NR 507 Midterm Study Guide.

Hematopoiesis: -process of blood cell production -Constant throughout life to replace RBCs that grow old and die, are killed by disease, or are lost through bleeding -Occurs in liver and spleen of fetus -Occurs in bone marrow after birth -2 stages: 1. Proliferation (mitotic division) 2. Maturation (differentiation) -Bone marrow: red (hematopoietic/active) & yellow (fatty/inactive) Hematopoietic stem cells (HSCs)- all blood cells are created from HSCs -signaled to undergo differentiation (by cytokines and chemokines, growth factors) to form RBC, WBC, & platelets • Lymphoid: T cell (T-lymphocyte) & B cell (B-lymphocyte) • Myeloid: Monocyte & Granulocytes (WBCs) • Erythrocyte (RBC) • Megakaryocyte (Platelets) Mesenchymal stem cells-develop into osteoclasts, fibroblasts, & adipocytes clip_ Erythropoietin: -hormone that stimulates erythrocyte production -Secreted by the kidneys in response to tissue hypoxia Erythrocyte: -most abundant cells in the body -primarily responsible for tissue oxygenation -mature erythrocytes lack a nucleus and mitochondria, cannot synthesize protein or carry out oxidative reactions. Cannot divide *anaerobic metabolism only -life span: 100-120 days -contains hemoglobin molecules o Stages: (7-day process) • Hemocytoblast (stem cell) binds with erythropoietin • Proerythroblast- committed to morph into RBC • Erythroblast- ribosome synthesis (2 phases) • Normoblast- Hgb accumulation & nucleus ejection • Reticulocyte –(immature RBC) released into circulation, no nucleus, ribosome, or mitochondria • RBC (after it has been in bone marrow 1-2 days) Hemoglobin: oxygen carrying protein of the erythrocyte -hemoglobin packed blood cells pick up oxygen in the lungs and exchange it for carbon dioxide in the tissues -composed of 2 pairs of polypeptide chains (globins) & 4 colorful iron complexes (hemes) -can carry up to 4 molecules of oxygen Oxyheoglobin- binding of oxygen to Fe in heme molecule, RED Deoxyhemoglobin- reduced hemoglobin, after it releases the oxygen to the tissues, BLUE