B59: Eicosanoids
SGU Biochemistry - Fall 2009, Lecture 59: EicosanoidsReview questions from Lippincott, Mark's, BRS, and lecture notes from Dr. Trotz
Questions and Answers
- 1.
Prostaglandins, and the related compounds thromboxanes and ____, are collectively known as eicosanoids (L p. 213).
Explanation
Prostaglandins, thromboxanes, and leukotrienes are all types of eicosanoids. Eicosanoids are signaling molecules that are derived from fatty acids and play important roles in inflammation, immune response, and various other physiological processes. Prostaglandins and thromboxanes are involved in regulating inflammation and blood clotting, while leukotrienes are primarily associated with allergic and inflammatory responses. Therefore, leukotrienes are the correct answer to complete the list of eicosanoids.Rate this question:
- 2.
Eicosanoids differ from the true hormones in that they are produced in very ____ amounts in almost all tissues rather than in specialized glands (L p. 213).
- A.
Large
- B.
Small
Correct Answer
B. SmallExplanation
Eicosanoids differ from true hormones because they are produced in very small amounts in almost all tissues, rather than in specialized glands. This means that eicosanoids have a more widespread and localized effect in the body, compared to hormones which are typically produced in larger amounts by specific glands and have a more systemic effect.Rate this question:
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- 3.
Eicosanoids act ____ rather than after transport in the blood to ____ sites, as occurs with true hormones such as insulin (L p. 213).
- A.
Locally, distant
- B.
Distally, local
Correct Answer
A. Locally, distantExplanation
Eicosanoids act locally rather than after transport in the blood to distant sites. This means that they are produced and exert their effects in the immediate vicinity of their site of production, instead of being transported through the bloodstream to act on distant target cells or tissues. This is in contrast to true hormones like insulin, which are produced in one location and then transported through the blood to act on target cells in various parts of the body.Rate this question:
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- 4.
Eicosanoids are not stored, and they have an extremely ____ half-life (L p. 213).
- A.
Long
- B.
Short
Correct Answer
B. ShortExplanation
Eicosanoids are not stored, meaning they are synthesized and released on demand. They have a short half-life, which means they are rapidly metabolized and cleared from the body. This short half-life allows for precise control and regulation of their effects on various physiological processes.Rate this question:
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- 5.
Free ____ ____ yields PGH2 (L p. 213).
Correct Answer
arachidonic acidExplanation
Arachidonic acid is a type of fatty acid that is found in the body and is involved in the production of various substances, including prostaglandins. Prostaglandin H2 (PGH2) is a precursor molecule that is derived from arachidonic acid. Therefore, the correct answer is arachidonic acid because it is the compound that yields PGH2.Rate this question:
- 6.
PGH synthase, or prostaglandin endoperoxide synthase, has two catalytic activities: fatty acid cyclooxygenase and _____ (L p. 213 and Trotz Lectures 53-59 p.61).
Correct Answer
peroxidaseExplanation
PGH synthase, also known as prostaglandin endoperoxide synthase, possesses two catalytic activities: fatty acid cyclooxygenase and peroxidase. The given answer, peroxidase, is the missing catalytic activity of PGH synthase. This enzyme is responsible for the conversion of fatty acids into prostaglandin endoperoxides and also plays a role in the production of other bioactive molecules. The information regarding the two catalytic activities of PGH synthase can be found on page 213 of the mentioned source and in the Trotz Lectures on pages 53-59, specifically on page 61.Rate this question:
- 7.
COX-1 is _____, while COX-2 is ______ (L p. 213 and Trotz Lectures 53-59 p.63).
- A.
Inducible, constitutive
- B.
Constitutive, inducible
Correct Answer
B. Constitutive, inducibleExplanation
COX-1 is constitutive, meaning it is constantly present and active in the body. On the other hand, COX-2 is inducible, which means it is only produced in response to certain stimuli or conditions. This difference in their regulation and expression levels is important in understanding their roles and functions in various physiological processes.Rate this question:
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- 8.
Asthma treatment can include inhibition of ____ synthesis or inhibition of _____ receptors (same word) (L p. 214 and Trotz Lectures 53-59 p.67).
Correct Answer
leukotrieneExplanation
Asthma treatment can involve inhibiting the synthesis of leukotrienes or blocking leukotriene receptors. Leukotrienes are inflammatory molecules that play a role in the pathogenesis of asthma. By inhibiting their synthesis or blocking their receptors, the inflammatory response in the airways can be reduced, leading to improved asthma control. This approach is commonly used in the management of asthma and can be effective in reducing symptoms and preventing exacerbations.Rate this question:
- 9.
Eicosanoids are highly active physiological compounds that are synthesized upon demand from a fatty acid with ___ carbons (L p. 213 and Trotz Lectures 53-59 p.58).
