T/F: Leukocytes and RBCs drive most blood-mediated inflammatory responses
FALSE
___________ drive most blood-coagulation responses
Platelets
What is the buffy coat portion of blood composed of and what
percentage of whole blood does it take up?
Leukocytes and platelets <1%
List cells in the blood that have a nucleus
Monocytes Neutrophils Lymphocytes
T/F: Platelets have no nucleus, actin, or myosin and therefore cannot
proliferate/synthesize proteins
FALSE
What is the purpose of contractile proteins in platelets?
Clot retraction / platelet aggregation
List 7 things platelets have/produce:
Actin and myosin Contractile ptns ER and
Golgi Mitochondria Eiconsanoids and eiconsanoid
production enzymes Cell surface receptors
Granules
What is the function of the ER and golgi in platelets?
Contain enzymes/ptns and store calcium
What is the function of the mitochondria in platelets?
Forms ADP/ATP
What is an example of an eiconsanoid and eiconsanoid enzymes in platelets?
Thromboxane (TXA1) Thromboxane synthase,
cyclooxygenase
T/F: TXA1 is a very potent vasodilator
FALSE
List examples of cell surface receptors on platelets
GP receptor Serotonin receptor
Protease-activated receptor (PAR) Purinergic
receptor
What is the function of granules in platelets?
Contain serotonin, Ca, enzymes, ADP, and PDGF
What is the overall function of platelets?
Form platelet plug that helps seal breaks in blood vessels
How are circulating platelets kept inactive and mobile?
Endothelium creates slick surface by continuous production of NO and
prostacyclin inhibiting the platelets from sticking
During hemostasis (stopping bleeding), platelets adhere to
____________ and release chemicals that act as ___________ to change
the physical properties of nearby platelets
Collagen fibers; autocoids
Defined as fast series of rxns to stop bleeding
Hemostasis
List the 3 main steps in hemostasis
Vascular spasm Platelet plug formation
Coagulation (blood clotting)
List the triggers for vasoconstriction
Direct injury to vascular smooth muscle Chemicals
released by endothelial cells and platelets Pain
reflexes
T/F: Vasoconstriction is most effective in the aorta and pulmonary arteries
FALSE
Platelet plug formation is a _____________ (positive/negative)
feedback cycle.
Positive
Describe how the platelet plug formation occurs
Damaged endothelium exposes collagen fibers Platelets
stick to collagen via von willebrand factor (by binding to GP
receptor on platelets) Platelets swell, become
spiked/sticky, and release chemical messengers to make nearby
platelets sticky Platelet plug forms
What process reinforces platelet plug formation by initiating the
formation of fibrin threads?
Coagulation
T/F: In platelet plug formation, the blood is transformed from liquid
to gel
FALSE
Which clotting factors need vitamin K in order to be synthesized?
II, VII, IX, and X
During coagulation, ________ forms a mesh that traps red blood cells
and platelets forming the clot
Fibrin
List the important components of platelet activation:
Formation of Thromboxane (through activity of COX)
Release of platelet granules Expression of GPIIb/IIIa
via various receptor activation (i.e. ADP)
List the drugs that inhibit cyclooxygenase
Aspirin
List the important agonists for platelet activation
Thrombin TXA2 ADP
An important transducing mechanism in platelet activation is enhanced
_______ in the platelet
Ca
Glycoprotein receptors are also called:
Integrin receptors
How does PGH2 inhibit aggregation and cause vasodilation through the
epithelial cells?
PGH2 activates PS which synthesizes PGI2
How does PGH2 cause aggregation and vasoconstriction in platelets?
PGH2 activates TS which synthesizes TxA2
How does aspirin decrease aggregation and vasoconstriction of platelets?
Inhibits COX1 = no PGH2 = no TS = no TxA2
List the important contents of the ? granules
Fibrinogen von Willebrand factor (VWF)
List the important contents of the dense granules
ADP ATP Ca
List the PDE inhibitors
Dipyridamole Cilostazol
Aspirin/Dipyridamole
List the inhibitors of ADP-mediated Platelet aggregation
Ticlopidine Clopidogrel Presurgrel
Ticagrelor Cangrelor
List the GPIIb/IIIa inhibitors
Abciximab Eptifibatide Tirofiban
T/F: Inhibition of PDE means cAMP does not get broken down which
leads to an increased level of Ca within the platelet = release
granules, express GPIIb/IIIa, and platelet changes shape increasing SA
FALSE
T/F: Activation of both P2Y1 and P2Y12 is
required for ADP-mediated platelet aggregation to occur
TRUE
P2Y1 is _____ coupled
Gq
P2Y12 is _____ coupled
Gi