Week 3 - Thrombosis, Embolism And Shock Flashcards
What is the structure of a venous thrombus?
- typical layered structure
- lines of Zahn - alternating layers of platelets and erythrocytes
What is disseminated intravascular coagulation? (Capillaries)
- a rare, life-threatening condition that prevents blood from clotting normally
- blood clots reduce blood flow and can block blood from reaching bodily organs
- This increased clotting can use up the blood’s platelets and clotting factors. Fewer platelets and clotting factors available result in excessive bleeding
- involves both thrombus formation and haemorrhage
What can cause disseminated intravascular coagulation?
Infections, septicaemia, malaria, neoplasms and liver disease
What explains all the factors that promote thrombosis?
Virchow’s triad
3 categories with sub categories
- Abnormalities in the vessel wall
- Abnormalities of blood flow
- Abnormalities of the blood’s constituents
What abnormalities may occur in vessel walls?
- arteries - atherosclerosis, inflammation
- heart - MI, rheumatic endocarditis
- veins - trauma, inflammation, chemicals (sclerosants - irritant substances injected to obliterate varicose veins and glucose - atheroma in diabetes mellitus)
- capillaries - inflammation
What abnormalities of blood flow may occur?
- arteries - turbulence (aneurysms, plaques, spasm)
- heart - AF, aneurysms
- veins - local problem (compression, inactivity), general problem (heart failure, circulatory shock)
What abnormalities may occur with the bloods constituents?
- increased viscosity (polycythaemia, dehydration, chronic hypoxia, polycythaemia rubra vera)
- hyperproteinaemia (multiple myeloma - tumour of plasma cells in bone marrow with accumulation of immunoglobulins in plasma)
- clotting abnormalities (pregnancy - prevents bleeding when placenta detaches, some contraceptive pills, following trauma - liver produces more clotting factors, thrombocythaemia, tumours
What happens to resolve a thrombus?
Fibrinolysis- very common fate
What happens with a thrombus detaches from a vessel wall?
Thromboembolism
Define the term embolism
The transport of abnormal material (solid, liquid, gas) by the blood stream and its impacting in a blood vessel
What are the types of emboli?
Thrombi, fat, gas, tumour material, infective agents, atheroma, amniotic fluid, foreign bodies
What is shock?
A physiological state characterised by a significant, systemic reduction in tissue perfusion, resulting in decreased tissue oxygen delivery and insufficient removal of cellular metabolic product, resulting in tissue injury
-not the same as emotional shock
What is hypovolaemic shock?
- haemorrhage - internal or external
- severe burns
What is cardiogenic shock?
- large acute myocardial infarction
- other acute cardiac disease
What is septic shock?
- endotoxins from both gram -ve and gram +ve bacteria
- both lead to dilation of blood vessels
