Otterbein/Grant CRNA A&p Hemostasis/Coagulation Quick Review

Goal of maintaining production is to assist w/oxygenation w/o increasing the viscosity of blood
Increased production w/hypoxia
Decreased w/chemo, radiation, low Fe intake

Also carry carbonic anhydrase - 70% of buffering capacity of body

vWF is not synthesized in the liver but by endothelial cells and megakaryocytes
Also: calcium and tissue factor not synthesized in the liver

Fibrinolysis is the process of converting plasminogen to plasmin, which helps in dissolving clots and restoring normal blood flow through the vessels. This process is essential for maintaining the integrity of the circulatory system and preventing blockages that can lead to serious complications. Clot formation and gluconeogenesis are unrelated processes and not relevant to the given explanation.

The extrinsic pathway is activated when there is an injury outside the blood vessel or vessel wall. This pathway is initiated by the release of factor III, also known as tissue factor, which is present in surrounding tissues. Once activated, the extrinsic pathway leads to the formation of a blood clot to stop bleeding.

The reticuloendothelial system and spleen are responsible for removing aged platelets from the bloodstream. Platelets have a limited lifespan and as they age, they become less effective in their functions. The reticuloendothelial system, which includes macrophages and other immune cells, recognizes and engulfs these aged platelets, clearing them from circulation. The spleen also plays a role in filtering and removing old or damaged platelets. Therefore, the statement that aged platelets are removed by the reticuloendothelial system and spleen is true.

Following endothelial injury and vasoconstriction caused by thromboxane A2 and ADP:

vWF emerges from endothelin
Glycoprotein Ib receptors emerge from platelets and attach to vWF – attracting platelets to lining of vessel
vWF makes platelets sticky and adhere to site of injury

Factor IV, also known as calcium, plays a crucial role in both the intrinsic and extrinsic pathways of blood coagulation. In the intrinsic pathway, calcium is required for the activation of factor IX, which is a key step in the clotting process. In the extrinsic pathway, calcium is necessary for the activation of factor VII, which is also essential for clot formation. Therefore, the presence of factor IV (calcium) is indeed necessary for both pathways to proceed, making the statement true.

Platelets are indeed formed in the megakaryocytes, which are large cells found in the bone marrow. These megakaryocytes undergo a process called fragmentation, where they break apart and release small fragments known as platelets into the bloodstream. Platelets play a crucial role in blood clotting and preventing excessive bleeding. They have a lifespan of about 8-12 days before being removed from the circulation. A normal platelet count in the blood is typically between 150,000 and 300,000 platelets per cubic millimeter (mm3). Therefore, the statement "Platelets are formed in the megakaryocytes, have an 8-12 day lifespan, and a normal platelet count is 150-300,000/mm3" is true.

Tissue factor is a protein that plays a crucial role in initiating the blood clotting process, also known as coagulation. When tissue damage occurs, tissue factor is released, activating a cascade of reactions that ultimately leads to the formation of a blood clot. Therefore, tissue factor can be considered the trigger for coagulation to occur.

The average lifespan of a red blood cell (RBC) is 120 days. This means that on average, a red blood cell will circulate in the body for approximately 120 days before being removed and replaced by new cells.

The statement is true because NSAIDs (Nonsteroidal anti-inflammatory drugs) inhibit the synthesis of thromboxane, which is a chemical that promotes platelet aggregation and blood clotting. By inhibiting thromboxane synthesis, NSAIDs reduce platelet function and can lead to bleeding. This is why bleeding is a potential side effect of NSAID use.

Plasminogen is a precursor protein that is activated by tPA, urokinase, and streptokinase to form plasmin. Once activated, plasmin acts on fibrin, breaking it down into smaller fragments called fibrin degradation products. This process is important for the dissolution of blood clots and the regulation of fibrin deposition in the body.

Evaluated by PT & PTT

Prostacycling is a powerful vasodilator, meaning it causes the blood vessels to widen and relax. It is derived from arachadonic acid and synthesized by endothelial cells. This dilation of blood vessels helps to increase blood flow and reduce blood pressure.

Prostacyclin is produced under normal conditions. Prostacyclin is a prostaglandin that is synthesized by the endothelial cells lining blood vessels. It plays a crucial role in maintaining normal vascular function by inhibiting platelet aggregation and promoting vasodilation. On the other hand, thromboxane is produced in response to vascular damage or injury and promotes platelet aggregation and vasoconstriction.

During the amplification/propagation phase of the cell-based theory, various factors such as platelet activation, coagulation factors, and cell-surface receptors work together to enhance and amplify the production of thrombin. Thrombin is a crucial enzyme that plays a central role in the conversion of fibrinogen, a soluble protein, into fibrin, an insoluble protein. This burst of thrombin is necessary for the formation of a stable blood clot, which is essential for hemostasis and wound healing.

ATIII, protein C, protein S, and tissue factor pathway inhibitor are all internal anticoagulants. These substances play a crucial role in regulating the coagulation process and preventing the formation of blood clots. ATIII inhibits the activity of thrombin and other coagulation factors, while protein C, protein S, and tissue factor pathway inhibitor inhibit the formation of thrombin. By inhibiting or regulating these clotting factors, these internal anticoagulants help maintain the balance between clotting and bleeding, preventing excessive clot formation and reducing the risk of thrombosis.

Causes vascular vasodilation, limiting procoagulant mediators by washing them away.

Both granules synthesize prostaglandins

Cryo, also known as cryoprecipitate, is a blood product that is rich in clotting factors. It is used to treat bleeding disorders and contains factors I, VIII, XIII, vWF, and fibrinogen. However, tissue factor is not present in cryo. Tissue factor is a protein that plays a crucial role in initiating the clotting cascade, but it is not included in cryo.

Erythropoietin is a glycoprotein that is produced in response to low oxygen levels in the blood (arterial hypoxemia). It is released from the kidneys and acts on the bone marrow to stimulate the production of red blood cells. This process takes around 5 days to reach its peak, but will continue until the hypoxemia is resolved.

Thromboxane A2 is a potent vasoconstrictor that causes platelet aggregation. Inhibiting adenylyl cyclase and cAMP would prevent the activation of platelets and the formation of thromboxane A2, thereby reducing vasoconstriction and platelet aggregation.