Blood and Hemostasis Flashcards
What is serum?
plamsa without blood-clotting proteins
What does plasma contain that serum does not?
fibrinogen
What is the function of fibrinogen?
It causes blood clotting and is a target for thrombin
What is the function of albumin?
to exert major osmotic pressure on blood vessel walls
Where are fibrinogens and albumins made?
the liver
What is an erythrocyte devoid of?
granules and organelles
What are the two major cytoskeletal components of an erythrocyte?
actin and spectrin
What does ankyrin do?
links the spectrin-actin network and the plasma membrane by binding to spectrin and a transmembrane protein.
What kind of transporter is in an erythrocyte membrane?
an anion transporter; it allows HCO3 to cross the plasma membrane in exchange for Cl (allows release of CO2 in the lungs).
What are neutrophils?
components of the blood that phagocytize amoeboids and destroy certain bacterial walls.
What is a basophil?
component of the blood that releases histamine and leukotrienes, which increase vascular permeability and slow contraction of smooth muscles.
What is a eosinophil?
component of the blood that works with basosinophils; it phagocytizes antibody-antigen complexes and parasites.
What is a lymphocyte?
a large round cell that secretes T (cell-mediated immunity) and B (plasma cells) lymphocytes.
What is a monocyte?
a component of the blood that differentiates into osteoclasts or macrophages once it reaches tissue.
What are platelets?
a component of the blood derived from megakaryocytes that participate in aggregation, clot formation, and repair the endothelium with platet plugs.
What substance is released by endothelial cells that decreases platelet aggregation?
prostacyclin
What is the site of synthesis of most of the proteins of the clotting cascade?
the liver
What is hemostasis, and where is it most effective?
The elimination of bleeding small vessels such as capillaires, arterioles and venules.
What is the hemostatic sequence of events in small vessels?
constriction of smooth muscle, constriction of vessels, decreased blood flow, formation of platelet plug, blood clotting (coagulation).
During an injury, what is exposed in the vessel?
collagen fibers; this is what platelets bind to.
When platelets bind to collagen, what is released?
ADP and thromboxane A (stimulates platelet aggregation)
What is von Willenbrand factor?
a plasma protein that adheres platelets to the walls of damaged blood vessels.
What is prothrombin activated by?
Factor XII
When is factor XII activated?
after contact with collaged in the damaged vessel wall.
What is the active form of prothrombin, and what does it do?
thrombin it catalyzes the conversion of fibrinogen to fibrin.
What is fibrin?
a meswork in which platelets, blood cells and plasma become entrapped to form the actual clot. It is activated via thrombin and factor XIII
What protein reshapes a blood clot?
fibrin; it is split into polypeptides by thrombin and activated by factor XIII.
What causes the dissolution of blood clots?
the activation of plasminogen to plasmin; it is also known as finbrinolysis.
What activates plasminogen to plasmin?
t-PA; t-PA and plasmin dissolve the clot.
What is the intrinsic pathway?
The pathway that contains all of the necessary factors in the blood, including calcium (important cofactor).
What is the extrinsic pathway?
The pathway that involves the formation of tissue factor (thromboplastin or factor III).
What factor does factor XII activate in the intrinsic pathway?
factor XI.
Kallikrein is activated by which factor?
Factor XII; kallkrein activates bradykinin, which increases vascular permeability.
Kallikrein is a positive feedback for which factor?
factor XII.
What is the activation for factors IX and X?
11 + thrombin = 9; 9 + 8 (thrombin) + Ca = 10; then common pathway
What is the activation for factors VII and X in the extrinsic pathway?
thromboplastin = 7; 7 + Ca = 10; then common pathway
What mechanism is activated by various cytokines from damaged tissue cells?
leukocytes
What are two phases of leukocyte extravasation?
selectin and integrin phase
What occurs during the selectin phase?
Binding of ligands to P-selections on inflamed tissue causes the leukocyte to roll along endothelium.
What occurs during integrin phase?
Integrin receptors are activated on the membrane and promote transendothelial migration of leukocytes.
What is erythroblastis fetalis?
an antibody condition in which the mother and fetus of the second pregnancy have different antigens.
