Examplify 4 Flashcards
mode of action of aspirin
it leads to a reduction in the synthesis of thromboxane A2, meaning reduced platelet aggregation
–> via irreversibly inhibiting cylooxygenase-1
cylooxygenase-1
produces thromboxanes from a arachidonic acid
thromboxane A2
activates platelets
name 3 of the 12 clotting factor now identified by their names or Roman numerals
protein C (factor IV) and thromboplastin (factor III)
most clotting factors are
synthesised in the liver
a 72 year old man develops sudden onset abdominal pain and collapses. On admission he is found to have a leaking AAA. His aneurysm is repaired and he is transfused 10 units of blood. After the operation he is found to be thrombocytopenic. What is most likely explanation for this?
Blood transfusion
- blood stored for more than 24 hours does not contain platelets
in Von Willebrand disease which tests of clotting are most likely to be abnormal?
APTT and bleeding time- both will be raised
Von willebrand disease
due to a deficiency or abnormality in Von Willebrand factor.
Von Willebrand factors has two functions
- it is present in the subendothelilal connective tissue and it assist in platelet plug formation by attracting platelets to the site of the vessel damage
- it also circulates the blood bound to factor VIII, stabilising and delaying the degradation of factor VIII (clotting factor)
Bleeding time
measure of platelet function
APTT
assesses the intrinsic pathway of coagulation, of which VIII is a component
platelet count in Von Willebrand disease
normal, as are PT and INR
PT and INR
measures of the extrinsic pathway
Haemophilia A
deficiency or reduced activity of factor VIII
- insufficient fibrin is produced in haemostats
which of the following is a co-factor requited for effective clotting
calcium copper iodine iron magnesium
calcium
what substances are released by and activate platelets
ADP and thromboxane A2 are released by activated platelets and cause further platelet activation
which substance doesn’t circulate within the blood
fibrin
which molecule requires Vitamin K for its synthesis
prothrombin
which of the following is NOT seen in significant pulmonary embolism
alveolar hypertension impaired gas exchange increased pulmonary vascular resistance right ventricular dilatation systemic hypertension
systemic hypertension
why is systemic hypertension NOT seen in significant PE
systemic hypotension occurs as the vascular obstruction diminishes the venous return to the left ventricle, thereby decreasing its output and causing hypotension
if an embolus found in the right leg has cholesterol clefts which other condition is the pt likely to have
abdominal aortic aneurysm
- contains cholesterol indicating it is likely to have come from an atherosclerotic plaque
- atrial fib and left ventricular aneurysm can result in cardiac thrombi and embolism BUT WONT CONTAIN CHOLESTEROL CRYSTALS.
which is the most common inherited thrombophilia in caucasians
factor V leidon
line of Zahn are only seen in
arterial thrombi
a 74 yr old man present with a painful, pale and cold right food. No pedal pulse can be felt. The signs and symptoms are thought to be due to a thromboembolism. From where is the thromboembolism least likely to have arisen?
AAA Aortic valve Femoral vein Left atrium Left ventricle
femoral vein
