Questions and Answers
What is the primary physiological role of prostaglandins in the body?
Which pathway is NOT involved in the synthesis of eicosanoids?
What is the structure characteristic of thromboxanes?
How are eicosanoids produced within the body?
Signup and view all the answers
Which cellular response is specifically attributed to the action of leukotrienes?
Signup and view all the answers
What function do eicosanoids NOT have in the body?
Signup and view all the answers
Which of the following best describes the relationship between eicosanoids and G-protein coupled receptors?
Signup and view all the answers
Which of the following is a primary function of thromboxanes?
Signup and view all the answers
What property of eicosanoids allows them to have diverse tissue functions?
Signup and view all the answers
What is the primary effect of thromboxane A2 in relation to platelet function?
Signup and view all the answers
Which of the following statements regarding prostacyclin (PGI2) is correct?
Signup and view all the answers
What is the mechanism of action of low-dose aspirin therapy?
Signup and view all the answers
How does the inhibition of COX-1 by NSAIDs affect platelet function?
Signup and view all the answers
What is the significance of platelet renewal in relation to aspirin treatment?
Signup and view all the answers
What role does cortisol play in platelet homeostasis?
Signup and view all the answers
What is the primary function of COX-1 in the body?
Signup and view all the answers
What type of inhibitor is celecoxib categorized as?
Signup and view all the answers
Which fatty acid serves as a dietary precursor for the synthesis of prostaglandins?
Signup and view all the answers
How does ibuprofen primarily act on PGH synthase?
Signup and view all the answers
What is the primary role of 5-lipoxygenase in the lipoxygenase pathway?
Signup and view all the answers
Why does acetaminophen have poor ability to inhibit COX in high concentrations of peroxides?
Signup and view all the answers
What pathway does the lipoxygenase family affect primarily?
Signup and view all the answers
What influences the activity of COX-2 in tissues?
Signup and view all the answers
Which of the following statements best describes leukotrienes?
Signup and view all the answers
What determines the rate of product formation from arachidonic acid?
Signup and view all the answers
Which enzyme is responsible for hydrolyzing arachidonate?
Signup and view all the answers
How is arachidonic acid stored in cell membranes?
Signup and view all the answers
What is a primary precursor to thromboxanes and prostaglandins?
Signup and view all the answers
Which of the following stimulates arachidonic acid release in specific cell types?
Signup and view all the answers
What is the role of phospholipase C regarding phosphatidylinositol?
Signup and view all the answers
Which type of cell would bradykinin specifically stimulate for arachidonic acid release?
Signup and view all the answers
Which of the following is NOT a product derived from arachidonic acid metabolism?
Signup and view all the answers
Which phospholipase is primarily involved in the release of arachidonic acid?
Signup and view all the answers
What role does thrombin play regarding arachidonic acid?
Signup and view all the answers
What is indicated by a subscript in nomenclature?
Signup and view all the answers
Which of the following NSAIDs is specifically associated with increased leukotriene levels?
Signup and view all the answers
How does the structure of Hydroperoxy-eicosatetraenoic acid differ from other eicosanoids?
Signup and view all the answers
What effect do NSAIDs such as aspirin have on the blood flow at a clot site?
Signup and view all the answers
Substitutions at which positions are indicated for Hydroperoxy in nomenclature?
Signup and view all the answers
Which of the following is NOT a recognized nonsteroidal anti-inflammatory drug (NSAID)?
Signup and view all the answers
What is the primary biological activity associated with Hydroperoxy-eicosatetraenoic acid?
Signup and view all the answers
Which NSAID is known for potentially triggering asthma attacks?
Signup and view all the answers
What is a common use of eicosanoids in the body?
Signup and view all the answers
What does the additional capital letter signify in the nomenclature of compounds?
Signup and view all the answers
Study Notes
Eicosanoids Function
- Derived from arachidonic acid, a 20-carbon polyunsaturated fatty acid.
- Not stored but synthesized on demand, responding to cellular signaling.
- Mediated by G-protein coupled receptors, influencing various physiological functions.
Functions of Eicosanoids
- Reproductive functions including smooth muscle contraction during menstruation and labor.
- Modulation of inflammation, resulting in fever and pain responses.
- Involvement in blood clot formation and regulation of blood flow to specific organs.
- Influence on wake-sleep cycles and responsiveness to hormones like epinephrine and glucagon.
- Regulation of gastric acid secretion and blood pressure.
Pathways for Eicosanoid Synthesis
- Cyclooxygenase Pathway: Produces prostaglandins and thromboxanes.
- Lipoxygenase Pathway: Generates leukotrienes, HETE (Hydroxyeicosatetraenoic acid), and lipoxins.
- Cytochrome P450 System: Synthesizes epoxides, HETE, and diHETE.
Prostaglandins
- Composed of a 20-carbon fatty acid structure with a 5-membered internal carbon ring and a hydroxyl group at carbon 15.
- Nomenclature begins with "PG" followed by capital letters indicating specific substitutions.
Thromboxanes
- Feature a 6-membered ring including an oxygen atom.
- Nomenclature uses "TX" with capital letters for ring substitutions and subscripts indicating unsaturated bonds.
- Function primarily in blood clot formation and reduction of blood flow to injury sites.
Hydroperoxy-eicosatetraenoic Acid (HETE)
- Hydroxyl fatty acid derivative of arachidonic acid, lacking a ring structure.
- Nomenclature includes hydroperoxy substitutions at positions 5, 12, and 15.
Metabolism of Eicosanoids
- Arachidonic acid is a precursor for major eicosanoids, stored as phospholipid esters in cell membranes.
- Released by phospholipase A2 when stimulated, influencing the rate of eicosanoid synthesis.
- Specific agonists like thrombin and bradykinin stimulate arachidonic acid production.
Synthesis of Eicosanoids
- Linoleic acid, an omega-6 fatty acid, is essential for prostaglandin production.
- Arachidonic acid is derived from dietary intake of linoleic acid.
- Prostaglandin H2 (PGH2) synthesized through oxidative cyclization of arachidonic acid, requiring oxygen and reducing agents.
Inhibition of Eicosanoid Synthesis
- Nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin, ibuprofen inhibit cyclooxygenase (COX) enzymes, shifting production to lipoxygenase pathways.
- NSAIDs can potentially induce asthma attacks through increased leukotriene synthesis.
Roles of Prostaglandins in Platelet Homeostasis
- Thromboxane A2 (TXA2): Promotes platelet aggregation and vasoconstriction; synthesized by COX-1 in activated platelets.
- Prostacyclin (PGI2): Inhibits platelet aggregation and promotes vasodilation; produced by COX-2 in vascular endothelium.
Aspirin and Its Effects
- Provides antithrombogenic effects by irreversibly acetylating COX enzymes, reducing TXA2 synthesis in platelets while affecting PGI2 synthesis in endothelial cells.
- Low-dose aspirin therapy lowers the risk of stroke and heart attacks by decreasing thrombus formation.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz focuses on the functions of arachidonic acid, a polyunsaturated fatty acid derived from 20-carbon chains. We explore its production, action at low concentrations, and its role in smooth muscle contraction during menstruation and labor. Test your knowledge on cellular and tissue functions mediated by G-protein coupled receptors.