Physiology LE 2 Practice

Hematopoietic stem cells (HSCs) are defined by which property?

• Produce only erythroid lineages

• Self-renewal and multipotency

• Express CD3 and CD19

• Reside exclusively in the spleen

Erythropoietin (EPO) production is primarily stimulated by:

• Increased PaO2

• Increased 2,3-BPG

• Tissue hypoxia sensed by peritubular fibroblasts in the kidney

• High arterial PO2 sensed in lung alveoli

The most important intracellular regulator of erythrocyte 2,3-BPG synthesis is:

• ATP concentration

• Hemoglobin concentration

• pH and oxygen affinity (via glycolytic control)

• Plasma iron concentration

In iron metabolism, the protein that exports iron from enterocytes and macrophages is:

• Ferritin

• Transferrin

• Ferroportin

• Hepcidin

Hepcidin decreases serum iron by:

• Increasing intestinal iron absorption

• Stimulating transferrin synthesis

• Causing internalization and degradation of ferroportin

• Activating erythropoietin release

Which lab result is most specific for hemolysis?

• Elevated MCV

• Elevated LDH and indirect bilirubin with decreased haptoglobin

• Low reticulocyte count

• Prolonged PT/INR

Reticulocyte count is a direct measure of:

• Bone marrow iron stores

• Recent erythropoietic activity

The major site of platelet adhesion after endothelial injury is:

• Collagen via von Willebrand factor and platelet GPIb

• Fibrinogen via GPIIb/IIIa only

• Plasma fibronectin binding factor IX

• Endothelial ICAM-1

Thromboxane A2 (TXA2) from platelets causes:

• Vasodilation and inhibition of aggregation

• Platelet aggregation and vasoconstriction

• Anticoagulation via protein C activation

• Increased plasminogen activation

Aspirin irreversibly inhibits platelet function by acetylating:

• COX-1 (cyclooxygenase-1)

• COX-2 only

• Thrombin receptor

• ADP receptor (P2Y12)