exam deck 10 Flashcards
What are the three main steps in haemostasis?
Vasoconstriction, Platelet Plug Formation, Clotting Cascade.
Why is thrombin crucial in haemostasis?
It converts fibrinogen to fibrin, activates Factor XIII for clot stabilization, and promotes clot retraction.
What role does von Willebrand Factor (vWF) play?
vWF mediates platelet adhesion to the damaged site.
What substances are released by platelets to promote aggregation?
ADP, Thromboxane A2 (TXA2), and Serotonin (5-HT).
What distinguishes the intrinsic and extrinsic pathways?
The intrinsic pathway is activated by internal vessel damage, while the extrinsic pathway is triggered by external trauma exposing tissue factor.
What is the common endpoint of both pathways in the clotting cascade?
Activation of thrombin, which converts fibrinogen to fibrin.
How does calcium contribute to clotting?
It facilitates the activation of clotting factors in the cascade.
How is a clot stabilized after fibrin formation?
Factor XIIIa cross-links fibrin strands, and platelet actin and myosin retract the clot edges.
What happens during clot retraction?
Platelet contraction reduces the wound size by drawing the edges together.
What enzyme is responsible for clot breakdown in fibrinolysis?
Plasmin.
How is plasmin formed?
Tissue plasminogen activator (t-PA) converts plasminogen to plasmin.
What inhibits t-PA activity?
Plasmin Activator Inhibitor (PAI-1).
Name two vasodilators released by intact endothelial cells.
Prostacyclin and Nitric Oxide (NO).
How does heparin prevent clotting?
By activating antithrombin, which neutralizes clotting factors IX-XII.
What is the role of thrombomodulin in anti-coagulation?
It binds thrombin, aiding Protein C and S in inactivating Factors V and VIII.
What does Tissue Factor Pathway Inhibitor (TFPI) do?
Inhibits the Factor VII/tissue factor complex.
How does aspirin affect haemostasis?
It inhibits thromboxane A2 synthesis, reducing platelet aggregation.
What is the mechanism of action of warfarin?
It inhibits Vitamin K-dependent synthesis of clotting factors II, VII, IX, and X.
What are the risks associated with aspirin and warfarin?
Increased bleeding time.
What are the two arms of the immune system?
Innate and Adaptive immunity.
How do innate immune cells recognize pathogens?
Through Pathogen-Associated Molecular Patterns (PAMPs) detected by Pattern Recognition Receptors (PRRs), like Toll-like receptors (TLRs).
Name two key phagocytic cells.
Neutrophils and Macrophages.
What is the function of the complement system?
Tagging pathogens (opsonization), recruiting immune cells, and lysing pathogens with the Membrane Attack Complex (MAC).
What is the role of T helper cells (Th)?
They secrete cytokines to modulate immune responses and help B cells produce antibodies.
What happens during the secondary immune response?
Memory B cells recognize the same pathogen, leading to a faster and stronger response.
What are the main classes of antibodies?
IgM, IgG, IgA, IgE, and IgD.
Which antibody is associated with mucosal immunity?
IgA.
What is a cytokine storm?
A life-threatening overproduction of cytokines in response to infection.
What triggers anaphylactic shock?
Mast cells releasing histamines and other mediators during an extreme allergic reaction.
