Blood Physiology Part 4 Flashcards
(30 cards)
What is the Function of platelets?
Play important roles in hemostasis
What is hemostatis?
Hemostasis is a process to prevent and stop bleeding,
meaning to keep blood within a damaged blood vessel
What are most
effective in dealing with injuries in small vessels like arterioles, capillaries, and venules?
Physiological hemostatic mechanisms
What are the 3 steps of hemostasis
- Vascular constriction
- Formation of a platelet plug
- Coagulation
What happens at Hemostasis Step-1:?
Smooth muscle contracts to reduce
blood loss.
What happens at Hemostasis Step-2:?
Platelets form a piug that temporarily seals the
break in the vessel wall.
How does Platelet plug formation happen?
•Collagen and von Willebrand factor are exposed to platelets after the intact endothelium is injured. Platelet adhere to the collagen fibers, and become activated.
•Activated platelets release chemical mediators, ADP and
thromboxane A2 (TXA2), to activate more and more platelets to aggregate together, form a platelet plug
What is intact endothelium?
Intact endothelium is a barrier between platelets and extracellular matrix (collagen and
von Willebrand factor).
What does platelet aggregation depend on?
Platelet aggregation depends on the linking between integrin allbß3 and fibrinogen
What happens at Hemostasis Step-3:?
Fibrinogen become fibrin forming a mesh reinforce the platelet plug.
What is generated in the coagulation to catalyze the transformation of the soluble fibrinogen into fibrin?
Thrombin
How is clot retraction done?
Platelets contain contractile proteins (actin and myosin), and as the platelets contract, they pull on the surrounding fibrin strands, squeezing serum (plasma minus the clotting proteins) from the mass, compacting the clot and drawing the ruptured edges of the blood vessel more closely together.
What is a platelet-induced process that further stabilizes the colt within 30 to 60 minutes after hemostasis?
Clot retraction
Coagulation is a multistep process involves a series of
substances called
clotting factors, or procoagulants.
What are clotting factors, or procoagulants.?
They are inactive plasma protein and will be converted into active
form through an enzymatic cascade.
Most them areproduced in liver.
What does role does the liver play in blood physiology?
The liver plays a critical role in producing and modifying blood- borne proteins, including those used in the clotting pathway.
What do bile salts from the liver facilitate?
the absorption of lipids in the diet, including vitamin K
What is vitamin K required for?
required for the synthesis of prothrombin and several other
clotting factors.
What are the three phases of Coagulation?
Phase 1: Generation of Prothrombin Activator
• Phase 2:Generation ofThrombin
• Phase 3: Generation of Fibrin Mesh
Coagulation may be initiated by either the …………….pathway.
intrinsic or the extrinsic
Why the name intrinsic pathway?
Intrinsic pathway, so named because everything necessary for it is in the blood,
is initiated by factor XII.
Why the name extrinsic pathway?
Extrinsic pathway, so named because a cellular element outside the blood is needed, is initiated by factor Ill (Tissue factor)
Where does the Intrinsic pathway and extrinsic pathway meet?
The two paths merge at factor Xa.,
What happens Once factor X has been activated?
it complexes with Ca2+, PF3, and factor V to form prothrombin activator
