37 Questions
What triggers platelet shape changes during hemostasis?
Thrombin acting on proteinase receptors
Which molecule is released by activated platelets in the process of degranulation?
Serotonin
What is the role of TXA2 in platelet activation?
Increases GPIIbIIIa receptors affinity
What is the function of COX1 during platelet activation?
Converts arachidonic acid to TXA2
How do platelets begin to adhere better to the underlying sub-endothelium?
Loss of discoid shape and formation of filopodia
Which molecule is NOT released by activated platelets during degranulation?
Thrombin
What initiates platelet aggregation by increasing the GPIIbIIIa receptors affinity?
TXA2
What is the function of the demarcation membranes in platelet structure?
Outline areas of cytoplasm that will be fragmented to form platelets
What is the primary role of the Hyalomere in platelets?
Maintain discoid morphology
Which component of platelets is responsible for exerting haemostatic functions through movements and retraction?
Cytosol
What is the role of the open canalicular system (OCS) in platelets?
Connect to invaginations of plasmalemma for releasing granule contents
Which molecule interacts with vessel wall components and plays a role in platelet adhesion?
Polymorphic glycoprotein molecules
What is the main function of the tubular system in platelets?
Assist in shape change and activation
What is the primary source of platelets in the body?
Megakaryocytes
Which of the following is a characteristic of megakaryocytes?
Extensive Golgi complex
What happens to the nucleus of a megakaryoblast during platelet formation?
It becomes polyploid
Which organelle plays a crucial role in platelet production?
Mitochondria
What is the lifespan of a platelet in the blood?
~10 days
Which feature distinguishes platelets from other blood cells?
Non-nucleated nature
During platelet activation, what is the main function of thrombin?
Initiating platelet degranulation and release of granule contents
What process occurs as a result of platelet plug formation?
Thrombosis
Which organelle is primarily involved in Ca sequestration and release during resting states and activation in platelets?
Dense tubular system
Which type of granules in platelets contain growth factors, adhesive proteins, and coagulation factors?
Alpha granules
What type of molecules are contained in Delta granules in platelets?
Serotonin and ATP
Which organelle in platelets contains hydrolytic enzymes that aid in clot resorption?
Lysosomes (Lambda granules)
During vasoconstriction, which molecules are secreted from Delta granules of platelets?
ADP and ATP
Platelets deaccelerate by tethering within seconds at the site of injury to the vessel wall. Which process do platelets play a role in during the haemostatic process?
Blood coagulation
Which part of the platelet contains a system of enzymes that allow for the catabolization of glycogen and generation of ATP?
Granulomere
Which type of granules in platelets function as lysosomes containing hydrolytic enzymes for clot resorption?
Lambda granules
What is the final step that stabilizes and cement the platelet plug?
Cross-linking and polymerization of fibrin by activated Factor XIII
Which drug inhibits COX1 leading to inhibition of Thromboxane (TXA2) involved in platelet activation?
Thromboxane (TXA2) inhibitors
In platelet aggregation, which receptors bind together via fibrinogen bridges?
GPIIbIIIa receptors
What is the primary haemostatic plug primarily composed of?
Fibrinogen bridges
Which enzyme activates fibrinogen to fibrin during clot retraction and stabilization?
Thrombin
What role does thrombin play in platelet activation?
Activating platelets to secrete granules
Which of the following action is inhibited by Purinergic (P2Y12) Inhibitors used as antiplatelet agents?
ADP binding to its receptors on platelets
'Platelet degranulation' refers to the process where platelets release their:
ADP content
Test your knowledge on the process of platelet adhesion, where glycoproteins bind to collagen and vWF to form a platelet layer, and platelet shape changes triggered by thrombin acting on proteinase receptors. This quiz covers the mechanisms involved in initial platelet activation and adherence to the subendothelium.
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