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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 |