Eicosanoids Flashcards

1
Q

What is the main function of eicosanoids?

A

They play critical roles in inflammation, the vasculature and in gastrointestinal, reproductive, renal and respiratory function

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2
Q

What are the 4 types of eicosanoids?

A

-prostoglandins
-thromboxanes
-leukotriens
-lipoxins

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3
Q

How do eicosanoids function?

A

They act as local hormones with very short half lives, functioning mostly through G-protein-linked receptors

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4
Q

What are the fatty acid precursors of eicosanoids?

A

essential fatty acids: linoleic acid or alpha linolenic acid
or directly from arachidonic acid

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5
Q

What are the two enzymatic pathways of eicosanoid synthesis?

A

cycloocygenase
lipoxygenase

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6
Q

Which pathway yields which type of eicosanoid?

A

-cycooxygenase: prostaglandins and thromboxanes
-lipoxygenase: leukotrienes and lipoxins

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7
Q

Which enzyme is associated with arachidonic acid derived eicosanoids?

A

cycloocygenase (COX) 1 & 2

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8
Q

What is the difference between COX 1 and COX 2

A

COX-I is in many cell types, and is responsible for normal housekeeping functions, homeostasis, regulation of blood flow to the kidney and GI tract
COX-2: expressed in inflammatory cells

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9
Q

What are cyclooxygenase products?

A

Prostaglandins H2 which is converted to PGD2, PGE2, TXA2, TXB2, prostacyclin (PGI2)

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10
Q

What is the function of prostacyclin (PGI2)?

A

vasodilation, increase renal blood flow, bronchodilation, inhibits platelet aggregation

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11
Q

What is the function of PGE2?

A

decrease gastric acid secretion, renal blood flow and vasodilation, uterine contraction, GI smooth muscle contraction

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12
Q

What is the function of PGF2alpha

A

uterine contration, bronchoconstriction

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13
Q

How do NSAIDS function?

A

They inhibit cyclooxygenases

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14
Q

What is the main function of thromboxane A2?

A

opposes prostayclin (PGI2), vasoconstriction and encourages platelet aggregation

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15
Q

Where are lipoxygenases produced?

A

white blood cells, lung, immune cells

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16
Q

What reaction does lipoxygenases catalyze?

A

dioxygenation of arachidonic acid or EPA/ synthesis of lipoxins and leukotrienes

17
Q

What are the functions of leukotrienes?

A

proinflammatory mediators, chemotactic, elicit bronchoconstriction

18
Q

What are the functions of lipoxins?

A

counter-regulatory to leukotrienes