Week 9 - Clotting and Coagulation Cascade Flashcards
What is hemostasis?
The process by which the body maintains the delicate balance between bleeding and clotting
What are the three layers of the blood vessel?
Intimia –> Inner most
Media –> Thickest in arteries (smooth muscle)
Adventitia –> Thickest in veins (outer most layer)
What is the intimia layer composed of primarily?
Endothelial cells
What is the importance of the endothelial cells in blood vessels?
Synthesize and secrete many mediators in the clotting cascade –> Procoagulants (initiate clots), anticoagulants (inhibit coagulation), fibrinolytics (break down clots)
What mediator secreted and synthesized by the endothelial cells allows platelets to begin sticking to each other?
von Willebrand factor
What does Tissue factor do in regards to the clotting cascade?
Extrinsic –> Tissue factor (3) activates factor 7 –> this 7a can now activate factor X in the common pathway
When vessel injury occurs, what is the first step that takes place?
Endothelial cells secrete Thromboxane A2 and ADP to cause vasoconstriction at the injured site.
What mediators can cause vasodilation of the blood vessel?
Nitric oxide (NO) and prostacyclin
Although the endothelial cells within the intimia secrete many mediators contributing to the clotting cascade, what is another important job this tissue does?
Prevents the fluid contents of the blood from interacting with the sub endothelial space (media) –> This is where highly thrombogenic material is stored, collagen and procoagulants like fibronectin
Where do platelets tend to flow within the blood vessel?
Along the vessel surface –> The endothelial muscle physically repels bigger blood components away (RBCs and WBCs) while smaller components like Platelets get placed conveniently near their site of action
Why is the media layer of the vessel important to coagulation?
Sub endothelial layer –> Secretes collagen and fibronectin which aid in platelet plug formation
What layer of the blood vessel is responsible for the degree of contraction or dilation?
Adventitia –> Outer most layer, thickest in veins
What mediators act of the adventitia vessel layer?
Nitric oxide and prostacyclin –> Dilation
Thromboxane A2 and ADP –> Contraction
Where is nitric oxide and prostacyclin produced?
Endothelial cells
What is the purpose of nitric oxide and prostacyclin in regard to coagulation?
These mediators dilate the vessel, washing away procoagulants and prevents the formation of a clot
Where are platelets formed?
In the bone marrow from megakaryocytes –> They are round and disk like
Normal platelet count and average life span
150 - 300 K, 8 - 12 days
How can platelets participate in anaerobic and aerobic metabolism?
Contains a mitochondria –> Aerobic
Contains glycogen stores –> Anaerobic
What blood cell stores various contractile proteins, enzymes, and large amounts of calcium?
Platelets
Many granules stored within platelets synthesize prostaglandins which _______________
platelets to promote vascular and local tissue reactions
What blood cells can produce thrombin?
Platelets –> Thrombin’s role includes activating coagulation factors as well as recruiting more platelets to the site of injury
Do platelets contain DNA, RNA, or a nucleus?
NO –> So they don’t reproduce
Do platelets float around active?
NO –> Largely inactive until activated by vascular trauma