HAEMOSTASIS_ME Flashcards
(34 cards)
what are the platelet constituents released during blood vessel injury?
- ADP
- serotonin
- epinephrine
- histamine
which of the following does not happen to bld vessels after injury?
a. local reflex vasodilation
b. release of vasoactive substances
c. platelet adherance to subendothelial collagen fibres
d. “releasing action” of platelet constituents
a.
local reflex vasoconstriction
what does prostacyclin do in haemostasis?
- promotes vasodilation
- ## inhibits platelet aggregation
what is the role of the endothelium in hamostasis?
- procoagulant
- antithrombotic
- thromboresistant
- synthesises von willebrand factor
- synthesises tissue plasminogen activator
- synthesizes collagen
- synthesizes elastin
- synthesizes fibronectin
what is coagulation?
- a process
- generates thrombin
- converst soluble fibrinogen to insoluble fibrin
what is fibrinolysis? what aspects of blood are involved?
fibrinolysis is the breakdown of fibrin
- helps control coagulation’s fibrin formation
- promotes eventual removal of plug to maintain normal blood flow
what are the characteristics of haemostasis?
- interaction of blood vessel wall, adhesive glycoproteins, platelets
- blood coagulation
- fibrinolysis
which is not a source of platelets?
a. bone marrow
b. liver
c. lungs
d. spleen
b
liver.
all others ARE
what can cause increased platelet counts in the splenic pool?
epinephrine-induced splenic contractions from:
- excitement
- fear
- exercise
which is not true of platelets?
a. involved in primary haemostasis
b. anucleated cytoplasmic pieces shed from megakaryocytes
c. cannot synthesize lipids
d. compsed of contractile proteins
c.
yes they can synthesise some lipids that are needed for formation of arachidonic acid
describe platelets on romanovsky stain
- circulating platelets are discoid and anucleated in mammals
- non mammals- fine reddish granules
- equine platelets stain faintly
T/F the platelets have spike like filopods
true
_________ enzyme converts arachidonic acid to ____________
- COX (cyclooxygenase
- prostaglandin
which is not true of thromboxane A2?
a. produced from prostaglandin PGH2
b. potent vasoconstrictor
c. important in primary haemostasis
d. synthesizes phospholipids
d.
doesn’t synthesize phospholipids
what is the circulating lifespan of the platelet?
5-10 days
what cytokine primarily regulates production of platelets?
thrombopoeitin
organize the following in the plateltes response to vascular injury
- aggregation and secretion
- clot retraction
- facilitation and coagulation
- adhesion
- vascular injury
- adhesion
- aggregation and secretion
- facillitation and coagulation
- clot retraction
which is not true concerning the adhesion step in the response of platelets to vascular injury?
a. potassium is involved
b. platelets undergo metamorphysis
c. develop filopodia
d. vWF binds to platelet membrane
a.
calcium is involved
metamorphysis results in greater surface area - filopods
list 2 aggregation agents involved in platelet response to vascular injury
- thromboxane A2
- prostaglandin
what is primary haemostasis?
formation of the primary haemostatic plug after synthesis of thromboxane A2
what are contraindications of using aspirin?
acetylsalicylic acid is an effective inhibitor of platelet aggregation
- inhibits COX1
- inhibits thromboxane A2 (not in bovine)
- so it will cause bleeding, so don’t give to haemorrhagic patients
what is secondary haemostasis?
formation of secondary haemostatic plug
- more stable
- after thrombin formation and the platelet contractile mechanism
which factors are intrinsic pathway?
- factor 12 (hageman factor)
TBC
what two pathways are commonly considered for blood coagulation?
- intrinsic
- extrinsic
