Flashcards in MOD Deck (42)
What is fibrous repair? In which populations does it occur? Briefly describe the process
-The replacement of functional tissue with scar tissue
-Permanent cell lines eg myocytes
-Blood clot forms -> granulation tissue as infiltrated by macrophages and fibroblasts -> fibroblasts produce collagen and ECM. Angiogenesis occurs. Cell population falls and collagen increases -> fibrous scar
Briefly describe the process of angiogenesis
-Proteolysis of endothelial basement membrane of existing vessel
-Proliferation and migration of endothelial cells which arrnage themselves into a new vessel following a designated tip cell
-Remodelling and stablisation of new vessel making sure it connects with venous system
What are the constituents of ECM?
What is healing by primary or secondary intention?
-Primary intention = apposed edges with minimal clotting. Epidermis regenerates with minimal contraction
-Secondary intention = large wounds or ulcers -> Epidermis has to regenerate from base up forming a scab. more granulation tissue and fibrous repair -> contraction to make edges meet
Briefly explain what happens in a minor cut in successful haemostasis
-BVs contract to limit blood flow -> Platelets become activated by extrinsic pathway and adhere to the damaged vessel wall and each other and set off a cascade activating other platelets to form a platelet plug and stop the bleeding -> primary haemostatic plug -> more platelets adhere and fibrinogen is converted to fibrin by thrombin causing cross linking of platelets making a stable secondary haemodynamic plug
Name some endogenous proteins which help control the coagulation cascade to prevent thrombosis
-Anti-thrombin III, Protein C and S
What is fibrinolysis? Name an endogenous mediator and how this process is used clinically
-The breakdown of fibrin to control excessive clotting
-tPA (alteplase) or streptokinase
What is thrombosis? What causes it to occur? What is Virchows traid?
-Inappropriate clot formation inside a blood vessel
-Inappropriate activation of the clotting cascade
-Abnormal BVs (atheroma, hypertension, toxins), abnomal consituents (OCP, smoking, surgery, blood disorders) and abnormal flow (stasis, AF, CCF, valvular disease). 2/3 needed for thrombosis
What are the possible outcomes of thrombosis?
-Propagation -> progressive spreas
-Organisation -> lumen remains obstructed but turned to granulation tissue
What is an embolism?
-Blockage of a BV by part of a thrombus which has broken off from a different site (doesnt have to be thrombus)
Give some factors which predispose to DVT