Lecture 2 - Blood

Which adaptation maximizes hemoglobin packing in mature RBCs?

• Enlarged nucleus

• Increased mitochondrial density

• Expulsion of nucleus and organelles

• Increased ribosomal content

• Development of phagosomal machinery

Mature erythrocytes produce ATP primarily by:

• Oxidative phosphorylation

• Beta-oxidation of fatty acids

• Anaerobic glycolysis

• Pentose phosphate pathway exclusively

• Autophagy of hemoglobin

Loss of organelles in RBCs causes all EXCEPT:

• Inability to synthesize new proteins

• Inability to perform aerobic respiration

• Loss of capacity to repair membranes

• Increased nuclear transcription

• Shortened lifespan relative to nucleated cells

Erythropoiesis begins with which cell type?

• Mature erythrocyte

• Megakaryocyte

• Hematopoietic (pluripotent) stem cell

• Reticulocyte

• Lymphoid progenitor

Correct committed lineage toward RBC formation:

• Pluripotent → lymphoid → erythroblast → erythrocyte

• Pluripotent → myeloid → erythroblast → reticulocyte → erythrocyte

• Pluripotent → myeloid → megakaryocyte → erythrocyte

• Pluripotent → erythroblast → monocyte → erythrocyte

• Pluripotent → reticulocyte → erythroblast → erythrocyte

Which is the first committed stage toward becoming a red blood cell?

• Erythroblast

• Reticulocyte

• Hematopoietic stem cell

• Myeloid progenitor

• Megakaryocyte

Which of the following is an erythroblast?

• Erythroblast

• Reticulocyte

• Myeloid progenitor

• Megakaryocyte

• Hemocytoblast

Reticulocytes normally remain where until fully mature?

• Bone marrow

• Spleen

• Circulation

• Kidney

• Lymph nodes

High numbers of reticulocytes in circulation suggest:

• Normal bone-marrow activity

• Pathology or severe marrow stress

• Decreased EPO secretion

• Low oxygen sensing

• Liver dysfunction

Which structure(s) are still present in a reticulocyte?

• Small non-functional organelle remnants

• Full nucleus and ER

• Ribosomes for translation

• Functional mitochondria

• Lysosomes for recycling