ANATOMY Unit 3 Notes: Hematopoiesis & Hemostasis

(1) Hematopoiesis The process of blood cell formation and development. All blood cells originate from the stem cell the Hemocytoblast. If it becomes a red blood cell: Hemocytoblast  Erythroid Stem Cell  RBC If it becomes a Lymphocyte white blood cell: Hemocytoblast  Lymphoid Stem Cell  Lymphocyte If it becomes a Non-Lymphocyte white blood cell: Hemocytoblast  Myeloid Stem Cell  Neutrophil, Basophil, Monocyte, Eosinophil

(2) Red Blood Cell Development As red blood cells develop they increase hemoglobin production. Once hemoglobin production reaches maximum, ALL organelles are ejected. This gives red blood cells their biconcave shape. This also means red blood cells contain no nucleus or anything!

(3) Making More RBC’s Red Blood Cells are produced within your bone marrow. Erythropoietin: Protein released from the kidneys which stimulates the production of RBC’s from the bone marrow. Cause for Release of Erythropoietin: Low RBC count Low oxygen levels Body stops producing / releasing erythropoietin when RBC / oxygen numbers are back at homeostasis.

(4) Hemostasis The process of blood clotting. Occurs in 3 Phases: Vascular Phase Goal: Constrict the blood vessels as much as possible to decrease blood flow. Platelet Phase: Goal: Stick platelets to sides of torn blood vessels to patch up hole. Coagulation Phase: Goal: Form the final mesh-net that will full cover the hole and seal up the blood vessels.

(5) The Vascular Phase Blood vessel tears. Serotonin is released from torn vessel cells. Serotonin triggers vasoconstriction of blood vessels. Blood flow temporarily slowed or constricted.

(This begins at the same time as the Vascular Phase.) (6) The Platelet Phase (This begins at the same time as the Vascular Phase.) The same torn vessel cells release Von Willebrand Factor. Free-Floating platelets adhere to Von Willebrand Factor. Adhered platelets release Thromboplastin AND Thromboxane. Thromboxane causes further vasoconstriction of blood vessels.

(7) The Coagulation Phase Pt 1 THE EXTRINSIC PATH Thromboplastin binds with Calcium and Phospholipids. Thromboplastin + Calcium + Phospholipid = “Proconvertin Enzyme” Proconvertin binds with Stuart Prower Enzyme Proconvertin + Stuart Prower = “Prothrombin” THE INTRINSIC PATH Thromboplastin binds with Calcium and Anti-Hemolytic Cofactor. Thromboplastin + Calcium + Anti-Hemolytic Cofactor = “”Prothrombin”

(8) The Coagulation Phase Pt 2 Prothrombin binds with Proaccerin Cofactor. Prothrombin + Proaccerin Cofactor = “Thrombin” Thrombin binds with Fibrinogen. Thrombin + Fibrinogen = “Fibrin”. *Fibrin is the mesh net that finally seals up the wound.

(9) After Coagulation Contractile proteins in platelets bring edges of wound and tissue together to help close up hole. Plasmin Enzyme is slowly released from platelets. Plasmin will begin to degrade clot tissue to help naturally remove scab from the body.