lecture 12: Abnormalities in blood coagulation Flashcards
hemostasis
ARREST OF BLEEDING (BLOOD CLOTTING) from coagulation mechanism
causes of hemostasis
trauma, inflammatory or neoplastic damage, vessel erosion, congenital malformations
balance: maintain blood fluidity, stop flow rapidly when system is compromised to prevent blood loss
factors for proper function of hemostasis
- integrity of small blood vessels (and lining: endothelium)
- adequate number of platelets
- normal amounts of coagulation factors (proteins and factors (Ca ions) in blood)
- normal amounts of coagulation inhibitors
*malfunction can lead to life-threatening hemorrhagic or clotting disorders
things that oppose coagulation
NO, prostaglandin, E-NTPDase1 (platelet inhibitors)
heparin/ thrombomodulin
tissue factor pathway inhibitor
anticoagulants produced by liver:
- antithrombin III (inhibits intrinsic)
- Protein C and S (inactivated factors V and VIII)
*necessary to control/ counterbalance coagulation
blood vessel integrity
damage to endothelium:
1. lack of anticoagulatory factors
2. exposure of underlying connective tissue of endothelium (subendothelial collagen)
- allows platelet adhesion
- activates coagulation mechanism (release of vasoconstriction and coagulation factors)
- allows platelets to accumulate and adhere to injury area via vWF
platelets
small fragments of CYTOPLASM from large precursor cells called MEGAKARYOCYTES
- 10-day survival, removed by macrophages in the spleen
factors that compromise hemostasis (blood clotting)
- abnormal bleeding from FAILURE of small blood vessels to CONSTRICT after tissue injury
- abnormal PLATELET formation
- THROMBOCYTOPENIA (not enough platelets to make plug)
- failure/ absence of coagulation factors (vWD, hemophilia)
causes of abnormal hemostasis
- injury of bone marrow damaging megakaryocytes
- infiltration/ crowding
- liver/ kidney damage
- too much coagulatoin factors (DIC)
abnormal platelets
thrombocytopenia or abnormal platelet function:
- damage to bone marrow
- overconsumption (DIC/TTP)
- autoimmune destruction (ITP)
petechiae:
- a sign you have a platelet problem
- small red or blue spots
- pinpoint-sizes HEMORRHAGES of small capillaries in skin or mucous membranes
- indicative of defective or inadequate platelets
- do not blanch when pressed
- petechiae with fever, in infections such as meningococcemia: dengue hemorrhagic disease
disturbances of blood coagulation
- LIVER DISEASE
- dietary (hypocalcemia (Ca2+) required for enzymatic activation of factors)
- anticoagulant drugs (heparin, coumadin)
- inadequate VITAMIN K (need it for coagulation factor production)
-inadequate absorption of vitamin K (occurs in blockage of the common bile duct by a gallstone or tumour, preventing bile from entering the intestine to promote absorption of vitamin)
-deficiency of plasma coagulation factors
- liberation of thromboplastic material into circulation
- drugs
- genetic disease
hemophilia
deficiency of factor VIII, IX or XI (intrinsic inhibited)
bleeding
von willebrand disease
deficiency of vwF meaning that you can’t form clot (no adhesion of platelets to collagen)
- you also need vWF to maintain VIII level in intrinsic
bleeding
ITP (immune thrombocytopenic pupura)
autoimmune disease against platelets
platelets destroyed by splenic macrophages
bruising and bleeding
thrombocythemia
too many platelets
(too much clotting)
primary: too many produced by neoplasm (myeloid leukemia - bone marrow and blood)
secondary: from another disease/ inflammation
factor V leiden
this is usually anti-coagulatory for protein C and S
mutation = CAN’T INACTIVATE FACTOR V
therefore pro coagulatory and clots
