP shunt supplies NADPH (glutathione defense), and the Rapoport–Luebering shunt makes 2,3-BPG.

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