Hematopoiesis
& Hemostasis
(1) Hematopoiesis
• Blood Cell Formation
• Occurs in Red Bone Marrow
• Cell Development:
Lymphoid Stem Cell
•Lymphocytes
Hemocytoblast
(original stem cell)
Myeloid Stem Cell
•Erythrocytes
•Basophils
•Eosinophils
•Neutrophils
•Monocytes
•Platelets
(2) Red Blood Cell Development
• RBC’s have no nucleus…
– Synthesize hemoglobin during development
– Increase in hemoglobin  Eject Organelles
– Results in Biconcave Shape
• Erythropoeitin: Protein which controls rate
of RBC production.
– Circulates in blood
– Targets bone marrow
– Produced in liver + kidney
– Decrease in Oxygen  Increase in Erythropoeitin
(3) Rate of RBC Production
(Erythropoeitin Release  More RBC’s)
• Stimulus:
– Change in RBC count
– Change in Oxygen availability
– Change in demand for Oxygen
• Scenario: Decreased RBC count…
– Reduced Oxygen in blood
– Kidney releases erythropoeitin
– Red bone marrow stimulated
– RBC’s produced
(4) Hemostasis (Blood Clotting)
• Stimulus: Injury to blood vessel.
• Events:
1. Collagen fibers exposed, Platelets adhere.
2. Platelets release serotonin to constrict
vessels, More platelets seek wound.
3. Thromboplastin released by damaged
vessel cells.
4. PF3 (Phospholipid) binds with
Thromboplastin + Calcium  BEGIN
CLOTTING CASCADE!
•
Clotting Cascade
(Prothrombin Activator):
1. Prothrombin converted to Thrombin.
2. Thrombin joins Fibrinogen proteins to
form larger polymer (Fibrin).
3. Fibrin forms a mesh-like trap to catch
RBC’s.
4. Vessels Constrict and ruptured edges
are closed together.
Thromboplastin….
Prothrombin….
Thrombin….
Fibrinogen….
Fibrin….
Initial Injury
Clotting Cascade Begins
Prothrombin changed to
Thrombin by Prothrombin
activator
Thrombin binds
with Fibrinogen to
form Fibrin…
Finally the meshlike net is formed
to catch blood
cells
(5) Thrombus vs. Embolus
• Thrombus  Clot in wall of blood vessel
• Embolus  Free Floating Thrombus
• Causes:
– Rough blood vessel tissue from burns, ruptures, fat.
– Slow blood flow (low levels of activity)
• Aspirin: Common over the counter
anticoagulant.
(6) Thrombocytopenia
(Hemostatic Disorder)
• Low platelet count & Slow Clotting Rate
• Typical of bone marrow cancer and/or
radiation patients.
• Caused by damaged liver  Cannot make
clotting factors.
(7) Hemophilia
(Hemostatic Disorder)
• Low Clotting Factor Count & Slow Clotting
Rate
• Either missing Clotting Factor #8 or #9