Blood and Innate Immunity

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Blood and Innate Immunity

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University of Southern California
Bisc 307l - General Physiology
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BISC 307L 1st Edition Lecture 29 Current Lecture Blood  Hematopoiesis o o This is the red bone marrow that is very prevalent in late fetal life but into adulthood the red bone marrow is restricted to the femur, pelvis, and ribs o Various levels of commitment of stem cells  Pluripotent hematopoietic stem cellsgive rise to uncommitted stem cellsgives rise to a fully committed progenitor cell which is no longer a stem cell o Controlled but hematopoietic cytokines  EPO secreted by kidney cells that stimulates production of RBC  TPO stimulates development of platelets  Variety of interleukins that can stimulate a bunch of cell types o The most abundant blood cell is erythrocytes and they have a lifespan of 90- 120 days so there is a substantial production of them all the time The cell type that is being produced at the highest rate is neutrophils- life span small so produced more often  Hemostasis o o Clotting  Blood has to flow freely (viscosity term)  The viscosity cant be too high- too much resistance  The blood should not clot inappropriately  But must have ability to clot  Process of hemostasis (cessation of bleeding)  1. Vasoconstriction- triggered by the damage of smooth muscle cells. This minimizes blood loss. When everything is right blood is only in contact with the endothelium except when damaged and it does.  2. 2 abundant proteins in the layers of the wall- collagen and tissue factor The contact of platelets with collagen and tissue factor triggers clotting. Tissue factor has several names (Coagulation factor 3, thromboplastin). Platelets bind to collagen through integrins and make platelets adhere to collagen and make it become sticky and adhere to each other. This sticky platelets forms the platelet plug which increases the resistance to blood leaking out and decreases the pressure so flow goes down. The stuff oozing out will stop being blood and start being clear serum filtered through the platelet plug.

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