5. Haemostasis & Thrombosis Flashcards
What do vessel walls do in haemostasis?
Constrict to stop blood loss
What are the 4 factors that haemostasis depends on?
Vessel wall
Platelets
Coagulation system
Fibrinolytic system
What do platelets do in haemostasis?
Adhere to damages on vessel wall and to each other to for a platelet plug
What factors does thrombin positively feed back on?
V
VIII
XI
What is coagulation inhibited by?
Anti thrombin III Alpha 1 anti trypsin Alpha 2 macroglobulin Protein C Protein S
What is fibrin broken down by?
Plasmin
What are “clot busting” drugs?
Streptokinase which activates plasminogen
Define thrombosis
Formation of a solid mass of blood within the circulatory system during life
What is Virchow’s triad and what are the 3 factors?
Virchow’s triad are the three main factors that contribute to thrombosis which are:
Changes in blood flow
Changes in vessel wall
Changes in blood components
Name 4 features of arterial thrombi
Pale
Granular
Lines of Zahn
Lower cell content
Name four features of venous thrombi
Deep red colour
Soft
Gelatinous
Higher cell content
Name 2 things that can follow an arterial thrombi
Ischaemia
Infarction
Name 4 things that can follow a venous thrombi
Congestion
Oedema
Ischaemic due to the oedema pressure being greater than arterial pressure
Infarction
What are the 5 main outcomes for a thrombosis?
Lysis Propagation Organisation Canalisation Embolism
Define embolism
Blockage of a blood vessel by a solid, liquid or gas at a site distant from its origin
Name 6 things that can act as an embolism
Thrombi Air Nitrogen Amniotic fluid Tumour cells Medical equipment
Thromboembolisms from the systemic veins usually become emboli where?
Pulmonary system
Thromboembolisms from the heart usually embolise where?
Via aorta to renal, mesenteric and other arteries
An embolism in the carotid artery can lead to which medical condition?
Stroke
What is a paradoxical embolism?
When there is an embolism in the systemic venous system which reaches the systemic arterial system via a patent foramen ovale or ASD
An embolism in the abdominal aorta usually ends up where?
Arteries of the legs
What can a major pulmonary embolism rapidly lead to?
Death
What can recurrent pulmonary embolisms lead to?
Pulmonary hypertension
What are two treatments of DVT and how do they work?
Heparin - cofactor for anti thrombin III
Warfarin - interferes with synthesis of vit k dependant clotting factors
Fat embolisms can be caused by what?
Fractures of long bone (yellow marrow contains fat)
Lacerations of adipose tissue
What heart malfunction can lead to a cerebral embolism?
Atrial fibrillation
Leads to stasis and a thrombus
What is an iatrogenic embolism?
Caused due to medical treatment
How can nitrogen embolisms form and what activity therefore puts people at risk of having them?
Nitrogen bubblers form in the blood upon rapid decompression
People who go diving can get this (“the bends”)
What is disseminated intravascular coagulation?
Pathological response to many diseases where small clots form which use up all the clotting factors
This leads to abnormal bleeding from the skin
Haemophilia type A is an x linked disease which affects which factor?
Factor VIII
Haemophilia type B is an x linked disease that affects which factor?
Factor IX
What is thrombocytopenia?
Where platelet count is below reference range
What are causes of thrombocytopenia?
Failure in production of platelets
Increase in destruction of platelets
Sequestering of platelets
Usually accompanied with leukaemia