Correct Answer
20, twentyExplanation
Eicosanoids are synthesized from a fatty acid with 20 carbons. This information can be found on page 213 of the textbook and in the Trotz Lectures on pages 53-59, specifically on page 58.Rate this question:
- 10.
_____ and thromboxanes are involved in many physiological actions, often counteracting each other. They are needed to uphold normal cell functions. Trotz Lectures 53-59 p.58
Correct Answer
prostaglandinsExplanation
Prostaglandins and thromboxanes are molecules that play important roles in various physiological processes. They often have opposing actions, meaning they counteract each other's effects. Both prostaglandins and thromboxanes are necessary for maintaining normal cell functions in the body. This information is mentioned in Trotz Lectures 53-59 on page 58.Rate this question:
- 11.
____ mainly act as inflammatory mediators together with lipoxins and HETE. Trotz Lectures 53-59 p.58
Correct Answer
leukotrienesExplanation
Leukotrienes are known to primarily function as inflammatory mediators, along with lipoxins and HETE. This information is mentioned in the Trotz Lectures, specifically on page 58, between lecture numbers 53-59. Therefore, the correct answer for this question is leukotrienes.Rate this question:
- 12.
The release of arachidonic acid provides the substrate for the synthesis of eicosanoids. This release can involve phospholipase A2, which is inhibited by _____. Trotz Lectures 53-59 p.59
Correct Answer
corticosteroids, cortisolExplanation
Corticosteroids, such as cortisol, inhibit phospholipase A2, which is involved in the release of arachidonic acid. This inhibition prevents the synthesis of eicosanoids, as arachidonic acid is the substrate required for their production. Therefore, corticosteroids indirectly inhibit the synthesis of eicosanoids by inhibiting the enzyme responsible for releasing the necessary substrate.Rate this question:
- 13.
5-HPETE is an intermediate of _____ synthesis. Trotz Lectures 53-59 p.58
Correct Answer
leukotrieneExplanation
5-HPETE is an intermediate of leukotriene synthesis. Leukotrienes are a group of inflammatory molecules that are involved in various physiological processes, including asthma and allergic reactions. 5-HPETE is formed from the metabolism of arachidonic acid and serves as a precursor for the synthesis of leukotrienes. Therefore, it can be concluded that 5-HPETE is an intermediate in the synthesis of leukotrienes.Rate this question:
- 14.
LTC4, LTD4, and ____ are inflammatory mediators that are components of SRS-A and lead to severe bronchoconstriction and lung edema. Trotz Lectures 53-59 p.59
Correct Answer
LTE4, lte4Explanation
LTE4 is an inflammatory mediator that is a component of SRS-A (slow-reacting substance of anaphylaxis). It, along with LTC4 and LTD4, leads to severe bronchoconstriction and lung edema. LTE4 is formed from the metabolism of LTD4 and plays a crucial role in the pathophysiology of asthma and other allergic respiratory diseases. Its presence contributes to the narrowing of airways and the accumulation of fluid in the lungs, resulting in the symptoms associated with severe bronchoconstriction and lung edema.Rate this question:
- 15.
PGH2 is an intermediate of prostaglandin and ____ synthesis. Trotz Lectures 53-59 p.59
Correct Answer
tx, thromboxane, TXExplanation
PGH2 is an intermediate of prostaglandin and thromboxane synthesis.Rate this question:
- 16.
___ and TXA2 have opposing effects. Trotz Lectures 53-59 p.59
Correct Answer
pgi2, PGI2, prostacyclinExplanation
PGI2, also known as prostacyclin, and TXA2 have opposing effects. Prostacyclin is a vasodilator and inhibitor of platelet aggregation, while TXA2 is a vasoconstrictor and promoter of platelet aggregation. These two substances play important roles in regulating blood flow and clotting.Rate this question:
- 17.
____ and PGF2-alpha have partially opposing effects. Trotz Lectures 53-59 p.59
Correct Answer
PGE2, pge2Explanation
PGE2 and PGF2-alpha have partially opposing effects. This means that they have different effects on certain processes or functions in the body. While the specific effects are not mentioned in the given information, it can be inferred that PGE2 and pge2 are the substances being referred to as they are mentioned in the same context.Rate this question:
- 18.
The ___ pathway includes fatty acid cyclooxygenase and leads to prostaglandins or thromboxane. Trotz Lectures 53-59 p.60
- A.
Cyclic
- B.
Linear
Correct Answer
A. CyclicExplanation
The correct answer is "cyclic" because the pathway mentioned in the question involves fatty acid cyclooxygenase, which is an enzyme that catalyzes the conversion of arachidonic acid into cyclic endoperoxides. These cyclic endoperoxides can then be further metabolized to produce prostaglandins or thromboxane. Therefore, the pathway is cyclic in nature.Rate this question:
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- 19.
