Chapter 14: Blood Flashcards
hemostasis
the stoppage of bleeding
actions that limit/prevent blood loss (3)
- blood vessel (vascular spasm)
- platelet plug formation
- blood coagulation
vascular spasm
- stimulated by cutting/breaking small blood vessel
- smooth mussel in blood vessel contracts rapidly
- slows blood loss quickly, and ends of vessel may close completely
- triggered by stimulation of blood vessel wall, pain receptor reflexes
embolus
blood clot moving through vessels
thrombus
abnormal blood clot in a vessel
thrombosis
blood clot in a vessel supporting vital organ
infarction
death of tissue due to lack of blood supply
atherosclerosis
accumulation of fat in arterial lining
platelet plug formation
- triggered by exposure of platelets to collagen
- platelets adhere to rough surface to form a plug
blood coagulation
- most effective hemostatic mechanism, occurs within 5-15 minutes
- form blood clot in a series of reactions, in which each step activates next one; called a cascade
- initiated by extrinsic or intrinsic
- clotting factors
clotting factors
many chemicals used in blood coagulation
extrinsic clotting mechanism
trigger = damage to blood vessel or tissue
initiation = tissue thromboplastin
reactions = prothrombin activator
conversion = prothrombin to thrombin
fragmentation = fibrinogen to fibrin
intrinsic clotting mechanism
trigger = blood contacts foreign surface
initiation = hageman factor
reactions = prothrombin activator
activator = prothrombin to thrombin
fragmentation = fibrinogen to fibrin
factors that inhibit blood clot formation (5)
- smooth lining of blood vessels
- prostacyclin
- fibrin threads
- antithrombin in plasma
- heparin from mast cells & basophils
smooth lining of blood vessels
prevents activation of intrinsic blood clot mechanism
prostacyclin
inhibits platelet adherence to blood vessel wall
fibrin threads
adsorbs thrombin
antithrombin in plasma
interferes with action of thrombin
heparin from mast cells & basophils
interferes with formation of prothrombin activator
vitamin K
helps to clot blood
antigen
any molecule that evokes an immune response
antibodies
proteins that react against specific antigen
agglutination
clumping of RBC’s; occurs when an antibody encounters its specific antigen
what type of molecule are antigens A & B
carbohydrates
what is blood group based upon?
presence/absence of two major antigens on RBC membranes
blood type A
antigen A, anti-B antibody
blood type B
antigen B, anti-A antibody
blood type AB
antigen A & B, no anti A or B antibody
blood type O
neither antigen A or B, both A & B antibody
type O blood
universal donor
type AB blood
universal recipient
Rh +
presence of antigen D or other Rh antigens on RBC membrane
Rh -
no Rh antigens on RBC membranes
where do anti Rh antibodies form?
only in Rh - individuals in response to presence of RBC’s with Rh antigens
where is there a concern for Rh factor?
pregnant women & fetus
RhoGAM
administered to moms to prevent Rh incompatibility