click below
click below
Normal Size Small Size show me how
chapter 17
blood
Question | Answer |
---|---|
cytoplasmic fragments of megakaryocytes | platelets |
platelets are cytoplasmic fragments of ______ | magakaryocytes |
true or false: normal platelet count is 150,000-400,000 ml of blood | true |
the function of platelets is to form temporary platelet plug that helps seals break in _______ | blood vessels |
circulating platelets are kept inactive and mobile by _____ and prostacyclin from endothelial cells lining blood vessels | nitric oxide |
platelet formation is regulated by ________ | thrombopoietin |
true or false: platelets age quickly and degenerate in about 10 days | true |
hemostasis, the fast series of reaction for stoppage of bleeding requires ______ and substances released by platelets and injured tissues | clotting factors |
platelets stick to ______ that are exposed when vessel is damaged | collagen fibers |
why don't platelets stick to intact vessel walls | because collagen is not exposed |
secreted by endothelial cells that act to prevent platelet sticking | prostacyclins and nitric oxide |
what chemical messengers are released by activated platelets? | ADP and serotinin |
chemical messenger released by activated platelets causes more platelets to stick and release their contents | ADP |
chemical messenger released by activated platelets enhances vascular spasm and platelet aggregation | serotonin and thromboxane A2 |
why is platelet formation an example of positive feedback cycle? | as more platelets stick, they release more chemical, which cause more platelets to stick and release more chemicals |
reinforces platelet plug with fibrin threads | coagulation |
effective in sealing larger vessel breaks | blood clots |
during coagulation _____ is transformed from liquid to gel | blood |
disorder of hemostasis that results in undesirable clot formation | thromboembolic disorder |
disorder of hemostasis abnormalities that prevent normal clot formation | bleeding disorders |
involves both thromboembolic and bleeding disorders | disseminated intravascular coagulation |
clot that develops and persists in unbroken blood vessel may block circulation, leading to tissue death | thrombus |
thrombus freely floating in bloodstream | embolus |
embolus obstructing a vessel | embolism |
pulmonary or cerebral emboli would be an example of which bleeding disorder | embolism |
risk factors: atherosclerosis, inflammation, slowly flowing blood or blood stasis from immbolity | thrombi and emboli |
thrombocytopenia, a bleeding disorder is characterized by a deficient number of _______ | circulating platelets |
thrombocytopenia is due to suppression or destruction of ______ | red bone marrow |
impaired liver function: inability to synthesize ______ (clotting factors) | procoagulants |
causes of ______ include vitamin K deficiency, hepatitis, or cirrhosis | impaired liver function |
liver disease can also prevent liver from producing _____, which is needed to absorb fat and vitamin K | bile |
symptoms include prolonged bleeding, especially into joint cavitites | hemophilia |
widespread clotting occurs in intact ______, blocking blood flow | blood vessels |
disseminated intravascular coagulation | |
_____ antigens are referred to as agglutinogens because they promote agglutination | RBC |
humans have at least _____ naturally occurring RBC antigens | 30 |
erythroblastosis fetalis only occurs in Rh- mom with _____ fetus | Rh+ |
true or false: during secondary pregnancy, Moms anti-Rh antibodies can cross placenta and destroy RBCs of Rh+ baby | true |