The ___ pathway includes lipoxygenases and leads to leukotrienes, HETE, and lipoxins. Trotz Lectures 53-59 p.60
- A.
Cyclic
- B.
Linear
Correct Answer
B. LinearExplanation
The correct answer is "linear" because the passage states that the pathway includes lipoxygenases, which are enzymes that catalyze the oxygenation of polyunsaturated fatty acids in a linear manner. This linear pathway leads to the production of leukotrienes, HETE, and lipoxins.Rate this question:
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- 20.
Aspirin is an ___ inhibitor of COX. Trotz Lectures 53-59 p.61
- A.
Reversible
- B.
Irreversible
Correct Answer
B. IrreversibleExplanation
Aspirin is known to irreversibly inhibit the enzyme COX (cyclooxygenase). This means that once aspirin binds to the active site of COX, it forms a covalent bond with the enzyme, permanently inactivating it. This irreversible inhibition is a key characteristic of aspirin's mechanism of action and is responsible for its long-lasting effects on platelet aggregation and inflammation.Rate this question:
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- 21.
Thromboxane leads to platelet _____, while prostacyclin leads to platelet _____. Trotz Lectures 53-59 p.61
- A.
Aggregation, inhibition
- B.
Inhibition, aggregation
Correct Answer
A. Aggregation, inhibitionExplanation
Thromboxane is a hormone that promotes platelet aggregation, which means it causes the platelets to clump together and form blood clots. On the other hand, prostacyclin inhibits platelet aggregation, meaning it prevents the platelets from sticking together and forming clots.Rate this question:
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- 22.
Inhibition of COX by aspirin is done by acetylation of a ____ residue in the active site. Trotz Lectures 53-59 p.63
Correct Answer
serineExplanation
Aspirin inhibits COX by acetylating a serine residue in the active site. This acetylation prevents the enzyme from functioning properly, thereby reducing the production of prostaglandins and other inflammatory compounds. By targeting this specific residue, aspirin effectively reduces pain, inflammation, and fever.Rate this question:
- 23.
____ is involved with normal physiological functions of PG and TX, like gastric protection and limiting acid secretion, maintenance of renal blood flow, vascular homostasis and hemostasis.
- A.
COX-1
- B.
COX-2
Correct Answer
A. COX-1Explanation
COX-1 is involved in normal physiological functions of prostaglandins (PG) and thromboxanes (TX), which include gastric protection and limiting acid secretion, maintenance of renal blood flow, vascular homeostasis, and hemostasis. COX-1 is constitutively expressed in various tissues and is responsible for the production of PGs and TXs that play a role in these physiological processes. COX-2, on the other hand, is primarily induced during inflammation and is responsible for the production of PGs that mediate pain, fever, and inflammation.Rate this question:
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- 24.
Continuous severe inhibition of ____ at high aspirin doses can lead to stomach ulcers and kidney damage. Trotz Lectures 53-59 p.63
Correct Answer
COX-1
cox1
cox-1Explanation
Continuous severe inhibition of COX-1 at high aspirin doses can lead to stomach ulcers and kidney damage. COX-1 is an enzyme involved in the production of prostaglandins, which are important for maintaining the integrity of the stomach lining and regulating kidney function. Inhibition of COX-1 reduces the production of these protective prostaglandins, leading to increased risk of stomach ulcers and kidney damage.Rate this question:
- 25.
_____, in general, can induce labor. Trotz Lectures 53-59 p.64
Correct Answer
prostaglandinsExplanation
Prostaglandins, in general, can induce labor. This information is mentioned in the Trotz Lectures on pages 53-59, specifically on page 64. Prostaglandins are a group of hormones that play a role in various physiological processes, including labor and childbirth. They can help to ripen the cervix, stimulate contractions, and initiate the labor process. Therefore, prostaglandins can be used as a medical intervention to induce labor when necessary.Rate this question:
- 26.
____ can lead to vasodilation, relaxation of smooth muscle (cAMP). Trotz Lectures 53-59 p.64
- A.
PGE2
- B.
PGF2-alpha
- C.
PGI2
- D.
TXA2
Correct Answer
A. PGE2Explanation
PGE2 can lead to vasodilation and relaxation of smooth muscle through the activation of cAMP. This is supported by the information given in Trotz Lectures 53-59 on page 64.Rate this question:
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- 27.
____ is produced by vascular endothelial cells, inhibits platelet aggregation, and vasodilates. Trotz Lectures 53-59 p.64
- A.
PGE2
- B.
PGF2-alpha
- C.
PGI2
- D.
TXA2
Correct Answer
C. PGI2Explanation
PGI2, also known as prostacyclin, is produced by vascular endothelial cells. It inhibits platelet aggregation, meaning it prevents platelets from clumping together and forming blood clots. Additionally, PGI2 has vasodilatory effects, meaning it relaxes and widens blood vessels, leading to increased blood flow.Rate this question:
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- 28.
