Summary NR 507: MIDTERM REVIEW

Hematology Hematopoiesis: -process of blood cell production -Constant throughout life to replace RBCs that grow old and die, arekilled 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 Erythropoietin: -hormone that stimulates erythrocyte production -Secreted by the kidneys in response to tissue hypoxiaErythrocyte: - 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 moleculeso 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 andexchange it for carbon dioxide in the tissue