Stephen's Deck: Hemostasis and Coagulation (Exam III) Flashcards
Coagulation proteins are typically found in what form?
- inactivated form
If the endothelium becomes damage or is injured what does that cause?
- platelet and coagulation process are activated
What are the three layer of a blood vessel?
- Intima → endothelial layer
- Media → subendothelial layer (middle)
- Adventitia → outer layer
Which clotting factors belong to the intima (endothelial) layer?
- VWF
- Tissue factor
- Prostacyclin
- Nitric oxide
These mediators will help with clotting and vascular tone of the vessel
Which clotting factors belong to the Media (subendothelial) layer?
- Collagen
- Fibronectin
How do the endothelial cells of the intima modulate hemostasis?
Synthesize and secrete:
* Procoagulants (initiators of coagulation)
* Anticoagulants (inhibitors of coagulation)
* Fibrinolytics (to dissolve the clot)
Which two vascular mediators are released by the Intima endothelial cells?
- Vasoconstrictors (TXA2, ADP, 5-HTP)
- Vasodilators (NO, prostacyclin)
What jobs do vWF and Tissue Factor(TF) perform on the endothelial layer?
- vWF → help platelets adhere to subendothelial layer
- TF → activates clotting cascade when vessel is injured
Which mediators that are released by the endothelial cells cause vasoconstriction? Which cause vasodilation?
- Constrict → thromboxane A2 and ADP
- Dilate → NO prostacylin
What are the functions of the following Procoagulants:
* Coagulation factors
* Collagen
* vWF
* Fibronectin
* Thrombomodulin
- Coagulation factors → coagulation
- Collagen → tensile strength
- vWF → adhesion
- Fibronectin → mediate cell adhesion
- Thrombomodulin → regulate anticoagulation path
What are the functions of the following Anticoagulants:
* Antithrombin IlI
* Tissue pathway factor inhibitor(TFPI)
- Antithrombin IlI →Degrades factors XII XI X IX II
- TFPI →Inhibits TF
What are the functions of the following Fibrinolytics:
* Plasminogen
* tPA
* Urokinase
- Plasminogen →Converts to plasmin
- tPA →Activates plasmin
- Urokinase →Activates plasmin
Besides vasodilation what other function does Prostacyclin provide?
- inhibit aggregation
- VSM relaxation (duh)
Which layer of a blood vessel is extremely thrombogenic and very active?
- Media (subendothelial)
Which two substances does the media contain that play important roles in clotting? What does each substance do?
- Collagen → potent stimulus for platlet attachement to vessel wall
- Fibronectin → Facilitate anchoring of fibrin during hemostatic plug formation
How does the adventitia control blood flow?
- Influences the degree of vessel contraction via NO and prostacyclin
How does vasodilation of the adventitia limit the activity of procoagulant mediators?
- ↑ BF washes the procoagulants away
Briefly explain how NO enables vasodilation.
- Nitro Oxide Synthase converts L-arginine to NO in the endothelium
- NO diffuses into VSM and activates soluble guanylate cyclase (sGC)
- sGC activates GTP to be converted cGMP, which then causes VSM relaxation
What are Eicosanoids?
- PGs and other compounds such as:
- Prostacyclin
- Leukotriene
- Thromboxane
What are the 4 phases of Hemostasis and Coagulation?
- Vascular phase (Vascular spasm)
- Primary hemostasis (Formation of platelet plug)
- Secondary hemostasis (Coagulation and formation of fibrin)
- Fibrinolysis (Lysis of clot)
What happens during the Vascular Phaseof hemostasis and coagulation?
- Damaged blood vessels cause vascular spasm of smooth muscle in vessel wall
- Localized to the injured area
What are the primary hormones involved in the Vascular Phase of hemostasis and coagulation? What do they do?
- Endothelins → stimulate VSM and cell division of endothelial smooth muscle and fibroblast cells which help repair damaged site
Vasospasm MAY slow down/stop bleeding depending on what?
- BP
What phase occurs after vascular contraction causes tamponade?
- Primary hemostasis
What two things occur during Primary Hemostasis?
- Injured blood vessel attracts platelets
- Initiates the phases of platelet formation
What are the three phases of platelet formation?
- Adherence
- Activation
- Aggregation
What effect causes the platelet circulating in the blood to be positioned near the vessel wall?
- Platelets are smaller than RBCs/WBCs and get pushed to the sides of the vessel
What shape do platelets have that allow them to circulate freely in the blood?
- They are round and disk-like
Where are platelets formed?
- in the bone marrow from megakaryocytes
According to our class what is the normal concentration of platelets in the blood? How long do they live?
- 150000 to 300000 /mm3
- 1-2 wk lifespan
Which 2 systems clears old platelets from the blood? How much of the circulating platelets are stored in the spleen?
- Macrophages in the reticuloendothelial system
- Spleen
- Spleen holds about 1/3 of circulating platelets for later use
In general what do the glycoproteins on the external membrane of the platelet do? What about GpIb and GpIIb-IIIa?
- Adheres to injured endothelium collagen and fibrinogen
- GPIb → attaches platelet to vWF
- GPIIb-IIIa → links activated platelets together to form plug