Eicosanoids Flashcards

1
Q

Three major classes of eicosanoids:

A
  1. Prostaglandins (PGs)
  2. Thromboxanes (TXs)
  3. Leukotrienes (LTs)
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2
Q

…… cleaves PIP2 to generate arachidonic acid and Lyso-PIP2

A

Phospholipase A2

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3
Q

Functions of Eicosanoids:

A

• Produce a wide range of biological effects of the inflammatory response
– Intensity and duration of pain and fever
– Reproductive function (including the induction of labor)

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4
Q

The following are characteristic of …….
– Inhibiting gastric acid secretion
– Regulating blood pressure through vasodilation or constriction
– Inhibiting, or, activating platelet aggregation and hence regulation of thrombosis

A

Eicosanoids

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5
Q

What inhibits the synthesis of arachidonic acid?

A

Corticosteriods

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6
Q

What inhibits Cycloxygenase 1 and 2 (COX 1)?

A

Aspirin and Other NSAIDS

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7
Q

Eicosanoids function by using specific receptor-mediated G-protein linked signaling pathways that result in the …………

A

Increase in either c-AMP levels or an increase in intracellular calcium

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8
Q

If present in a phospholipid, arachidonic acid will be at the …… position

A

C-2 position

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9
Q

Phospholipase A2 acts on phosphatidyl-inositol and releases …….

A

Arachidonic Acid

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10
Q

The immediate dietary precursor of arachidonate is ………..

A

Linoleic Acid

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11
Q

What is the result of inhibiting both COX 1 and Cox 2?

A

Reduced production of both prostaglandins and thromboxanes

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12
Q

Prostacyclin (PGI2) produced by …………… and Thromboxane A2 (TXA2), produced by ……………., play opposing key roles in regulating platelet aggregation and vasodilation

A

Endothelial Cells

Platelets

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13
Q
The following functions are characteristic of.........
Platelet Aggregation
Vasoconstriction
Mobilizes intracellular calcium
Contraction of smooth muscle
A

Thromboxane A2 (TXA2)

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14
Q

The following functions are characteristic of………
Vasodilation
Inhibits platelet Aggregation

A

Prostacyclin (PGI2)

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15
Q

How does aspirin inhibit COX1 and COX2?

A

Aspirin inhibits COX-1 and COX-2 irreversibly by acetylation of a serine amino acid side chain in the active site of these enzymes

The result is to decrease synthesis of eicosanoids

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16
Q

Aspirin’s inhibition of COX1 and COX2 results in……

A

-A decrease in platelets aggregation due to the reduced synthesis of TXA2 by platelets

17
Q

Two different types of PUFA’s:

A

2- Series (linoleic acid)

3-Series (linolenic acid)

18
Q

2-Series (linoleic acid) is derived from…… and produces ……

A

Arachidonic Acid

PGI2 and TXA2

19
Q

3-Series (linolenic acid) is derived from…… and produces ……

A

Eicosapentaenoic Acid

PGI3 and TXA3

20
Q

Either ……….. or ………….can be released by activation of PLA2 and used for eicosanoid synthesis.

A

EPA or arachidonic acid

21
Q

TXA3 (from EPA) is ………… potent than TXA2 (from arachidonic acid) in platelet aggregation

22
Q

Arachidonic Acid is converted to 5-Hyroperoxyeicosatetrainoic acid (HPETE) by …………
5-HPETE is then converted into Leukotriene A4 (LTA4)

A

5-Lipoxygenase

23
Q

LTC, LTD, LTE and LTF contain either a peptide or cysteine in their structure and are therefore called

A

Cysteinyl-leukotrienes

24
Q

The ……………..are released during anaphylaxis and they are components of the slow-reacting substance of anaphylaxis (SRS-A). They are much more potent than histamine.

A

Cysteinyl-leukotrienes

25
The following are characteristic of ...... • Airflow obstruction • Increased secretion of mucus • Bronchoconstriction • Infiltration of inflammatory cells in the airway wall
Asthma
26
Asthma treatment can include ........of leukotriene synthesis or receptors.
Inhibition
27
How do drugs inhibit leukotriene action?
1) Inhibit the release of arachidonic acid (cortisol), this also leads to less PG and TX synthesis 2) Inhibit of 5-lipoxygenase activity (results in reduced leukotriene synthesis) 3) Act as Cysteinyl-leukotriene receptor antagonists
28
Prostaglandin E2 (PGE2) is mainly synthesized in the.....
Most Tissues, especially kidney
29
Functions of Prostaglandin E2:
Mediator of inflammation; Vasodilation; Relaxes smooth muscle; Used to induce labor