Coagulation Flashcards
What are the three layers of a blood vessel?
Intima, Media, Adventitia
What type of cells make up the intima?
primarily endothelial, some elastic and connective tissue
Which type of blood vessels (arteries, veins, capillaries) only have intima?
capillaries
Which layer of blood vessels are made up of smooth muscle, collagen and elastic tissues?
media (middle)
Disruption of which tissue type activates the clotting cascade?
collagen
What does collagen do to platelets during the coagulation cascade?
anchor platelets to the vasculature wall
Which layers of blood vessels are under the influence of vascular mediators?
media and adventitia
What is the outer layer of blood vessels, made up of connective and elastic tissue?
adventitia
What are the two functions of endothelial cells?
separates fluid from highly thrombotic material that lies beneath
synthesize and secrete procoagulants, anticoagulants, fibrinolytics
What are the procoagulants, anticoagulants, fibrinolytics secreted by endothelial cells?
Von Willebrand Factor, Tissue Factor
Tissue Factor Pathway Inhibitor
TPA, Urokinase
What does Von Willebrand factor do when secreted from endothelial cells?
adheres platelets to the subendothelial layer
What does tissue factor do when secreted from endothelial cells?
activates the clotting cascade
What does tissue factor pathway inhibitor do when secreted from endothelial cells?
aids in suppression of coagulation
What are TPA and Urokinase, and what do they do when secreted from endothelial cells?
Fibrinolytics.
activate plasminogen and initiates the process of fibrinolysis
When there is disruption to the endothelial lining, what happens to the vessel wall?
Contracts
What are the 4 mediators of vessel tone?
Thromboxane A2 and ADP
Nitric oxide and Prostacyclin
What does Thromboxane A2 and ADP do to the vessel wall?
Vasoconstricts, released from platelets
What does Nitric oxide and Prostacyclin do to the vessel wall?
Vasodilation. Released from surrounding endothelial cells to divert blood flow to other areas.
Where are platelets formed?
megakaryocytes in bone marrow
Hemostasis is not possible without an adequate number of what?
platelets
How do platelets arrive at the site of injury so quickly?
They flow towards the edges of blood vessels due to their size.
Why aren’t platelets constantly clotting blood vessels?
they are largely inactive until stimulated by trauma or plaque disruption
How are platelets different from whole cells?
Both contain mitochondria, actin, myosin. Platelets do not contain a nuclei and cant reproduce
What do platelets produce that activates other platelets to facilitate clumping?
thrombin
What do the alpha and dense granules in platelets do?
store proteins and non proteins, synthesize prostaglandins promoting vascular and tissue reactions
What are the three steps to clot formation/platelet plug?
Adhesion, Activation, Aggregation
What occurs during Adhesion stage?
vWF attaches to Gp1b receptors on the platelet surface.
What does vWF do to strengthen the forming clot?
attracts more platelets to the site of injury and increases their adhesion ability (stickiness)
What occurs during the Activation stage?
Platelets undergo conformation change to activated form
What is the conformational changes platelets undergo during activation?
Disk to oval
Develop spiky protrusion to aid in stickiness
During Activation: what are the 2 mechanism that activate phospholipase C?
Platelet binding to vWF initates “outside in” signaling to activate phospholipase C
Tissue factor, thrombin, ADP, TxA2 stimulate GPCR that signal more activation of phospholipase C
During Activation, what are the two things actually responsible for changing the shape of platelets?
Phospholipase C and calcium