Platelet Structure and Function

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What is the primary function of the dense tubular system in platelets?

Housing of coagulation factors and adhesive proteins
Sequestration and release of calcium during resting and activation states (correct)
Containment of hydrolytic enzymes for clot resorption
Storage of glycogen and generation of ATP

Which of the following granules contain growth factors, adhesive proteins, and coagulation factors?

Lambda granules
Dense tubular system
Alpha granules (correct)
Delta granules

What is the primary function of lambda granules in platelets?

Sequestration and release of calcium during resting and activation states
Housing of coagulation factors and adhesive proteins
Containment of hydrolytic enzymes for clot resorption (correct)
Storage of vasoactive molecules for platelet activation

Which of the following is the initial step in the hemostatic process involving platelets?

Platelet deceleration and tethering to the injury site (B) Signup and view all the answers

Which of the following granules contain molecules involved in vasoconstriction and platelet activation?

Delta granules (C) Signup and view all the answers

Which of the following structures in platelets houses enzymes involved in glycogen catabolism, oxygen consumption, and ATP generation?

Granulomere (A) Signup and view all the answers

What is the primary function of the microtubules in platelets?

Assist in maintaining the discoid morphology of platelets (C) Signup and view all the answers

Which of the following statements about the open canalicular system (OCS) is correct?

It facilitates the formation of filopodia during platelet activation (B) Signup and view all the answers

Which of the following ultra-structural features of platelets is directly involved in platelet activation and hemostatic plug formation?

Invaginations of the plasma membrane forming demarcation membranes (B) Signup and view all the answers

What is the primary function of the abundant granules present in the cytoplasm of megakaryocytes?

Release of coagulation factors during platelet activation (B) Signup and view all the answers

What is the primary function of the actin and myosin filaments in platelets?

Assisting in platelet movements and retraction during hemostasis (C) Signup and view all the answers

What is the primary function of the glycoprotein molecules (GPs) present in the plasmalemma?

Interacting with vessel wall components and molecules involved in platelet adhesion (B) Signup and view all the answers

Which of the following statements best describes the role of megakaryoblasts in thrombopoiesis?

They are the precursor cells that undergo polyploidization and fragmentation to form platelets. (C) Signup and view all the answers

Which of the following statements about the hyalomere is correct?

It is the peripheral, clear region of the platelet cytosol (D) Signup and view all the answers

During the hemostatic response to injury, which of the following events occurs first?

Platelet adhesion to the exposed subendothelial matrix (A) Signup and view all the answers

What is the primary function of the demarcation membranes in platelets?

Outlining areas of the cytoplasm that will be fragmented to form platelets (A) Signup and view all the answers

Which of the following statements accurately describes the ultra-structural features of mature megakaryocytes?

They contain numerous invaginations of the plasma membrane, forming demarcation membranes. (A) Signup and view all the answers

During platelet plug formation, which of the following events is responsible for the initial adhesion of platelets to the site of injury?

Binding of platelet receptors to exposed subendothelial matrix proteins (D) Signup and view all the answers