____ is mainly produced by platelets, stimulates platelet aggregation, vasoconstricts, and bronchoconstricts. Trotz Lectures 53-59 p.64
- A.
PGE2
- B.
PGF2-alpha
- C.
PGI2
- D.
TXA2
Correct Answer
D. TXA2Explanation
TXA2, also known as thromboxane A2, is mainly produced by platelets and has several effects on the body. It stimulates platelet aggregation, which is the process of platelets clumping together to form a blood clot. TXA2 also causes vasoconstriction, which narrows the blood vessels and increases blood pressure. Additionally, it causes bronchoconstriction, which leads to the narrowing of the airways in the lungs. These effects of TXA2 play important roles in hemostasis, the regulation of blood flow, and the inflammatory response.Rate this question:
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- 29.
____ is a vasoconstrictor, contracts smooth muscle, and bronchoconstricts. Trotz Lectures 53-59 p.64
- A.
PGE2
- B.
PGF2-alpha
- C.
PGI2
- D.
TXA2
Correct Answer
B. PGF2-alpHaExplanation
PGF2-alpha is a prostaglandin that acts as a vasoconstrictor, causing the constriction of blood vessels. It also contracts smooth muscle, which can lead to various effects in different organs and tissues. Additionally, PGF2-alpha is known to induce bronchoconstriction, causing the narrowing of the airways in the lungs. These actions make PGF2-alpha a potent regulator of vascular tone, smooth muscle contraction, and bronchial constriction.Rate this question:
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- 30.
Prostaglandins have a ___-membered ring, while thromxane has a ___-membered ring.
- A.
4, 5
- B.
5, 4
- C.
5, 6
- D.
6, 5
- E.
5, 7
Correct Answer
C. 5, 6Explanation
Prostaglandins have a 5-membered ring, while thromboxane has a 6-membered ring.Rate this question:
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- 31.
EPA instead of ___ ____ can be released and used for eicosanoid synthesis. Trotz Lectures 53-59 p.64
Correct Answer
arachidonic acidExplanation
The correct answer is "arachidonic acid" because according to the information provided in the Trotz Lectures, EPA (eicosapentaenoic acid) can be released and used for eicosanoid synthesis. This implies that EPA is an alternative to arachidonic acid in the process of eicosanoid synthesis.Rate this question:
- 32.
LTA is an intermediate that is changed to ____ in neutrophils and monocytes. Trotz Lectures 53-59 p.66
Correct Answer
LTB
ltbExplanation
LTA (lipoteichoic acid) is an intermediate molecule that undergoes a change to LTB (lipoteichoic acid binding protein) in neutrophils and monocytes. This change is likely a part of the immune response, as LTB is involved in the binding and activation of immune cells.Rate this question:
- 33.
___ increases vascular permeability and acts as chemo-attractant for neutrophils. Trotz Lectures 53-59 p.66
- A.
LTA
- B.
LTB
- C.
LTC
- D.
LTD
- E.
LTE
Correct Answer
B. LTBExplanation
LTB (Lipoteichoic acid) increases vascular permeability and acts as a chemo-attractant for neutrophils. This information is stated in Trotz Lectures 53-59 on page 66.Rate this question:
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- 34.
____ is used in mast cells and eosinophils to form LTC by addition of the tripeptide GSH. Trotz Lectures 53-59 p.66
- A.
LTA
- B.
LTB
- C.
LTC
- D.
LTD
- E.
LTE
Correct Answer
A. LTAExplanation
LTA is used in mast cells and eosinophils to form LTC by addition of the tripeptide GSH.Rate this question:
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- 35.
____ increase vascular permeability but lead also to severe bronchoconstriction. Trotz Lectures 53-59 p.66
- A.
LTA, LTB, LTC
- B.
LTB, LTC, LTD
- C.
LTC, LTD, LTE
Correct Answer
C. LTC, LTD, LTEExplanation
LTs (leukotrienes) are lipid mediators that are produced by various cells, including mast cells and leukocytes, during an inflammatory response. They are known to increase vascular permeability, which allows immune cells to enter the site of inflammation. Additionally, LTs can also cause severe bronchoconstriction, leading to symptoms such as wheezing and difficulty breathing. Therefore, the correct answer is LTC, LTD, LTE, as these leukotrienes both increase vascular permeability and cause bronchoconstriction.Rate this question:
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- 36.
The cysteinyl-leukotrienes are components of the slow-reacting substance of _____ (SRS-A). Trotz Lectures 53-59 p.66
Correct Answer
anaphylaxis
anaphlaxisExplanation
The cysteinyl-leukotrienes are known to be components of the slow-reacting substance of anaphylaxis (SRS-A). They are involved in the immune response and inflammation that occurs during anaphylaxis, a severe allergic reaction.Rate this question:
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