Lange 6. Flashcards
Hematopoisesis
developmental process of all mature formed elements of blood
How many cells are produced by the bone marrow each day?
> 100 billion
What cells are produced at a ratio of 3:1?
3 WBC for every 1 RBC (because shorter half life)
What is the major hormone that stimulates production of erythrocytes? Where is it produced?
erythropoietin: kidneys
What is the feedback system for erythropoietin?
blood hemoglobin levels fall - oxygen delivery to kidneys falls, produce more erythropoietin
What are the most common WBCs?
granulocytes (cytoplasm filled with granules)
Neutrophils
most prevalent granulocyte - most important cell in producing inflammation
Myelopoisesis
granulocyte production
What cytokines are important for granulocyte production? (myelopoisesis)
IL-3, G-CSF, GM-CSF
What is the difference between G-CSF and GM-CSF?
GM-CSF stimulates the maturation of a different WBC lin - monocyte-macrophage line
How are platelets produced?
fragments of megakaryocytic (larger multinucleate cells in the marrow)
What cytokines stimulate platelet production?
IL-3, IL-6, IL-11, thrombopoietin (TPO)
Where is thrombopoietin produced? What does it do?
produced by liver, kidney, skeletal muscle, marrow stroma - stimulates platelet production
How long do erythrocytes function before removed by the spleen?
120 dayss
How do reticulocytes appear on blood smear stained with Wright Stain?
bluer (basophilic) - contain some ribosomes and mitochondria for a few days after nuclei are extruded
Hemoglobin structure
tetramer made of two alpha protein and two beta protein subunits
Hemoglobin A
two alpha and two beta subunits
How do granulocytes appear on blood smear?
nuclei are convoluted and multi lobed with granules in cytoplasm, which contain variety of enzymes, prostaglandins, mediators of inflammation
How do basophils appear on blood smear?
very dark blue granules that obscure the nucleus
When do basophils function?
hypersensitivity reactions - also increased in chronic myelogenous leukemia (CML)
How do eosinophils appear on blood smear?
stain red - bilobed nucleus
When do eosinophils function?
part of the inflammatory response to parasites too large to be engulfed by individual immune cells - also involved in allergic reactions
What is the major function of neutrophils?
major function in tissues - granules contain myeloperoxidase which along with free radical oxygen ions produced by NADPH oxidase kill bacteria
What is the half-life of neutrophils?
8 hours (why so many are made)
How do less mature neutrophils appear?
characteristic horseshoe-shaped nucleus that is not fully lobulated (called bands)
Monocytes lifespan
only ~3 days in circulation before residing in tissues where they phagocytose bacteria
How do monocytes appear on smear?
largest cells - irregular but not multi lobed nuclei and pale blue cytoplasm
How do lymphocytes appear on smear? What is special about their maturation?
appear small but slightly larger than erythrocyte, dark nuclei essentially filled the cell - thin rim of light blue cytoplasm - little to no granules. mature outside the marrow
What is the half-life of platelets?
10 dayss
What happens to platelet count in thrombocytopenia? Why?
half life of platelet decreases because they are consumed in the routine maintenance of vascular integrity
How do platelets contribute to coagulation?
important source of phospholipids and contain important receptors that allow attachment to endothelial cells in order to form platelet plug
What is contained in the cytoplasm of platelets?
dense granules and alpha granules
What is degranulation of platelets?
platelet activation
What initiates platelet activiation?
exposure of platelets to activated blood coagulation factor thrombin, ADP, or collagen
What is released from granules during platelet activation?
ADP and platelet factor four
What happens to platelets after activation?
change shape from discoid to spherical with filopodial extensions and finally to a flat shape that allows coverage of vessel injury
How do immature platelets appear?
Larger than normal platelets
What is the end result of the activated coagulation system
complex of cross-linked fibrin molecules and platelets that terminate hemorrhage
How do most coagulation factors circulate?
enzymes (serine proteases) that remain dormant until needed
How are inactive forms of coagulation factors written?
without annotation (factor II)
How are active forms of coagulation factors write?
signified by the letter “a” (fator IIa)
Where are most coagulation factors made? Exceptions?
liver: exceptions = factor XIII (platelets) and factor VIII (endothelial cells)
What are factors II, VII, IX, X dependent on?
liver enzyme gamma carboxylase which is dependent on vit K (as are protein S and C)
What is the mechanism of warfarin?
anticoagulant that interferes with vit K activity
Primary hemostasis
vasoconstriction and platelet adhesion and activation at sites of endothelial injury - collagen and thrombin activate platelets
Secondary hemostasis
process where fibrin is formed - includes initiation, amplification, and propagation
Initiation of hemostasis
release of TF (thromboplastin) by injured cells acting factor VII (to make TF-VIIa) which activates both factor IX and X. Factor Xa and Va catalyze conversion of prothrombin to thrombin (IIa) which cleaves fibrinogen into fibrin
Amplification of hemostasis
occurs at surface of platelets - thrombin activates platelets and coagulation factors V, VII, and XI found on platelet surface. IX activates IX to IXa which provides supplemental factor IXa at platelet surface
What is factor VIII normally complexed to?
vWF
Propagation of hemostasis
activate platelets recruit other circulating platelets and formation of two major complexes: tenase and prothrombinase
What do the tenase and prothrombinase do?
activate factor X which then forms the prothrombinase complex with factor Va on the platelet surface which forms another complex that catalyzes the cleavage of prothrombin II to thrombin IIa
Factor XIIIa
activated by thrombin - incorporates alpha2-antiplasmin into the clot to protect it from fibrinolytic proteases (further solidifies the fibrin polymer)
Fibrinolysis
the process of breaking down fibrin
Major catalytic enzyme in fibrinolysis
plasmin - serum protease that cleaves fibrin
What catalyzes the formation of plasmin from precursor plasminogen?
thrombin (negative feedback) or tissue plasminogen activator (t-PA)
What are inhibitors of fibrinolysis?
plasminogen activator inhibitor and alpha-2-antiplasmin
TFPI: tissue factor pathway inhibitor
inhibits further activity of factor Xa itself but also prevents Xa from binding to the platelet surface - a check on the coagulation system
antithrombin (AT)
protease inhibitor - physically blocks the action of the serine proteases in the coagulation system (activity enhanced by heparin)
Protein C
activated by thrombin - cleaves factor Va into an inactive form sot hat the prothrombinase complex cannot cleave prothrombin II into thrombin
Protein S
cofactor for protein C - complex also inactivates factor VIIIa