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Platelets
Overview
60
Anatomy
Undergraduate 1
02/28/2013

Additional Anatomy Flashcards

 


 

Cards

Term
Are platelets types of cells
Definition
No - they are fragments of marrow cells called megakaryocytes
Term
Megakaryocytes
Definition
Marrow cells - platelets are fragments of these types of cells
Term
The second most abundant formed element
Definition
Platelets
Term
Do platelets have nuclei
Definition
No
Term
Platelets secrete these types of chemicals
Definition
Vasoconstrictors, procoagulants, chemicals that attract neutrophils and monocytes to inflammation, growth factors
Term
The reason why platelets secrete growth factors
Definition
To stimulate mitosis in fibroblasts and smooth muscle - help maintain and repair blood vessels
Term
Thrombopoiesis
Definition
The production of platelets
Term
Some PPSCs produce receptors for this type of hormone, which causes it to become a megakaryoblast
Definition
Thrombopoietin
Term
True or false - a megakaryoblasts duplicate DNA without undergoing nuclear or cytoplasmic division
Definition
True
Term
Megakaryoblasts duplicate their DNA to form this
Definition
A megakaryocyte (giant cell)
Term
Megakaryocytes live here
Definition
Red bone marrow - adjacent to blood-filled spaces called sinusoids
Term
Sinusoids are lines with this type of cells
Definition
Squamous celled epithelium called endothelium
Term
Megakaryocytes sprout these, which pass through endothelium and into the blood of the sinusoid
Definition
Tendrils (proplatelets)
Term
What happens after megakaryocytes sprout tendrils (proplatelets) into the blood of sinusoids
Definition
Blood flow sheers of the tendrils (proplatelets) that become platelets
Term
25-40% of platelets live here
Definition
Spleen
Term
The length of time that platelets live circulating in the blood
Definition
10 days
Term
Haemostasis
Definition
Causing blood to stop
Term
The three haemostatic mechanisms
Definition
Vascular spasm
Platelet plug formation
Blood clotting (coagulation)
Term
Coagulation
Definition
Blood clotting
Term
First mechanism in haemostasis
Definition
Vascular Spasm
Term
Second mechanism in haemostasis
Definition
Platelet plug formation
Term
Third mechanism in haemostasis
Definition
Blood clotting (coagulation)
Term
Main action that occurs during vascular spasm
Definition
Swift contraction of blood vessels
Term
The action of pain receptors during vascular spasm
Definition
Some innervate nearby blood vessels and cause them to constrict
Term
Chemical released by platelets due to injury of smooth muscle of a blood vessel
Definition
Serotonin - a chemical vasoconstrictor - causes longer lasting vasoconstriction
Term
The reason why platelets do not adhere to endothelium
Definition
They are smooth and coated with prostacyclin (a platelet repellent)
Term
The platelet repellent that coats endothelium
Definition
Prostacyclin
Term
What platelets adhere to when endothelium is broken
Definition
Collagen fibres that become exposed, and rough surfaces
Term
These fibres are exposed when endothelium is broken
Definition
Collagen fibres
Term
Platelets grow these to adhere to blood vessels and other platelets
Definition
Pseudopods - long and spiny
Term
Pseudopod
Definition
A temporary projection of the cytoplasm of certain cells
Term
This causes the walls of blood vessels to draw together during platelet plug formation
Definition
Pseudopods contract
Term
Serotonin, ADP, and thromboxane A2 are released by what
Definition
Platelets that are undergoing degranulation
Term
Degranulation
Definition
Exocytosis of cytoplasmic granules and release of factors that promote homeostasis
Term
The role of serotonin
Definition
A vasoconstrictor
Term
The role of ADP in haemostasis
Definition
Attracts more platelets to area and stimulates degranulation
Term
The role of A2 in haemostasis
Definition
It is an eiconsanoid - promotes plateletaggregation, degranulation, and vasoconstriction
Term
The main objective of coagulation
Definition
To convert fibrinogen into fibrin
Term
What type of molecule is fibrinogen
Definition
A plasma protein
Term
The two reaction pathways of coagulation
Definition
Intrinsic and extrinsic
Term
The type of factors that initiate the extrinsic mechanism of coagulation
Definition
Clotting factors released by damaged blood vessels and perivascular tissues
Term
The type of factors that initiate the intrinsic mechanism of coagulation
Definition
Only factors found in blood
Term
The name given to clotting factors
Definition
Procoagulants
Term
The lipoprotein mixture released by damaged blood vessels and perivascular tissue that initiates coagulation
Definition
Tissue thromboplastin (factor III)
Term
The next step in the completion of coagulation, after factor X has been activated
Definition
Factor X combines with factors III and V in presence of Ca2+ and PF3 - produces thrombin activator
Term
The effect of thrombin on fibrinogen
Definition
Chops up fibrinogen into shorter strands of fibrin - becomes a dense aggregation called a fibrin polymer (framework of blood clot)
Term
Which mechanism of coagulation has fewer steps to activate factor X
Definition
Extrinsic mechanism
Term
Platelets and epithelial cells secrete this to stimulate cells to repair damaged blood vessels
Definition
Platelet-derived growth factor (PDGF) - a mitotic stimulant
Term
The type of chemical that platelet-derived growth factor is
Definition
A mitotic stimulant
Term
Fibrinolysis
Definition
The dissolution of a blood clot
Term
The role of plasmin
Definition
It is a fibrin dissolving enzyme
Term
This plasma enzyme converts inactive protein plasminogen into plasmin
Definition
Kallikrein
Term
True or false - Thrombin can activate plasmin
Definition
True
Term
True or false - Plasmin indirectly promotes the formation of more kallikrein
Definition
True
Term
The three things that prevent inappropriate clotting
Definition
Platelet repulsion, Dilution, Anticoagulants
Term
What chemical is normally too diluted in blood to make it clot inappropriately?
Definition
Thrombin
Term
The anticoagulants present in plasma that stop thrombin forming inappropriate clots in the blood
Definition
Antithrombin, Heparin
Term
Antithrombin is secreted from here
Definition
The liver
Term
The role of heparin
Definition
Interferes with promotion of prothrombin activator, blocks action of thrombin on fibrinogen and promotes action of anti fibrinogen
Term
Heparin is secreted by these
Definition
Basophils and mast cells
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