Hemostasis and Blood Coagulation Flashcards
What is hemostasis?
Prevention of blood loss
What are there mechanisms that prevent blood loss?
Vascular spasm, platelet plug, blood coagulation, and growth of fibrous tissue to close the vessel.
Which mechanism is life saving?
Vascular spasm
What follows vascular spasm in a life saving event?
Platelet
What do blood vessels do all the time?
Regenerate
What are the two main mechanisms that the vascular spasm is responsible for?
Local myogenic and Sympathetic Reflexes cause vascular spasms.
What is local myogenic due to?
in part to serotonin, Ca++ and other vasoconstrictor substances released from injured cells.
Serotonin and Ca++ are examples of what?
Vasoconstrictor substances
In major injury the sympathetic system causes what?
reflexes that generate vascular spasms.
What is part of the autonomic system?
The sympathetic reflexes cause vascular spasms.
Sympathetic reflexes go through the entire body. Is this automatic?
Yes this is automatic.
What is the second major mechanism in injury?
Platelet plug.
The platelet plug is first when?
in minor injuries
A platelet clot, clot smalls holes without what
?
formation of clot
What occurs when a blood vessel is damage in reference to a platelet plug?
Platelets come in contact with the exposed collagen, they swell and become sticky.
Platelets secrete two things to from what?
ADP and Enzymes. Thromboxane a2 (TxA2)
TxA2 will activate what?
Other platelets and can cause a vascular spasm in a small area.
What will cause other platelets to adhere and vasoconstriction to occur?
TxA2
Platelets have a short life time averaging about what?
8-12 days, Avg: 10 days
What are characteristics of platelets?
small, discoid-shaped bodies in the circulating blood of mammals.
What is the principle source of platelets?
bone marrow where the platelets originate from megakarocytes.
What is the function of megakarocytes?
to create platelets
What is the principle role of WBC?
Immunity
What is the principle role of RBC?
carry O2 in the body.
What is the principle role of Platelets?
to assist in the prevention of hemorrhage when blood vessels are injured.
When an area gets injured what occurs?
chemicals are released to signal platelets to come and build up in that specific region.
What is too much turbulence and its effects on platelets?
Too much turbulence is for example high cholesterol. When build up is big and constricts certain pathways this will activate platelets to build up.
What growth factor do platelets contain?
PDGF
What does the growth factor PDGF do?
causes vascular endothelial cells, fibroblasts, and vascular smooth muscles cells to grow.
platelets have a ________ _________ of several plasma proteins.
loose covering
what is factor III?
The membrane phospholipids compose the platelet factors.
What do actin and myosin do?
They are proteins that make platelets stick together and there is a high content of this within platelets.
Platelets contain large amounts of what?
Ca++
Where is ADP and ATP?
in platelets
Factor XIII is responsible for what?
Contain fibrin stabilization factor in the cytoplasm. Final stage when fiber network is formed and make cross linking of fibronetwork.
Platelets can be activated when what is exposed?
collagen
Platelets are also activated when injured cells release what?
ADP, serotonin, and TxA2
The cardiovascular system is lined with what?
endothelial cells with a basement membrane that contain collagen and protein.
What occurs when subendothelial layer is disrupted and collagen gets exposed?
Platelets adhere to it.
What does the platelets adhesion require?
vWF and fibronectin, form sticky projections that permit contact with other platelets.
Aspirin blocks what?
TxA2
When platelets are activated what do they release?
Ca++ from its granule storage into the cytoplasm.
What is the principle messenger for Ca2+ release?
TxA2
TxA2 is the principle messenger for what?
Ca 2+ release
What does Ca 2+ mediates?
release of granular content from the platelets.
What is platelet release reaction?
Ca2+ mediates release of granular content from the platelets.
The extra presence of platelets granules provides what?
High concentration of fibrinogen, fibronectin, and vWF and factor V.
What is high concentration of fibrinogen for?
Need for fibrin and clot formation.
What is the need for fibronectin and vWF needed for?
needed for adhesion.
What is factor V needed for?
thrombin formation
At the end of platelet reactions what occur?
platelets aggregate stick together and form a plug.
Formation of fibrin stabilizes what?
the platelet plug
Receptors on the platelet membrane are exposed to what?
the coagulation factors
A roman numeral system is used for what?
to designate blood clotting factors.
What are the only two factors that are not proteins?
Ca+2 and Phospholipids
What is factor III?
Phospholipids
What is factor IV?
Ca 2+
Why is Ca 2+ necessary?
it is needed for both extrinsic and intrinsic systems. it is a cofactor to cause the reactions to take place.
What is an extrinsic reaction?
it occurs in a catastrophic damage. it will accelerate the speed to up to 10 seconds.
What is intrinsic reaction?
it occurs really slow about 5-6 minutes. Not for major damage.
Factor III phospholipids are in both what?
the extrinsic and intrinsic systems, a phospholipid plays a major role in the formation of the final prothrombin activator.
What is the major role of a phospholipid?
it forms the final prothrombin activator.
What is the extrinsic system incorporate?
Tissue thromboplastin (III), a lipoprotein, and phospholipids.
What are factors that make up the intrinsic system?
it is platelet factor III and factor XII
All of the blood clotting factors except which ones are plasma proteins?
Ca 2+(facor IV) and Factor III
Why is vitamin K necessary?
for the formation of factors II,V,VII,IX,X
What is essential for fibrin formation?
formation of thrombin from prothrombin
In blood coagulation what is going on with the clotting factor?
it circulates in the plasma in inactive form
How does clotting factor get activated?
in a cascade leading to clot formation
Cross-linked fibrin fibers form what?
covalent bonding to increase density and decrease volume.
Plasma serine protease after activation serves as what?
Enzymes triggering further steps in the process
How is clotting mediated?
by the intimate interplay of the intrinsic and extrinsic clotting systems.
With out what will make coagulation go extremely slow?
Ca2+
Ca2+ (IV) acts as what?
a cofactor to cause the reactions to take place.
Intrinsic coagulation reactions occur when?
Preferentially on the platelet surface leading to fibrin formation within and around platelet plugs.
