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Eicosnoids
Eicosanoids - UTSW
Question | Answer |
---|---|
How are eicosanoids different from steroid hormones? | act locally, created then quickly destroyed |
What do eicosanoids mediate? | inflammatory response, fever, pain, gastric integrity, blood clotting |
What physiologic responses do eicosanoids control? | vasodilation & constriction, platelet aggregation & inhibition, smooth muscle contraction & relaxation |
What is the precursor for eicosanoids? | arachidonic acid |
Where is arachidonic acid stored? | membrane phospholipids |
What are the 3 types of eicosanoids? | prostaglandins, thromboxanes, and leukotrienes |
What is the precursor for arachidonic acid? | linoleic acid (essential fatty acid) |
What regulates amount of eicosanoids? | phospholipase A2 |
What enzyme converts arachidonic acid to leukotrienes? | lipoxygenases |
What enzyme converts arachidonic acid to prostaglandins & thromboxanes? | Cox 1 & 2 (cyclooxygenases) followed by cell specific synthases |
Leukotriene synthesis involves what key intermediate? | 5-HPETE |
Besides leukocytes, what cell is involved in leukotriene synthesis? | platelets |
What 2 signaling mechanisms do eicosanoids use? | autocrine & paracrine |
Which eicosanoid mediates inflammation, fever, plateletaggregation and disaggretation,induce labor, maintain stomach lining? | prostaglandins |
Which eicosanoid is produced by platelets, promoteaggregation (blood clotting) andvasoconstriction | thromboxanes |
Which eicosanoid is produced by mast cells, mediate allergic reactions; SlowReacting Substance of Anaphylaxis(SRS-A), 104X potent than histamineProduced in plasma - smooth musclecell contraction | leukocytes |
Which enzyme is blocked by cortisol/anit-inflammatories? | Phopsholipase A2 |
Wich enzyme is blocked by NSAIDS? | COX 1 & 2 |
Which enzyme is blocked by anti-asthmatics? | lipoxygenases |
Why is aspirin imperfect? | It blocks cox 1 & 2, but cox 1 protects stomach lining via PGE2 |
What are the drawbacks to COX2 inhibition? | Since COX2 (PGI2) inhibits platelet aggregation while COX 1 activates it (TGA2), Inhibiting COX 2 can lead to excess clotting |
How does aspirin prevent heart attacks? | By covalently modifying COX 1 & 2, aspirin leads to their degradation. Since platelets cannot create new cox 1 & 2, this = anticoagulation (however - not all platelets impacted, so some clotting still occurs) |