HUMAN PHYSIOLOGY Chapter 3 Blood (II) Ying-ying Chen,PhD Dept.of Physiology,Zhejiang University School of Medicine bchenyy@zju.edu.cn
Ying-ying Chen, PhD Dept. of Physiology, Zhejiang University School of Medicine bchenyy ＠zju.edu.cn HUMAN PHYSIOLOGY HUMAN PHYSIOLOGY Chapter 3 Chapter 3 Blood (II)
Physiological hemostasis the arrest of bleeding following injury Three major events: 1.Vascular constriction 2.Formation of a platelet plug 3.Blood coagulation(clotting)
Physiological hemostasis the arrest of bleeding following injury Three major events: 1. Vascular constriction 2. Formation of a platelet plug 3. Blood coagulation (clotting)
1.Vascular constriction Vascular spasm VASCULAR PHASE
1. Vascular constriction
*changes occur in the endothelium at the injury site: Expose collagen Release chemical factors (ADP and tissue factor)and local hormones (endothelins) sBecome "sticky
changes occur in the endothelium at the injury site: \Expose collagen \Release chemical factors (ADP and tissue factor) and local hormones (endothelins) \Become "sticky
2.Formation of a platelet plug Platelet Adhesion Endothelial cell GPIb-IV Platelet Activated platelet) Fibrinogen -receptor Activation Release reaction Platelet Platelet plug Aggregation Fibrin
2. Formation of a platelet plug Fibrinogen receptor Platelet Adhesion Platelet Activation Platelet Aggregation
Positive feedback Platelet Adenosine diphosphate Thromboxane A2 (ADP) Vessel ■ lumen Inhibits platelet Prostacyclin NO Prostacyclin aggregation Normal endothelium Normal endothelium Vessel wall Aggregating Collagen platelet plug Exposed collagen at site of 2001 Beooks/Cole-Thomson Learning vessel injury Figure 11-10 Why does the platelet plug not continuously expand?
Positive feedback Why does the platelet plug not continuously expand? NO
Prostacyclin (PGl2) collagen Phospholipid Phospholipase A2 Arachidonic Acid Cyclooxygenase PGG2 PGH2 Thromboxane synthase Prostacyclin synthase (Platelets) (Vascular endothelium) PGL Aggregation Anti-aggregation Contraction Relaxation
Prostacyclin (PGI2) Phospholipid Arachidonic Acid Phospholipase A2 TXA2 Cyclooxygenase PGG2 & PGH2 PGI2 Prostacyclin synthase (Vascular endothelium) Thromboxane synthase (Platelets) Aggregation Anti-aggregation Contraction Relaxation collagen
3.Blood coagulation transformation of blood from a liquid into a solid gel by changing fibrinogen to an insoluble polymer(fibrin) Clot Activated platelet Fibrin RBC Fibrin
3. Blood coagulation transformation of blood from a liquid into a solid gel by changing fibrinogen to an insoluble polymer (fibrin)
Clotting factors CopyrightThe McGraw-Hill Companies,Inc.Permission required for reproduction or display. Official Designations for Clotting TABLE I2-13 Factors,Along with Synonyms More Commonly Used Factor I(fibrinogen) Factor Ia(fibrin) Factor II(prothrombin) Factor Ila(thrombin) Factor III(tissue factor,tissue thromboplastin) Factor IV(Ca2+) Factors V,VII,VIII,IX,X,XI,XII,and XIII are the inactive forms of these factors;the active forms add an"a"(e.g.,factor XIIa).There is no factor VI. Platelet factor(PF)
Clotting factors
Coagulation cascade Vessel damage Exposure of blood to subendothelial tissue Inactive plasma protein Enzyme Cascade of plasma enzyme activations Inactive plasma protein (requires activated platelets,plasma Enzyme cofactors,and Ca2) Prothrombin Thrombin X川 Fibrinogen Xilla Loose fibrin Stabilized fibrin
Coagulation cascade